Geological Storage of Carbon Dioxide

Transcription

1 RECOMMENDED PRACTICE DNV-RP-J203 Geological Storage of Carbon Dioxide APRIL 2012 This document has been amended since the main revision (April 2012), most recently in July See Changes on page 3. The electronic pdf version of this document found through is the officially binding version

2 FOREWORD DNV is a global provider of knowledge for managing risk. Today, safe and responsible business conduct is both a license to operate and a competitive advantage. Our core competence is to identify, assess, and advise on risk management. From our leading position in certification, classification, verification, and training, we develop and apply standards and best practices. This helps our customers safely and responsibly improve their business performance. DNV is an independent organisation with dedicated risk professionals in more than 100 countries, with the purpose of safeguarding life, property and the environment. DNV service documents consist of among others the following types of documents: Service Specifications. Procedural requirements. Standards. Technical requirements. Recommended Practices. Guidance. The Standards and Recommended Practices are offered within the following areas: A) Qualification, Quality and Safety Methodology B) Materials Technology C) Structures D) Systems E) Special Facilities F) Pipelines and Risers G) Asset Operation H) Marine Operations J) Cleaner Energy O) Subsea Systems U) Unconventional Oil & Gas Det Norske Veritas AS April 2012 Any comments may be sent by to rules@dnv.com This service document has been prepared based on available knowledge, technology and/or information at the time of issuance of this document, and is believed to reflect the best of contemporary technology. The use of this document by others than DNV is at the user's sole risk. DNV does not accept any liability or responsibility for loss or damages resulting from any use of this document.

3 Changes Page 3 CHANGES CURRENT General This is a new document. Amendment July 2013 An editorial correction has been made in the first row of Table 5-1.

4 Contents Page 4 CONTENTS CHANGES CURRENT Preface Introduction General Objective Approach Scope Users Relationship to other codes Structure of this document Definitions and abbreviations Definitions Abbreviations Verbal Forms Storage Site Screening and Appraisal Introduction Screening Appraisal Permitting Introduction Permit context and requirements (Step 1, Figure 5-1) Risk performance targets (Step 2, Figure 5-1) Storage Permit application (Step 3, Figure 5-1) Closure Permit application (alternative Step 3, Figure 5-1) Evaluate completeness (Step 4, Figure 5-1) Submit application (Step 5, Figure 5-1) Risk management Introduction Risk management context Risk Assessment Risk treatment Risk management review and documentation Well qualification Introduction Set requirements in qualification basis Risk assessment for well qualification Plan well qualification & select qualification activities Evaluate likelihood of success Evaluate need for modifications Update qualification basis Initial Well Qualification Report Execute well qualification activities Performance Assessment Requirements met? Final Well Qualification Report...48 Appendix A. Subsurface Data Appendix B. Generic failure modes for well integrity under exposure to Carbon Dioxide... 54

5 Sec.1 Preface Page 5 1 Preface The main objective of this Recommended Practice (RP) is to provide a systematic approach to the selection, qualification and management of geological storage sites for carbon dioxide (CO 2 ). This RP specifies what, in DNV s opinion, is the best industry practice for that purpose. This RP may be used as a basis for verification and is considered applicable worldwide. 2 Introduction 2.1 General There is growing consensus that global warming and climate change are the anthropogenic results of greenhouse gas emissions from the combustion of fossil fuels, such as natural gas, oil and coal. The world's population is steadily growing, as are its energy needs. It is expected that a significant part of the world's future need for electrical energy and heat will come from burning of fossil fuels, implying increased CO 2 emissions to the atmosphere. Carbon Capture and Storage (CCS) offers an opportunity to mitigate global warming and associated negative impacts by capturing and storing CO 2 that would otherwise be emitted to the atmosphere. CCS refers to the process of capturing CO 2 from large point sources, such as fossil fuel power plants, cement factories, oil refineries, or iron and steel mills, and injecting and isolating the captured CO 2 in deep geological formations. For CCS to be effective the geological formations into which CO 2 is injected must be carefully selected and qualified to ensure that they can provide long-term containment of injected CO 2 streams. 2.2 Objective This RP provides users with systematic procedures and performance requirements for assessing and verifying the suitability of storage sites and projects for environmentally safe, long-term geological storage of injected CO 2 streams. This includes assessment and verification of monitoring and risk management plans tailored to the characteristics of each storage site. 2.3 Approach This RP applies the principles of Technology Qualification given in DNV-RP-A203 to managing the technical risks related to CO 2 geological storage. Technology Qualification is a methodology developed by DNV for reducing the risk and uncertainty associated with implementation of new technology. The following principles shall control the qualification process: specifications and performance requirements shall be clearly defined, quantified and documented a qualification plan shall be developed to evaluate fulfilment of the specified requirements threats to the performance requirements shall be identified tailored threat identification should be carried out for novel elements where the uncertainty is most significant the relevance of individual threats shall be determined based on their risk risk assessments shall be executed and documented in a transparent and traceable way risk assessments shall be used to evaluate the appropriateness of requirements and to guide decision making the qualification process and the evaluation of fulfilment of performance requirements shall be documented. 2.4 Scope General This RP defines performance requirements and procedures for the following: the selection and qualification of geological storage sites for long-term storage of CO 2 the documentation of storage site characterization and storage site development plans as a basis for permit applications/reviews risk management throughout life cycle of CO 2 geological storage projects, from initial screening and storage site selection through to storage site closure and preparation for post-closure stewardship monitoring and storage performance verification well assessment and management planning storage site closure and preparation for post-closure stewardship. Where the term CO 2 is used in the guideline, it assumes that carbon dioxide is pressurized; may or may not contain water; exists either as a liquid, super critical fluid or a gas; and also includes carbon dioxide dissolved in water contained in the injection zone.

