News Volume 1 Edition 1

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1 News Volume 1 Edition 1 Providing Insight Onsite A New Dimension to Process Mapping of Subsea Separator Vessels with The TRACERCO Profiler By Magne K. Husebø, General Manager, Tracerco Norge AS Co-authors: Dr. Paul Featonby, Tracerco UK and Ola Jemtland, FMC Technologies Over the past 50 years Tracerco has worked closely with customers to develop a range of non-intrusive measurement solutions for process diagnostics and continuous control worldwide. One such instrument that has been installed in a significant number of global assets is The TRACERCO Profiler that is used in topside projects to optimize separator control, shutdown and monitoring applications. Using knowledge gained in the design of The TRACERCO Profiler instrument Tracerco has worked in Tordis SSBI delivered to Statoil by FMC Technologies Figure 1 Illustration of The TRACERCO Profiler system set-up provided courtesy of FMC Technologies INSIDE THIS ISSUE Process Mapping of Subsea Separator Vessels...1 Reservior Near-Wellbore Tracer Studies...3 Detect Water Ingress of Jacket Members...6 partnership with FMC Technologies to design and successfully test an innovative solution for separator process control subsea resulting in The TRACERCO Profiler for use subsea (Figure 1). During the early design stages, one main concern was that critical level control and shutdown measurement systems needed to be retrievable. Dual steel walls, one for the process and one for the instrument was determined to be the solution for this design challenge. Tracerco s R&D Team combined the standard topside profiler design with traditional through-vessel radiation technology and replaced the isotope type used in the topside version with one containing more penetrating ability. The selected isotope source size and energy easily penetrates the thick steel walls and process medium, providing an instrument that is sensitive to small density variations within the process. The detector arrays are designed to be retrievable so they can be changed in the unlikely event that a fault should occur. The radioactive source arrays have no Continued on page 2 Figure 2 Illustration provided by FMC Technologies of the detector array system placement in the subsea separator. 1

2 Subsea Separator (Continued from page 1) moving parts or electronics and therefore there is no need for the option of retrievability on this part of the instrument. Figure 2 on page 1, provided by FMC Technologies, demonstrates how the design of the retrievable detector array system is safely placed into a dip pipe from top of the subsea separator. How The TRACERCO Profiler Works The TRACERCO Profiler consists of two (or three) parallel pressure sealed pipes installed vertically through a top-mounted separator nozzle (Figure 3). One (or two) pipe(s) form the detector dippipe(s), including small gamma detector segments stacked vertically in the pipe. The parallel mounted pipe contains tiny encapsulated gamma-ray sources. Each source is collimated; the narrow angled radiation beam traveling horizontally through a segment of the process fluid and being picked up by the corresponding detector in the detector pipe. The radiation signal received at each detector relates to the average process density across the distance between source and detector, at the height of which the detector is located. Density values of all detectors present are presented in a bar diagram representing the density profile of the process fluids. (Figure 4). Significant change in density represents the level of interface between process medium phases: Gas/foam interface Foam/oil interface Oil/water interface (top of oil continuous emulsion level), Water/oil interface (bottom of water continuous emulsion band) Water/sand interface Detectors are used for radiation detection. A microprocessor on top of the detector dip-pipe collects data from each detector (raw counts) and transfers data to a signal processor unit located in safe area. As well as providing density information, The TRACERCO Profiler software calculates the vertical level position for all separator Figure 3 Illustration of The TRACERCO Profiler source and detector configuration. process medium interfaces. This level information can be exported to a process control or shutdown system, as required. A SIL2 certified version of the Profiler covers safety integrity requirements for new process installations. Separator Process Mapping The TRACERCO Profiler can be used in a number of different process monitoring applications by looking at changes in the process density profile. Combination of wells, production rate, change in chemical injection and sand jetting are a few examples of the different process monitoring applications. The TRACERCO Profiler is also widely used for optimization of chemical injection of anti-foaming and de-emulsifiers chemicals: foam height and emulsion bandwidth trends logged during trials on different chemical products provide the information needed to reduce waste and improve processes. System Testing The subsea profiler has been qualified to ISO13628 with thorough qualification tests and environmental stress screening. During factory acceptance testing for subsea profilers for Continued on page 5 Figure 4 Bar Diagram representing the density profile of the process fluids. The benefits of the proven TRACERCO Profiler technology have now been taken subsea to provide the ultimate marriage between performance, reliability and the environment.... ı 2

