Worst Case Discharge (WCD)

Transcription

1 U.S.A. Israel Workshop EIGOA Wohl Center, Bar-Ilan, Ramat-Gan, Israel July 22-25, 2012 Worst Case Discharge (WCD) Thierry M. De Cort United States Department of the Interior Bureau of Ocean Energy Management

2 WCD NTL 2010-N06 June 18, 2010 Worst Case Discharge The daily rate of an uncontrolled flow from all producible reservoirs into the open wellbore. The package of reservoirs exposed to an open borehole with the greatest discharge potential will be considered the worst case discharge scenario. Shallower producible reservoirs isolated by casing and cement will not be considered in the uncontrolled flow. 3 Producible reservoirs

3 BSSE Regulatory Plans WCD Regulatory Definition (OSRP) BSEE Regulation for Determining Volume of WCD 30 CFR (3)(b) For exploratory or development drilling operations, the size of your WCD scenario is the daily volume possible from an uncontrolled blowout. In determining the daily discharge rate, you must consider any known reservoir characteristics. If reservoir characteristics are unknown, you must consider the characteristics of any analog reservoirs from the area and give an explanation for the selection of the reservoir(s) used

4 BOEM Regulatory Plans AUTHORITY TO REQUEST INFORMATION FOR WORST CASE DISCHARGE 30 CFR (g) an Exploration Plan (EP) must be accompanied by a blowout scenario description. 30 CFR (h) requires the same for a Development and Coordination Document (DOCD). 30 CFR and , all plans must also be accompanied by information regarding oil spills, including calculations of your worst case discharge (WCD) scenario.

5 BOEM / BSEE Regulatory Plans and Documents Before an operator can conduct any activity on a lease or unit, they must submit an activity plan for approval: Exploration Plan (EP) Document submitted to conduct any exploration activities on a lease or unit Development and Production Plan (DPP) Document submitted to conduct any development and production activities on a lease or unit in any area other than the Western GOM planning area Development Operations Coordination Document (DOCD) Document submitted to conduct any development and production activities on a lease or unit in the Western GOM planning area

6 Worst Case Discharge Scenario Provide Blowout Scenario of: Exploration Plan (EP) Development and Production Plan (DPP) Development Operations Coordination Document (DOCD) well with highest potential volume (includes volume, flow rate and duration) 30CFR (g) WCD Scenario of Oil Spill Response Plan (OSRP) Scenario is daily flow volume over a 30-day period and includes a trajectory path) 30 CFR Oil Spill Financial Responsibility is based on the WCD

7 Exploration Plan WCD Example Category Regional OSRP (Exploration) EP Type of Activity Exploration Drilling Exploration Drilling Facility Location XX xxx XX xxx Facility Designation MODU MODU Distance to Nearest Shoreline Volume of Uncontrolled Blowout (per day) miles 300, ,000 Type of Oil(s) Crude Oil Crude Oil API Gravity (estimated)

8 Worst Case Discharge Premise Operator responsibility to determine WCD Verification of operator submitted analogs, assumptions, and calculations through independent analysis Proprietary and non-proprietary data from corporate database used for verification Verification of parameters assuming a best case exploration mode

9 Worst Case Discharge Premise Water sands can be included if there is offset data to support it and if they are above the deepest pay sand BOEM does not consider bridging Assume all casing strings are successfully run and cemented above zone that is flowing Assume flow is up unobstructed casing and liner no drill pipe in the hole WCD calculated at location of BOP stack

10 A Multi-Disciplinary Approach BOEM Plan Coordinator in Leasing and Plans notifies Resource Evaluation (RE) of Plan Submittal Geoscientist Assignment RE Pre-Review Team Engineer s Assignment Pre-Review Team Screen data for completeness If incomplete, notify Plans Check seismic data for adequate coverage Verify operators maps and analogs Identify/determine the Potential Producible Hydrocarbon Sands exposure to wellbore for WCD calculation Provide engineer with G&G data Generate Geologic Report Review WCD scenario from plan Determines if supplied data is insufficient Gather reservoir and PVT data Planimeter isopachs Review proposed well schematic Run Merlin simulation model Run Avalon nodal analysis Generate Engineer Review Report Geoscientist Assignment Engineer s Assignment Post-Review Operator s Post-Submittal If BOEM WCD calculation is greater than operator s WCD, then the Operator has the option to submit additional data in support of their assumptions, analogs, and calculations for to Plans Coordinator. Plans notifies Reserves Staff of receipt of additional data.