6 Sec.2 Introduction Page Qualification requirements The following qualification requirements are summarized in tables throughout the document: Table 4-1: Requirements to potential storage sites that should be included in the Screening Basis. Table 4-3: Requirements to prospective storage sites that shall be included in the Appraisal Basis (in addition those listed in Table 4-1). Table 5-2: Requirements for storage site closure. Table 5-3: Requirements for the Storage Development Plan. Table 5-1: Requirements for the Monitoring Plan Exclusions This RP does not include performance requirements or recommended procedures for: the selection and qualification of hydrocarbon fields for enhanced recovery by CO 2 injection the capture of CO 2 and its transportation from source to storage site management of surface facilities and well operations (injection wells, production wells, monitoring wells) accounting of CO 2 emissions avoided CO 2 injection and storage in un-mineable coal beds, basalt formations, shales, and salt caverns underground storage in materials involving the use of any form of engineered containers Application This RP may be applied as a basis for verification and risk-based decision making, including but not limited to: guidance and quality assurance of storage site planning and development demonstration of compliance with industry best practice implementation of regulations independent assessment and verification stakeholder communication. The requirements in this RP shall be subordinate to local regulations. 2.5 Users Users of this RP may typically be: an operator a regulator an independent verifier an investor or other financial stakeholder. 2.6 Relationship to other codes Generic qualification procedures for new technology are given in DNV-RP-A203. While these procedures cover a generic approach, the present document describes how these principles shall be applied to qualify and manage CO 2 geological storage sites. Only the storage component of the CCS value chain from the injection zone up to and including the CO 2 injection well heads is addressed in this RP. Elements of the capture and (pipeline) transport components of the CCS chain are given in DNV-RP-J201 and DNV-RP-J202, respectively. This RP incorporates and combines the guidance given in the following two documents: CO2QUALSTORE Guideline for Selection and Qualification of Sites and Projects for CO 2 Geological Storage of CO 2 (2010). CO2WELLS Guideline for the Risk Management of Existing Wells at CO 2 Geological Storage Sites (2011). These two guidelines were the final deliverables from joint industry projects whereas this RP has been developed, and will be maintained, by DNV.

7 Sec.2 Introduction Page Structure of this document Initiate Project Select Prospective Sites Select Storage Site Storage Permit application Initiate Construction Initiate CO 2 Injection Qualify for Site Closure Decommision Screening EP Appraisal Permitting SP Design Construct Operate Close TOR Risk Management Screening & Appraisal Permitting Permitting Well Qualification EP Exploration Permit SP CO 2 Storage Permit TOR Transfer of Responsibility Figure 2-1 Life cycle diagram for a CO 2 geological storage project showing decision gates (diamonds) and permits (stars). The sections within this RP are shown underneath the relevant life cycle stages as grey bars. This document is structured around the generic decision gate model for a CO 2 storage site, as shown in Fig.2-1. The decision gate model covers the life cycle of a CO 2 geological storage project. Decision gates 2, 4 and 8 are designed to precede an operator s application for an exploration permit, storage permit and transfer of responsibility permit, or their equivalents. This RP contains the following sections: Section 4: Storage Site Screening and Appraisal Section 5: Permitting Section 6: Risk Management Section 7: Well Qualification.