3 Reservoir Near-Wellbore Tracer Studies Provide Enhanced Information on Oil Recovery to Deliver Optimal Production By Paul Hewitt, Vice President Americas Pasadena, Texas USA Tracerco has developed a tracer application that when applied in wells allows an oilfield operator to obtain oil flow verification from the wellbore during clean up and first oil production. This technology provides oil and gas companies the capability of confirming zonal flow within a well. In order to extract hydrocarbon reserves a number of wells need to be drilled to transport fluids from an oil reservoir to the surface. The wells are drilled to produce an open hole. In a number of cases, steel tubing is lowered into the hole and cemented in place. In other well completion arrangements, a steel screen is positioned within productive zones that allows oil flow but prevents sand from flowing into the wellbore. As drilling activities are costly, wells are designed and drilled at deviated angles. This can vary from vertical and in many cases, is branched to pass through several zones containing hydrocarbons in order to maximize use of a common bore hole to the surface. In a number of cases, drilling is carried out vertically and then horizontally for many kilometers within an oil bearing strata, allowing previously uneconomical reserves to be extracted. Once a wellbore has been drilled and production started it is crucial to ascertain oil and gas flow rate from the well but also confirm the origination of oil from the various production zones. Principles of the Technique The principle of the technology involves the positioning of a number of different tracer materials onto screens, pup joints, or perforation guns to be run to specific positions along the length of the wellbore as part of the production string or completion process. Once located at known positions the tracers remain in place until hydrocarbon flow passes their location. When this occurs the tracer material is carried with the hydrocarbon to the surface. Production sampling during clean up and first oil flow, followed by analysis for presence of tracer materials within the production fluid allows flow zones to be measured that contribute to overall production. Stable tracers are required at reservoir conditions for significant periods of time, sensitive to analysis and used in a suitable chemical form that ensures solubility in crude oil while remaining insoluble in water. Positioning Tracer Materials Within The Wellbore Two methods are used to position specific tracer materials within the completion string dependent upon completion design. In the case of screen completions the tracer is added to an oil soluble wax and then either coated to the inside of a pup joint that is used within the completion string or applied directly to an outer screen section. The wax is allowed to cure over a 24 hour time period prior to running into the hole. The wax may be applied either at the work site or prior to dispatch of the screens/pup joints from a manufacturers facility. If perforation guns are used prior to running them into the hole a number of chemical tracers are irreversibly attached to the outside of a number of individual shaped charges on Figure 9 An illustration of chemical tracers irreversibly attached to the outside of a number of individual shaped charges on specific perforation gun sections. specific gun sections (Figure 9). The chemical tracers are manufactured in a small pill form that ensures solubility in crude oil while remaining insoluble in water. Each of several different tracers may be attached to specific perforation guns to be used at horizontal intervals of most interest to the operator. Tests undertaken have shown that there is no detrimental effect on perforation gun performance due to the presence of the small pills within the scallops. Upon triggering the perforation guns the tracers are carried with the explosive pressure wave into the formation. The tracers, due to their insolubility in water will remain in the formation until first oil production. Table 1 Sampling and Analysis In order to establish the presence of flow from various positions within a well, production samples are required to be taken during clean up and first production. A number of 100ml samples are taken from the main flow line by a Tracerco Engineer or Production Operator. A typical sampling regime is one every 5 minutes for the first hour followed by once every 15 minutes, for the duration of the clean up and first oil flow back. Approximately samples are taken over a 2 day period. Wellbore Study Case Study I An operator had planned to use a bilateral well design in one well of a reservoir development to efficiently extract Continued on page 4 CHEMICAL DEPTH TO LATERAL TOP ITEM (METRES) TRACERCO 163a Main Bore TRACERCO 163b Main Bore TRACERCO 163c Side Lateral TRACERCO 163d Side Lateral... ı 3