11 Rationale for Detailed WCD Analysis Essentially same process used for Flow Rate Technical Group Reservoir Team Regulations indicate a site specific WCD based on reservoir and rock characteristics WCD volume is defensible for operators appeal, litigation or FOIA requests Process peer reviewed by U.S Geological Service

12 BOEM Worst Case Discharge Data Sources Data submitted in Plans in support of Operator s WCD scenario Analog drilling or production data, rock and sand strength, formation age, variance in pore pressures, etc. Operator s submitted data not associated with WCD Logs, Cores, Pressure Data, and Production Data Corporate database (TIMS) reservoir properties and sand characteristics derived by Reserves Section

13 BOEM- Form 0137 Effective: January 2012 BOEM Worst Case Discharge Data Sources BOEM-0137 provides tables for the operator to submit geologic and engineering parameters for the well with the highest worst case discharge volume. ( Worst Case Discharge (WCD) Well Information WCD Well Name Surface Lease Surface Area/Block Bottom Lease Bottom Area/Block Product Type MD TVD Analog Well(s) Area/Block OCS Lease Well No. API No.

14 BOEM- Form 0137 Effective: January 2012 BOEM Worst Case Discharge Data Sources Geologic Data for WCD includes: Open Hole Interval for WCD Top (TVD in feet) Base (TVD in feet) Formation Data Sand 1 Sand 2 Sand 3 Sand 4 Sand 5 Sand Name Estimated Top TVD Estimated Base TVD Estimated Net Sand Height MD (Net Pay if hydrocarbon) Estimated Net Sand Height TVT (Net Pay if hydrocarbon) Fluid Type Used in WCD? (Yes/No) Seismic Survey Used

15 BOEM- Form 0137 Effective: January 2012 WCD (STB/Day) BOEM Worst Case Discharge Data Sources Engineering Data for WCD includes: WCD Calculated at Mudline y/n Atmosphere y/n Flow Correlation Outlet Pressure (Psia) Gas Turbulence Factor Software Model Used Formation Data Sand 1 Sand 2 Sand 3 Sand 4 Sand 5 Sand Name Permeability Initial Pressure Reservoir Temperature Porosity Water Saturation Rock Compressibility Water Salinity Drive Mechanism Drainage Area

16 BOEM Worst Case Discharge Data Sources Oil and Gas Reservoir Data for WCD includes: Oil Reservoir Data Sand 1 Sand 2 Sand 3 Sand 4 Sand 5 Bubble Point Pressure (PSIA) Initial Bo (RB/STB) Bo Bubble Point Rsi (SCF/STB) Initial Oil Viscosity (Cp) Oil Viscosity Bubble Point Oil Compressibility (1/PSIA) Oil API Gravity (API) Specific Gas Gravity (0.00) Gas Reservoir Data Sand 1 Sand 2 Sand 3 Sand 4 Sand 5 Condensate API Gravity (API) Specific Gas Gravity Yield (STB/MMCF)

17 BOEM- Form 0137 Effective: January 2012 BOEM Worst Case Discharge Data Sources Permeability Data Data for WCD includes: Source of Permeability Used Permeability from MDT Permeability from Core Analysis Percussion core Rotary sidewall core Conventional core Pressure Transient Analysis Permeability from log analysis Permeability from other source Provide Model Input Values for Relative Permeability: Residual Oil to Gas fraction (=1-Slc-Swc) Residual Oil to Water fraction (=Soc) Critical Gas fraction (Sgc, Gas/Oil-Water Systems) Residual Gas to Water fraction (Sgc, Gas/Gas-Water Systems) Kro Oil Curve Endpoint (fraction of absolute permeability) Krg Gas Curve Endpoint (fraction of absolute permeability) Krw Water Curve Endpoint (fraction of absolute permeability)

18 VERIFICATION OF SELECT GEOLOGIC PARAMETERS

19 Example of Verification Forms

20 WCD Methodology - Geology Review all Available Maps, In-House Seismic Data, and Corporate Database to Select Analogs; Determination of all Potentially Producing Hydrocarbon Sands (PPHS), Water Sands, and the Geologic Age and Thickness of all PPHS; Review of Operator Targets and Analogs;

21 WCD Methodology - Geology BOEM Responsible for: Verification of Operator Submitted PPHS Reservoir(s) Reservoir Maps and Reservoir Volume; Verification of Reservoir Depths, Thickness and Fluid Contacts for all PPHS and Water Sands; Verification of Analog Review Stage 1 - WCD Geoscientist / Engineer Team Stage 2 - WCD Team Supervisor Stage 3 - WCD Committee

22 Analog Selection Example Unstable Early Miocene Salt Withdrawal / Mini-Basin Fill Stable Early Miocene Platform Area of WCD Red = Thinner Blue = Thicker Company s sand thickness estimates may have been influenced by sands deposited in early Miocene subsiding basins.