8 Sec.3 Definitions and abbreviations Page 8 3 Definitions and abbreviations 3.1 Definitions Term Definition Accounting and Reporting One component of a Storage Development Plan. It is a document that describes how an Plan operator shall account for and report avoided emissions of CO 2 for regulators and/or emissions trading schemes. The content and structure of the Accounting and Reporting plan is not described in this document because this is expected to be prescribed by regulations and/ or requirements of an emissions trading scheme. Acid gas Natural gas or gas mixture which contains significant amounts of hydrogen sulfide (H 2 S) and/or CO 2. Appraisal Communication A plan that describes how the operator intends to communicate with the relevant stakeholders Plan that influenced the requirements in the Appraisal Basis Appraisal Basis A document that defines the requirements to be fulfilled during the project Appraisal stage in order to be qualified to apply for a Storage Permit. Appraisal Plan A document that describes the scope of each step in the Appraisal stage and the activities to be carried out. Appraisal Risk Assessment A report that documents the activities undertaken during the Appraisal stage risk assessment. Report Appraisal stage The second project life cycle stage in a CO 2 geological storage project. Appraisal Report A report that documents the activities undertaken during the Appraisal stage, which storage sites are qualified to apply for a Storage Permit and the evidence for making this decision. Biosphere Realm of living organisms in the atmosphere, on the ground, in the oceans and seas, in surface waters, and in the subsurface at depths above which water salinity is less than limits defined for groundwater. See also Groundwater. Capacity Accumulated mass of CO 2 that can be injected into injection zone(s) while maintaining storage integrity. Capillary entry pressure The capillary pressure at which the non-wetting phase starts to displace the wetting phase, usually brine, contained in the largest pore throat within a water-wet formation. Carbon dioxide (CO 2 ) Non-polar chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom (O=C=O). Cement plug Volume of cement slurry placed in a wellbore which, once in a solid state, shall function as a well barrier. Characterization Report A report that documents the storage site characterization activities that have been carried out, which storage sites remain prospective and that the storage site characterization is sufficient to support the selection of a final storage site. Closure see Storage site closure. Closure Basis A document that defines the requirements to be fulfilled during the project Closure stage in order to be able to regard a storage site as qualified for Closure. Closure Plan One component of a Storage Development Plan. It is a document that describes closure requirements for a given storage site and the qualification process that shall be used to demonstrate fulfillment of these requirements. Closure Permit Written decision issued by a designated regulatory authority authorizing closure of a CO 2 storage site. Closure Qualification One component of a Storage Closure application. It is a document that includes a description Statement of the Closure Basis, an Environmental Statement for storage site closure, a Storage Performance Forecast for storage site closure, a Monitoring Plan for storage site closure and an updated Closure Plan. CO 2 Carbon dioxide. As used in this RP it assumes that carbon dioxide is pressurized; may or may not contain water; exists either as a liquid, super critical fluid or a gas; and also includes carbon dioxide dissolved in water contained in the reservoir. CO 2 geological storage CO 2 injection accompanied by storage of injected CO 2 streams in a geological formation. CO 2 geological storage project CO 2 injection CO 2 plume CO 2 stream Component of a carbon capture and storage project that includes site screening, selection and appraisal, permitting, design and construction of site facilities, well drilling, operation of CO 2 geological storage, storage site closure (including well and facilities abandonment), and post-closure. It also includes monitoring during all project phases. Well operation injecting a CO 2 stream into a designated injection zone. Dispersing volume of CO 2 stream not dissolved in resident formation fluids. A flow of substances which consists of a sufficiently high fraction of CO 2 and sufficiently low concentrations of other substances to meet specifications of streams permitted for longterm CO 2 geological storage.

9 Sec.3 Definitions and abbreviations Page 9 Term Communication Plan Consequence Consequence category Containment Corrective control Dense phase conditions Economic receptor Elevated pressure Environmental receptor Definition One component of a Storage Development Plan. It is a document that shall describe when and how the operator shall communicate with project stakeholders including providing information about environmental impact and risk treatment. Outcome of an event affecting objectives A subject of concern for which risk is evaluated and managed, for example human health and safety, environmental protection and storage site performance. Prevention of leakage at rates or in total mass sufficient to cause adverse impact. Mitigative control intended to limit the scale and duration of unintended consequences, such as leakage or pressure build-up in unintended zones or above desired levels, and to restore the integrity of a storage site and/or the quality of economic or environmental receptors that have been affected by the CO 2 geological storage project. Conditions for which CO 2 will be in a liquid or supercritical phase. Subsurface domain or formation that is or has potential to be an economic resource, e.g., hydrocarbon reservoirs, coal seams, formations with high geothermal energy conversion potential, mineral resources, etc. Pressure sufficient to cause movement of formation fluids from the storage complex through a high permeable pathway into an economic or environmental receptor above the storage complex. Biosphere, surface area above storage site or other subsurface domain or formation designated for conservation purposes that may be polluted or negatively impacted by the CO 2 geological storage project. Environmental Statement One component of a Storage Development Plan. It is a document that documents the outcome of an Environmental Impact Assessment or an equivalent process. Event Discrete occurrence or change of a particular set of circumstances over a short period of time. Event-consequence Chain of circumstances upon which a consequence with negative impact on a risk category scenario may arise as a result of the event. Failure mechanism The physical, chemical or other process that may lead to, or has led to, a failure. Failure mode Potential or observed manner of failure on a specified level of a well component or system of components. Flowline A surface pipeline carrying an injection or production stream that connects the wellhead to a manifold or to injection or production facilities, such as a compressor. Formation fluid Fluid or gas occupying pore-space in a geological formation. Fracture A crack or surface of breakage within rock not related to foliation or cleavage in metamorphic rock along which there has been no movement. Geological fault A displacement of rocks along a shear surface. The surface along which displacement occurs is called the fault plane (often a curved surface). Geomechanical stability Prevention of adverse impact caused by induced seismicity, fracturing or earth deformation as a result of CO 2 injection. Geosphere The solid earth below the ground surface and bottom of rivers and water bodies on land, and below the sea bottom offshore. Groundwater Water located beneath the ground surface and characterized by having low concentrations of dissolved salts and other total dissolved solids. Impact hypothesis Concise statement of the expected consequences both positive and negative to the risk categories of the storage site contingent upon execution of the risk management plan. Injection and Operating One component of a Storage Development Plan. It is a document that includes the final Well Plan Engineering Concept and final Well Qualification Report for each well at a storage site and describes the following characterisitics; i) the expected injection forecast, ii) the expected variation in delivered well performance and iii) well operating procedures. Injection zone A geologic formation, group of formations, or part of a formation into which CO 2 is or will be injected for the purpose of long-term storage. Injectivity (1) The possible CO 2 injection rate that can be achieved through a specified well subject to (bottom-hole or other) injection pressure constraints. Injectivity (2) The possible CO 2 injection rate for a given storage site that can be achieved subject to reservoir pressure or other injection pressure constraints. Leakage Measurable release of CO 2 stream constituents or displaced formation fluid from a storage complex that detrimentally impacts an economic or environmental receptor as a result of project activity. Leakage pathway Natural or engineered feature or combination of features through which CO 2 stream constituents or formation fluids displaced by CO 2 injection can potentially migrate outside of the storage complex. For example geological faults, wells, permeable horizons, outcrops and spill points.