4 Wellbore (Continued from page 3) Normalized Counts hydrocarbons from two independent reservoir pay zones. They wished to verify that both zones were contributing to overall oil production and that oil was flowing from the toe and centre positions of each lateral. Four unique chemical tracer materials were applied to the outer surface of individual screen sections to be used within the completion at a shore base prior to shipment offshore. The completion design used the same sized screens in both the main bore and lateral. The screens were run in hole by the operator during the positioning of the completion arrangement. The position of tracer materials is shown in Table 1 on page 3. Samples were taken at regular intervals by Tracerco engineers during clean up to the drilling rig and then during first flow from the well back to the main floating production facility through a common subsea line. Results are illustrated in Figure 10. The results showed: Upon first oil flow tracer was first detected from the main bore lateral at position metres 45 minutes later oil from position metres within the main bore was established. During initial clean-up to the rig, zero oil flow was detected from the other lateral. Upon tie back to the process system zero tracer was detected in the first sample due to displacement of existing oil from other wells present in the subsea flow-line. Further confirmation of flow from the main bore upon tie back to the process system. Presence of oil flowing from position metres in the other lateral was detected. Presence of oil flowing from position metres in the other lateral was detected some 30 minutes after position metres. Over time all four positions tagged with tracer showed oil flow. Concentration (ppb) c 163d 163b 163a Time Figure 10 Results of the four unique chemical tracer materials are illustrated in a graph. Upon first oil flow tracer was first detected from the main bore lateral. Wellbore Case Study II A leading oil and gas production company contacted Tracerco to conduct a TRACERCO Diagnostics Wellbore study in order to determine the flow profile of a side track horizontal well. After discussions with the customer, suitable tracers for the application were determined and two chemical tracers TRACERCO 162a and TRACERCO 163a were selected. The quantity of tracer for the project was calculated using information on expected oil production flow rate and duration of the clean up and flow back production test. The two selected chemical tracers were transferred into a suitable solvent and added to a wax at the customer onshore storage facility. Once mixed the material was applied to the inner surface of the pup joints and labeled. (Figure 11) The joints were slowly rotated during application to spread tracer throughout the inner wall. The wax was allowed to cure. The pup joints were dispatched to the offshore drill site and added at specific locations to the wellbore completion string by the customer. The TRACERCO 162a tracer was located at 150 feet from the toe of the well and the TRACERCO 163a tracer positioned half way between the toe and heel. When the clean up and first oil flow back was scheduled two Tracerco engineers were mobilized. A number of 100ml oil samples were collected over the Figure 11 Two selected chemical tracers were transferred into a suitable solvent and applied to the inner surface of the pup joints and labeled. production test time interval. Analysis was carried out. The results of the analysis are shown in Figure 12. The results show that both tracers were detected with two separate and clearly distinct tracer concentration versus time curves with the first tracer (163a) returning within 20 minutes of production start-up and 163a 162a Time (mins) Continued on back page Figure 12 Results indicated that both tracers were detected with two separate and clearly distinct tracer concentrations.... ı 4

5 Subsea Separator (Continued from page 2) Tordis IOR SSBI, the actual subsea profiler units were tested in a full-scale process lab set up, including oil/water emulsion simulator (Figures 5 and 6). The performance tests showed measurement uncertainty at less then 1% for density measurements, for all process medium phases including the oil/water emulsion band. (Figures 7 & 8) A series of other tests were successfully carried out to determine the effect of subsea disturbances, environmental stress screening on the electronics as required by the ISO13628 standard, detector probe inter-changeability and leakage tests on the gamma source and detector subsea housing. Conclusion Three years of fruitful co-operation between FMC Technologies and Tracerco R&D teams has resulted in successful marinization of The TRACERCO Profiler, the de-facto standard within topside separator monitoring, to produce the subsea version of The TRACERCO Profiler. This instrument includes all capabilities of the topside version and has been qualified to ISO13628 and SIL2. Figure 5 Process profile measurement testing Figure 6 Subsea profiler units were tested in a full-scale process lab set up, including oil/water emulsion simulator. Figures 7 & 8 Process profile and process profile trend during subsea Profiler performance test.... ı 5