23 Potential Producible Hydrocarbon Sands Identified by the Operator

24 Operator Identified - Analog Well Interpretation by BOEM Petrophysical Analysis Unit

25 Operator - Casing Program PPHS A, B and C PPHS D and E

26 Verification of Producible Hydrocarbons Analog well: Reservoir A 480 ft. down dip from the proposed well Proposed well: 172 net TVT oil-filled sand expected Interval will be cased over before drilling ahead Drill out of 9 7/8 casing Reservoir Sand at ~ 21,688 TVD Top 9 7/8 casing for proposed well Reservoir B

27 VERIFICATION OF ENGINEERING PARAMETERS

28 Engineering Workflow Reservoir Simulator: Enter Rock and Fluid Properties to determine Absolute Open Flow at Reservoir Nodal Analysis: Enter Fluid Parameters Reservoir Simulator: Incorporate Tubing Curves for Well Head Flow Tubing Curve: Directional Survey, Drilling Program, Casing Design, and Open Hole Configuration WCD

29 WCD Engineering Methods Data Sources Verified Operator-Submitted Maps and In-house Structure Maps Pressure Volume Temperature (PVT) Reports: According to NTL 2008-G22 PVT data on an active lease is releasable to the Public after 10 years. Core Samples: According to NTL 2008-G22 Conventional Core data on an active lease is releasable to the Public after 10 years and Sidewall Core data is releasable after 2 years. Reservoir Modeling Software Used by BOEM Merlin and Avalon

30 Software Reservoir Data Requirements Acreage Sand depth Sand height Porosity Permeability Reservoir pressure Reservoir temperature Water saturation Gas density Oil API gravity Oil/Water contact Gas/Oil ratio Bubble point pressure Formation vol. factor Oil viscosity Separator press. and temp.

31 Estimation of Permeability Data Priority 1. Conventional Cores 2. Pressure Transient Analysis (PTA) and Repeat Formation Tester (RFT) 3. Combinable Magnetic Resonance (CMR) Log 4. Modular Formation Dynamics Tester (MDT) Log 5. Rotary Sidewall Cores 6. Percussion Sidewall Cores: Eliminate all shots that will not contribute to flow, determine the arithmetic mean of the remaining cores, then reduce by 50%

32 Review Available PVT Report(s) Determine (based on depth) Reservoir pressure Reservoir temperature Determine formation volume factor (Boi) Determine gas density Determine API gravity Determine GOR

33 Review Available PVT Report(s) Determine oil viscosity and bubble point pressure Verify API gravity, GOR, and gas gravity

34 Software Well Data Requirements Expected range of water production rates Expected range of oil/gas ratio Expected range of oil or gas production Surface pressure range Casing dimensions and weights Wellbore deviation angles Casing segments lengths, respective to angle deviation Flow correlation based on reservoir conditions

35 Apply Data to Reservoir Software

36 Hard Code Available Data or Allow the Software to Recalculate Certain Parameters

37 Create Nodal Analysis for Flow Calculation

38 Create Wellbore Nodal Analysis Using Wellbore Diagram. Input Drilling Depth, Angle Deviation, and Casing Dimensions

39 Run Software to Determine WCD WCD estimated flow rate end of day 1 Day 1= maximum rate Day 1 rate reported to BOEM WCD flow rate at 30 days

40 LESSONS LEARNED

41 BOEM - WCD Data Verification Issues of Note Operator identifies only their primary target reservoir in the open hole when more than one is present Operator s target sand(s) is deeper than shallower sands that may have a higher WCD Operator s plan submittal indicates significant deeper drilling below target sand Operator does not identify the WCD well in a multi-well Plan Operator does not consider recent non-proprietary data that could influence analysis Critical nodal analysis factors such as permeability, sand thickness, reservoir pressure and gas-condensate yield are not sufficiently documented

42 BOEM - WCD Data Verification Issues Certain software applications used by operators are not fully developed to calculate uncontrolled flow in a WCD scenario Application of sand thickness in modeling is inconsistent (MDT vs TVT) Drastic reduction of liquid hydrocarbons in gas flow based upon sonic velocity restrictions Inconsistent permeability determination methods used

43 WCD Activity as of January 2012 WCD Submittals Received: 282 WCD Verifications Completed: 270 July Dec Jan Dec Jan Request to Operator for Additional Data: 95 WCD Scenario Submitted for Deep Water Plan: 135 WCD Scenario Submitted for Shallow Water Plan: 147 Reserves WCD Greater than Operator s WCD : 107 Number of Meetings with Operators: 62 EP OSRP Verification 42/79

44 WCD Process - Peer Review USGS BOEM s definition for an uncontrolled blowout scenario, along with information on well casing/lining, provide a set of reasonable and appropriate specifications for setting up the well-flow simulation portion (i.e., nodal analysis) BOEM s use of the engineering judgment to select reservoir property values for WCD calculation is a practical and reasonable approach. Although this procedure requires subjective judgment, it can be readily explained to permit applicants. The procedure can be readily carried out by both the permit applicants and by BOEM staff. However, the existing FAQ does not discuss the uncertainty in reservoir properties Although the probabilistic treatment might require resources that are beyond what is currently available to BOEM, it should not be ignored because of its inherent benefits.

45 U.S.A. Israel Workshop EIGOA Wohl Center, Bar-Ilan, Ramat-Gan, Israel July 22-25, 2012 Thank You For The Opportunity To Speak With You Worst Case Discharge Special thanks to Blake Zeringue and Nancy Shepard for their assistance in preparing this presentation Thierry M. De Cort United States Department of the Interior Bureau of Ocean Energy Management