10 Sec.3 Definitions and abbreviations Page 10 Term Definition Level of risk Magnitude of a risk or combination of risks, expressed in terms of the combination of consequences and their likelihood. Likelihood Chance of something happening expressed either qualitatively or quantitatively and described using general terms or mathematically, such as a probability or a frequency over a given time period. Life cycle of a storage site Time span from initial planning and execution of storage site screening to post-closure stewardship phase (see Storage site closure). Long-term Minimum period of retention of injected CO 2 -streams in subsurface geological formations necessary for CO 2 geological storage to be considered an effective and environmentally safe climate change mitigation option. Mitigative control Risk control to prevent or reduce adverse effects of events. Modelling Report A report that documents the activities undertaken during the modelling step of the Appraisal stage and the results obtained. Monitoring Measurement and surveillance activities necessary for ensuring safe and reliable CO 2 geological storage. Monitoring Plan One component of a Storage Development Plan. It is a document that describes the monitoring objectives, targets, techniques and activities for a storage site. Monitoring target A measurable physical property or characteristic at a given location that can provide an indicator of compliance or non-compliance with defined requirements for storage site performance. Operator Natural or legal, private or public person, business organization(s) or government entity who operates and controls the CO 2 geological storage operation or to whom decisive power over the storage operation has been delegated according to regulations. Overburden Sedimentary succession (stratigraphic column) overlying a reference underground formation. Plug and Abandon Action taken to ensure permanent isolation of fluids and pressures from exposed permeable zones along well trajectory by installation of well barriers, usually cement plugs. Passive control Risk control naturally inherent in the CO 2 geological storage site or in the engineered components associated with the system. Performance margin Margin to non-compliance with performance requirements. Performance requirement Requirement used to evaluate the success of a performance assessment. Permeability Measure of the ability of a soil or rock to transmit fluids. Porosity Ratio of the volume of void pore space in the rock relative to the bulk volume of the rock. Preventive control Risk control to prevent or reduce the likelihood of an event. Qualification A process of providing the evidence that a technology or CO 2 storage site will function within specific limits with an acceptable level of confidence. Regulator Relevant national, state or provincial authority and/or international regulatory body. Risk Effect of uncertainty on objectives. Risk may be expressed in terms of a combination of a likelihood of occurrence of an event and the associated severity of potential consequences that may arise as a result of the event. Risk analysis Process to comprehend the nature of risk and determine the level of risk. Risk assessment Overall process of risk identification, risk analysis and risk evaluation. Risk control Measure or inherent characteristic whose purpose is to reduce risk. Risk evaluation Process of comparing the results of risk analysis with the evaluation risk criteria to determine whether the risk and/or its magnitude are/is acceptable or tolerable. Risk evaluation criteria Terms of reference against which the significance of a risk is evaluated. Note that this definition is equivalent to the definition of risk criteria in ISO Risk identification Process of finding, recognizing and describing risks. Risk Management Plan One component of a Storage Development Plan. It is a document that describes how risks to a storage site shall be managed in the Operate and Close stages of a project. Risk owner Person or entity with the accountability and authority to manage the risk. Risk performance target For a specified risk, the target level of risk to be achieved through implementation of a prescribed risk treatment. Risk scenario Combination of a threat-event scenario and possible event-consequence scenarios. Risk treatment Process to modify risk through implementation of risk controls. Seal Relatively impermeable rock, commonly shale, anhydrite or salt that forms a barrier or seal above and around reservoir rock so that fluids cannot migrate beyond the reservoir. The permeability of a seal capable of retaining fluids through geologic time is typically in the range 10-6 to 10-8 Darcies.