6 Detect Water Ingress of Jacket Members with TRACERCO Diagnostics FMI Technology Tracerco uses gamma Flooded Member Inspection (FMI) that is a rapid and accurate means of surveying subsea platform jacket members for the presence and degree of water which may indicate structural problems. The main benefit of the technology is its ability to carry out the measurements without the need to clean marine growth from the structure under investigation. The TRACERCO Diagnostics FMI system is operable by attachment and interfacing to a remotely operated vehicle (ROV) or by the use of a diver. A collimated gamma radiation source and sensitive detector unit is mounted on opposite forks of a variable yoke system and positioned across the diameter of the member under inspection. The transmitted radiation intensity is measured and compared to the intensity expected for a dry member based on the particular member s diameter, wall thickness and system calibration. Water inside the subsea section will result in a decrease in the transmitted signal that is easily identifiable. The system provides rapid and accurate measurements of water levels in vertical and angled members and the degree of flooding in horizontal members. The ROV is controlled from topside allowing measurements that can be taken for extended periods of time. The signal from the detector is fed to the surface to an electronic system that records the level of transmitted radiation. The TRACERCO Diagnostics FMI allow operators to focus on areas of the jacket members requiring detailed investigation saving the operator costly subsea inspection time. If you would like to learn more about Flooded Member Inspection please contact a Tracerco representative or visit our website at. Wellbore (Continued from page 4) the second tracer (162a) peaking at 120 minutes. The data confirms that both positions within the wellbore were contributing to overall oil production. The time gap between tracers shows that both zones were contributing to overall production flow rather than all flow originating from the toe of the wellbore. Conclusion The use of the TRACERCO Diagnostics flow profiling technology allows oil flow verification from various positions within a wellbore. The technology has proved to be popular in recent years with major oil companies integrating the technique into their reservoir development plans at an early stage if using highly deviated or multilateral well design. In addition to oil flow verification during first oil flow back Tracerco has recently developed a technology that positions a number of slow release water soluble chemical tracer materials in a completion string. The technology is designed such that tracer is slowly released when water flows across its surface from within the reservoir. When an operator detects a water cut increase from a well, sampling the water and analyzing for the presence of tracer material will allow the operator to determine source of water breakthrough. This information may provide information that can be used to plan a suitable water shut off treatment program within the wellbore. If you would like to learn more about Tracerco s reservoir technologies, please contact a Tracerco representative in your area. North American Headquarters: 4106 New West Drive Pasadena, TX USA Tel: Fax: Toll Free: Field Office Locations: Corpus Christi, TX USA Tel: Newark, DE USA Tel: Merrillville, IN USA Tel: Baton Rouge, LA USA Tel: Concord, CA USA Tel: Paramount, CA USA Tel: Salt Lake City, UT USA Tel: Edmonton, AB, T6E 6A6 CANADA Tel: Sarnia, ON, N7S 5G5 CANADA Tel: Rio de Janerio, RJ, Brasil, CEP Tel: XM0345/0/0

7 NO POSTAGE NECESSARY IF MAILED IN THE UNITED STATES NO POSTAGE NECESSARY IF MAILED IN THE UNITED STATES BUSINESS REPLY MAIL FIRST-CLASS MAIL PERMIT NO 9 LA PORTE TX POSTAGE WILL BE PAID BY ADDRESSEE BUSINESS REPLY MAIL FIRST-CLASS MAIL PERMIT NO 9 LA PORTE TX POSTAGE WILL BE PAID BY ADDRESSEE TRACERCO P.O. BOX 641 LAPORTE TX USA TRACERCO P.O. BOX 641 LAPORTE TX USA Please send me additional information on Tracerco s offshore/reservoir applications: Tracerco would like to update our database for Please complete the information below to register for copies of the Tracerco News. The TRACERCO Profiler TRACERCO Mud monitor TRACERCO SlugMonitor TRACERCO Diagnostics Separator study TRACERCO Diagnostics FMI TRACERCO Diagnostics Pipeline assurance TRACERCO Diagnostics Flow study TRACERCO Diagnostics Interwell study TRACERCO Diagnostics Wellbore study TRACERCO Diagnostics Flow profile TRACERCO Diagnostics SlugMonitor Specialist Measurement Instruments I would would not like to continue receiving future issues of Tracerco News. I would like to schedule an on-site presentation. I am interested in additional information on the following: The TRACERCO Profiler TRACERCO Mud monitor TRACERCO SlugMonitor TRACERCO Diagnostics Separator study TRACERCO Diagnostics FMI TRACERCO Diagnostics Pipeline assurance TRACERCO Diagnostics Flow study TRACERCO Diagnostics Interwell study TRACERCO Diagnostics Wellbore study TRACERCO Diagnostics Flow profile TRACERCO Diagnostics SlugMonitor Specialist Measurement Instruments Name: Name: Job Title: Job Title: Company Name: Company Name: Address: Address: City: State: Zip Code: City: State: Zip Code: Phone: Phone: Vol 1 Ed 1 Vol 1 Ed 1