11 Sec.3 Definitions and abbreviations Page 11 Term Screening Basis Screening Plan Screening stage Screening Report Significant event Significant risk Spill point Definition A document that defines the requirements to be fulfilled during the project Screening stage in order to be able to regard a storage site as prospective and thereby qualified for appraisal. A document that describes the scope of each step in the Screening stage and the activities to be carried out. The first project life cycle stage in a CO 2 geological storage project. A report that documents the activities undertaken during the Screening stage presents the evidence for selecting prospective storage sites that qualify for appraisal. Circumstance or set of circumstances with potential to have significant impact on a consequence category. Risk whose magnitude must be reduced through implementation of appropriate risk treatment to maintain alignment with project objectives. Structurally lowest point in a structural trap that can retain buoyant fluids. Stakeholder Individual, group of individuals, or organization whose interests are substantially affected by the project. Stakeholders can include employees, shareholders, community residents, suppliers, customers, non-governmental organizations, governments, regulators, labour unions, and other individuals or groups. Storage complex Subsurface volume delineated by the operator and approved by the regulator for the purpose of environmentally safe long-term containment of injected CO 2 streams. Storage Development Plan A generic term used in this document to refer to the package of documentation that an operator shall submit to a regulator in order to apply for a Storage Permit. Comparable to a Plan for Development and Operations for hydrocarbon fields. DNV recognises that the name of this document and required content may vary depending on jurisdiction. Storage integrity Ability of storage complex to provide long-term containment and geomechanical stability when CO 2 geological storage operations are managed in accordance with the Injection and Operating Plan. Storage Performance Forecast Storage permit Storage site Storage site closure Stratigraphic column One component of a Storage Development Plan. It is a document that provides a scenariobased storage performance forecast that demonstrates the suitability of the Injection and Operating Plan in meeting the storage site performance requirements defined in the Appraisal Basis. Written decision issued by a designated regulatory authority authorizing CO 2 injection by an operator into a specified injection zone for the purpose of permanent containment within a defined CO 2 geological storage complex, and which specifies the conditions under which CO 2 injection and storage operations may take place. Storage complex and the wells and surface facilities associated with the operation, monitoring and risk management of the storage site. Milestone in the CO 2 geological storage project after cessation of CO 2 injection upon which operation changes from actively managing risks through cycles of modelling, monitoring and risk assessments, to a post-closure stewardship phase focusing on providing continued assurance that risks are maintained at an acceptable level. Sedimentary succession of geological formations in region of interest for CO 2 geological storage. Technical Appraisal Plan A document that shall describe how storage site characterization and modelling activities will be performed for each prospective storage site in order to provide the technical basis for the storage site and well engineering concept selection. Threat Element which alone or in combination has the intrinsic potential to give rise to risk. Threat-event scenario Chain of circumstances upon which the threat may cause the event to occur. Verification Confirmation by examination and provision of objective evidence that specified requirements have been fulfilled, usually a quality assurance process of determining compliance with a regulation, standard or specification. Well barrier Envelope of one or several dependent components preventing fluids or gases from flowing unintentionally between geological formations or to the surface. Well component Individual pieces of equipment which are joined together as part of well construction. Well Engineering Concept A document that describes the well engineering solution for new and existing wells at concept level for a prospective storage site. Well integrity The ability of a well to perform its required function effectively and efficiently whilst preventing uncontrolled release of formation fluids along the wellbore throughout the life of the well. Well Qualification The process of providing the evidence that a given well will function within specific limits with an acceptable level of confidence. Well Qualification Basis A document that defines the requirements to be fulfilled during the qualification of a given well, including a description of the current status of the well, the well performance requirements, the well specification and the critical parameters.

12 Sec.3 Definitions and abbreviations Page 12 Term Definition Well Qualification Report A report that documents the activities performed during Well Qualification, the fitness for purpose of a given well and the defined margins against specified failure modes or performance targets. Wellbore The physical hole that makes up the well. 3.2 Abbreviations ALARP As Low as Reasonably Practicable CCS Carbon Capture and Storage CO 2 Carbon Dioxide HSE Health, Safety and Environment. 3.3 Verbal Forms For verification of compliance with this RP, the following definitions of the verbal forms, shall, should and may are applied: Shall: indicates a mandatory requirement to be followed for fulfilment or compliance with the present RP. Should: indicates a recommendation that a certain course of action is preferred or particularly suitable. May: indicates permission, or an opinion, which is permitted as a part of conformance with the RP.

13 Sec.4 Storage Site Screening and Appraisal Page 13 4 Storage Site Screening and Appraisal 4.1 Introduction This chapter describes the recommended procedure for identifying potential storage sites in a given region, screening those that are prospective and developing one or more to a level of maturity suitable for beginning the process of applying for a Storage Permit at Milestone M3 in Figure Screening General The purpose of storage site screening is to evaluate the potential for CO 2 geological storage in a given region. The following steps represent a generic recommendation of screening activities applicable to any region. The scope of the steps is expected to vary between regions depending on the quality and quantity of existing data. The output from storage site screening should be a list of potential storage sites that fulfil the operator s requirements laid down in the Screening Basis. The screening process shall be documented in a Screening Report Screening Basis The purpose of the Screening Basis is to provide a common set of requirements against which all potential storage sites will be assessed at Milestone M2 in Figure 2-1. The Screening Basis document should include a list of requirements that a storage site should fulfil in order to be regarded as prospective and qualify for appraisal. These requirements should at least include those listed in Table 4-1. Table 4-1 Requirements to potential storage sites that should be included in the Screening Basis 1) A quantitative requirement for minimum total capacity (tonnes) 2) A quantitative requirement for minimum annual injectivity (tonnes/year) 3) A requirement for documented evidence of the following positive indicators of long-term containment: 4) A requirement for documented evidence of the following positive indicators of the potential to monitor and deploy risk treatment: The Screening Basis document should also describe the context in which the screening activity is taking place. The context may be described by the following: the locations of the current or planned sources of CO 2 the mass rates and composition of the CO 2 streams from these sources the expected rates of supply and the lifetime of the CO 2 sources the natural environment such as meteorology, surface/marine environment, biosphere, hydrosphere and geosphere in as far as it may interact with the storage complex or potential leaks from the complex historical, existing or planned uses of the subsurface in the region, such as: groundwater extraction oil or gas production geothermal energy extraction acid gas disposal natural gas storage waste disposal a) depth: sufficient depth of injection zone to achieve CO 2 dense phase conditions (> 300 kg/m 3 at reservoir conditions) b) seal: presence of laterally extensive seal above the injection zone to prevent flow communication with economic and/or environmental receptors c) wells: confidence that well integrity can be established and maintained in existing wells that penetrate the primary seal and will be exposed to CO 2 or pressure changes i) sufficiently stable geological environment to give confidence that containment will not be jeopardized by d) geological faults: natural tectonic activity ii) absence of existing flow-paths along geological faults that penetrate the storage complex a) legal availability of the storage site over the expected life cycle b) physical accessibility to the storage site over the expected life cycle historical, existing or planned land use in the region for onshore storage sites, such as: population centres (taking into account demographic trends)

14 Sec.4 Storage Site Screening and Appraisal Page 14 industrial developments agriculture transport infrastructure such as roads and railways industrial infrastructure such as pipelines and power lines protected and sensitive areas such as: nature reserves (on land or marine) indigenous reserves military areas drinking water sources the social and cultural context around a storage site, including public perceptions of CO 2 geological storage and related issues in the region the legal and regulatory environment for CO 2 geological storage in the region the expectations of the operator, regulators and stakeholders to the screening process Screening Plan The purpose of the Screening Plan is to describe the scope of each screening step and the activities to be carried out. The planned activities should be appropriate for the type of data that will be used and the level of detail required for comparison against the requirements set out in the Screening Basis. The Screening Plan document should describe the following: the data that will be used for screening where this data will be obtained how this data will be used to identify potential storage sites how storage capacity will be calculated how existing wells will be identified and risk assessed how other potential leakage risks will be identified and risk assessed how potential conflicts with other sub-surface resources or land-use claims will be identified how the location of potential storage sites will be evaluated with respect to the location of CO 2 sources which stakeholders will be involved or informed during the screening process stakeholder s needs for information and involvement, providing the rationale for the communication strategy and for future engagement how legal and physical accessibility to storage sites will be assessed Data Collection and Review The purpose of this step is to collect and review data in order to identify potential storage sites. This activity may primarily be based on data available from existing sources, but acquisition of new data through early-stage appraisal activities may be needed in data poor areas. An operator should consider the likelihood of getting necessary public support for undertaking CO 2 storage in a given region, which may entail public surveys and stakeholder interviews. Data review should identify geological structures that demonstrate the potential to comply with the requirements in the Screening Basis and document these as potential storage sites. Examples of the types of data that may be collected and the information that may be derived from each are given in Appendix A. Guidance note: For regions with a large number of possible storage sites, this step may require an iterative approach that may use indicative storage site screening requirements as a first step. Such requirements may be used to rank storage sites according to suitability for CO 2 storage. Geographical Information System tools and datasets may be utilized to facilitate recording and visualization of such ranking parameters. The main purpose of screening requirements is to enable compilation of aggregate ranking scores indicative of storage site suitability to help accelerate and guide the screening process by rapidly identifying the most promising areas for CO 2 geological storage. Screening requirements should not be interpreted as thresholds for elimination of prospects with unfavorable characteristics. The suitability of a potential storage site will ultimately need to be demonstrated through detailed storage site-specific assessments. To this end, storage sites with certain unfavorable characteristics may in the end still prove to be suitable. Furthermore, while generic screening requirements may be applied to assign indicative suitability scores, additional requirements may be added to reflect the purpose of the storage site, including potential social, cultural, technical or economic constraints. For further information about screening requirements see: IEA Greenhouse Gas R&D Programme (IEA GHG) CCS Site Characterisation Criteria, Report No. 2009/10. Cheltenham. United Kingdom. ---e-n-d---of---g-u-i-d-a-n-c-e---n-o-t-e---

15 Sec.4 Storage Site Screening and Appraisal Page Uncertainty Assessment General The purpose of this step is to assess the level of uncertainty related to each potential storage site that was identified in the preceding step. The quality and quantity of the available evidence for and against meeting the requirements laid down in the Screening Basis should be assessed for each potential storage site. Critical pieces of missing information that would reduce the uncertainty for a given storage site should also be identified and recorded for use in developing an eventual Appraisal Plan Capacity Initial estimates of storage capacity can be obtained using a number of different methods that span a range of complexities. Three broad groups of capacity estimation methods are volumetric methods, analytical or semianalytical methods, and numerical reservoir simulation methods. For these categories the uncertainty attached to capacity estimates may be assessed by using the following approaches: for volumetric based capacity estimation methods the uncertainty may be reflected by providing conservative and optimistic estimates of the volumetric fraction of the pore-space that can be filled with CO 2. For closed contour structures the capacity is usually not more than 1-2 percent of the accessible porevolume due to limits on pressure build-up. (Note that this ratio may be significantly increased if the reservoir has been depleted by hydrocarbon production). Other factors, such as preferential flow paths and internal flow barriers, may further reduce the capacity. for capacity estimation methods that include modelling of the CO 2 plume movement and pressure build-up in an analytical or semi-analytical fashion it may be possible to do sensitivity analysis of the primary uncertain parameters that describe the pore volume of the target storage formation and possible degree of filling with CO 2 if three-dimensional reservoir simulations are applied to estimate capacity, then the level of uncertainty may be estimated by simulating a limited number of scenarios, including best-case and worst case scenarios. The level of uncertainty will also be reflected by the complexity of the method used to estimate capacity and the reliability and resolution of the data from which the storage capacity has been estimated Reservoir injectivity Early estimates of reservoir injectivity may be based on permeability measurements or calculations from regional well-logs or production/injectivity data of existing wells in the injection zone. The uncertainty in reservoir injectivity is often related to the availability of well-logs in the vicinity of the proposed storage site. Other key uncertainty factors with regards to reservoir injectivity are the potential for compartments or flow baffles in the target formation and the effect of near-well geochemical reactions that may limit the sustained injectivity of a given well. These factors are, however, generally difficult to assess at the screening stage unless the storage site has been subject to oil or gas development Containment At the screening stage containment is typically assessed based on the formation type, depth, thickness, and lateral extent of the primary seal above the target storage formation, as well as the density, depth, age, data availability and drilling, construction and abandonment procedures for active and abandoned wells in the region. Consideration should also be given to the potential for natural or induced seismic events to create leakage pathways. Key containment uncertainties relate to the degree and certainty of knowledge about these parameters and the contribution from the four different trapping mechanisms (structural, capillary, solubility, and mineral trapping) during the life cycle of the storage site. To evaluate the significance of the uncertainties, the redundancies in the containment system (for example the presence of multiple geological seals and number of independent well barriers) should be taken into account. Guidance note: Assessment of injectivity is also partly a commercial consideration since lack of reservoir injectivity can often be managed by increasing the number of injection wells. Depending on the availability of data, the assessment of the requirements defined in the Screening Basis may entail acquisition of data not readily available (e.g., through drilling and collecting logs from an appraisal well) and dedicated modelling efforts. The need for acquisition of additional data should balance the benefit of reducing uncertainty against the cost of the data acquisition. Similarly the need for and scope of modelling efforts at this stage should reflect the need for sufficiently robust assessments of capacity, injectivity and containment characteristics to support the prioritization of storage sites for further characterization. ---e-n-d---of---g-u-i-d-a-n-c-e---n-o-t-e---

16 Sec.4 Storage Site Screening and Appraisal Page Risk Assessment The purpose of this step is to develop an initial risk register for each potential storage site within the context of the preceding uncertainty assessment. The initial risk register should be used for comparison in the following selection step and should be suitable for independent audit and verification. See Sec.6.3 for a risk assessment method description tailored to potential storage sites. See Sec.7.3 for specific considerations with respect to existing wells. This step represents the first risk assessment for the storage sites being screened and the resulting risk register should form the basis for documenting the history of successive risk assessments. An electronic risk database is recommended over a simple spreadsheet in order to keep track of changes over time and manage actions and responsibilities related to individual risks or groups of risks. The risk register should describe the methodologies and tools applied to assess and manage risks, define the consequence categories and describe the risk evaluation criteria for each consequence category tuned to the scope and objectives of the project. The risk evaluation criteria can entail the use of qualitative or quantitative likelihood and consequence classes. For each identified risk, the initial risk register should contain the following information from the risk assessment: a description of the potential causes and consequences of the risk the estimated likelihood and severity of potential consequences before risk treatment preferred risk controls the estimated likelihood and severity of potential consequences after preferred risk controls are implemented together with an explanation of the basis for the risk evaluation the names of the people assigned with responsibility to implement preferred risk controls the risk owner. Revisions to the risk register should be documented in a transparent and traceable way. This includes documenting the basis and rationale for revisions, the date that specific revisions were made, and by whom. The risk register should also track the effect of implemented risk treatment, also when the effect is in accordance with prior assessments of its effectiveness Milestone M2: Screening Report and Selection of Prospective Storage Sites The purpose of this step is to select prospective storage sites from a ranked list of potential sites and document the screening process in a Screening Report. Each storage site should be evaluated against the requirements in the Screening Basis. The screening activities should be evaluated against those described in the Screening Plan and the check-list in Table 4-2. The following components should be collated in a Screening Report, which should highlight uncertainties and constraints that might be put on injection at each storage site: Screening Basis document Screening Plan document data collection and review findings uncertainty assessment findings risk assessment findings evaluation against the requirements in the Screening Basis. If the evaluations are positive for a storage site then it should be regarded as prospective and thereby qualified for storage site appraisal. If more than one storage site is prospective, the operator should take into account the results of the preceding uncertainty and risk assessments in order to prioritise subsequent appraisal work.

17 Sec.4 Storage Site Screening and Appraisal Page 17 Table 4-2 Screening check-list Is the regulatory process and the requirements for CO 1 2 geological storage in the target region understood by the relevant competent personnel? Have all applicable legal and regulatory constraints been identified, e.g., surface/subsurface access and 2 ownership, areas excluded from storage, trans-boundary issues and access for future field studies, such as seismic surveys? Legal, regulatory, social and commercial Geology and Environmental Risk 4.3 Appraisal General Have all social and cultural constraints that may impede the likelihood of project approval/acceptance 3 been identified and assessed, including public perceptions of CO 2 geological storage and related issues in the region? 4 Have all potential conflicts of use of the surface and subsurface at the target region been identified? 5 Have the sources, volumes and compositions of the CO 2 streams to be injected and stored been adequately defined? 6 Have opportunities for cost-effective transport from source to sink been adequately assessed? Has the stratigraphy at each storage site been compiled and documented? Have all potential storage reservoirs, primary seals and formations that may represent a conflict of interest been identified? For example hydrocarbon or groundwater bearing formations. 7 Have structural and isopach maps of injection and confining zones been examined? For example regional cross sections and tectonic maps. Has the regional hydrogeology been studied? Has sufficient data on the injection zone(s) been compiled and reviewed, including depth, thickness, 8 reservoir dip, lithology, pressure, temperature, porosity, permeability, salinity, mineralogy, interstitial shale content and potential rock-fluid interactions? Has sufficient data on each confining zone been compiled and reviewed, including depth, thickness, 9 areal extent, lithology, capillary pressure data, and other factors that may affect integrity of the confining zone(s)? Does the data reviewed on the confining zone(s) (for example fracture strength) provide adequate 10 confidence in the ability to ensure containment of injected CO 2 streams to enable the decision to invest in further storage site characterization? Are the contributions from the four trapping mechanisms adequately understood at this stage of the 11 project? Has storage capacity and injectivity of each potential storage site been estimated and the level of 12 uncertainty in these estimates been quantified? Have all existing wells within each of the delineated areas for the potential storage sites been identified 13 and the corresponding well completion logs and well records been obtained? Has the industrial history of the potential storage sites been reviewed, e.g., mining, groundwater 14 production, disposal of waste, natural and town gas storage, well abandonment history? 15 Have all environmental and economic receptors surrounding the potential storage site been identified? Has relevant environmental data required for screening been acquired and reviewed, e.g., maps or 16 regional groundwater, surface water, sensitive terrestrial and marine ecosystems, and land use (for onshore storage sites)? Ability to monitor the storage site: has it been established that there are no obvious barriers to effective 17 monitoring? 18 Have all relevant consequence categories been defined? 19 Are the project specific risk evaluation criteria for the respective consequence categories appropriate? 20 Does the risk register comprehensively document how risks have been assessed for each element of concern? Is the basis and rationale for the evaluation of identified risks documented in a sufficiently transparent 21 way to support differentiation of potential storage sites based on legal, regulatory, technical, commercial, social and cultural factors? The purpose of this stage is to appraise prospective storage sites in detail and develop a well engineering concept that provides the required capacity, injectivity and containment. Appraisal should be carried out for a portfolio of prospective storage sites in order to minimise the risk of not discovering a suitable storage site in a given area. The storage site appraisal process shall provide an operator with enough technical information to determine which storage sites remain prospective at Milestone M3 in Figure 2-1 and select the best candidate. The appraisal process shall be documented in an Appraisal Report. If successful, the appraisal process shall provide the information required to compile a robust Storage Permit application.