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In a new subsurface evaluation, Jersey Oil & Gas, a British-independent North Sea-focused upstream oil and gas company, has uncovered a new prospect, named Wengen, to complement its Verbier Deep, Cortina NE, and Zermatt drill-ready prospects. The four are estimated to host some 222 million bbl of P50 prospective resources, all in the immediate vicinity of Jersey's planned GBA production facility. The consolidated Greater Buchan venture comprises Buchan field (80 million bbl), Verbier (c25 million bbl), J2 (c20 million), and Glenn (14 million). The new prospect, located in License P2170, is directly west of the Tweedsmuir field and should host some 62 million bbl of potential resources (P50), with the probabilistic range set at 31 million bbl at P90 (higher confidence) and 162 million for P10 (lower confidence). Probability of geological success is 22% for the prospect.
Prospect evaluation starts with laboratory studies of various enhanced oil recovery (EOR) processes. Results of EOR floods in waterflooded cores processes. Results of EOR floods in waterflooded cores are given for caustic, dilute surfactant, micellar solution flooding, and polymer augmented waterflooding. In this work, partially hydrolyzed polyacrylamide (PHPA) was used as the mobility control agent. A pilot scale PHPA manufacturing plant, built in the pilot scale PHPA manufacturing plant, built in the field, supplied polymer for both lab and field testing. Results are presented from a polymer injectivity test at a water injection well. The injection well completion and surface facilities used in the test are described. Water to polymer injectivity is compared as a function of polymer concentration. Pressure data are used to establish the effect of polymer on solution mobility in the reservoir. Computer modeling was also used to match the lab and field results and to predict field oil recoveries for making economic calculations. Economic studies are the final step in the prospect evaluation procedures. Economic results using the same example field project for two different EOR methods are presented.
After waterflooding, significant volumes of oil remain in reservoirs as a potential resource for enhanced oil recovery (EOR). Procedures are presented for evaluating a reservoir as a chemical EOR prospect.
Prospect evaluation starts with displacing fluid system design and laboratory core flooding using actual reservoir rock and fluids. Oil recovery results after waterflooding are used to give an indication of the EOR potential of the field. Results are presented for the various chemical EOR processes, presented for the various chemical EOR processes, including micellar solution, dilute surfactant, caustic and polymer augmented waterflooding. Next, a computer modeling technique is described that uses both laboratory and field results to generate a field recovery curve for making economic calculations.
Of the chemical processes we evaluated, all but caustic normally use polymer. Marathon's partially hydrolyzed polyacrylamide polymer (PHPA) was used as a mobility control agent in this work. Polymer used both in laboratory and field testing was field manufactured.
Field testing to determine polymer injectivity is the next evaluation step. Definitive polymer field injectivities can not be obtained in the laboratory. Most chemical EOR processes require large pore volumes of polymer solution. The key to project life and economics depends to a large degree on the polymer injection rate. Therefore, a significant part of our evaluation procedures is the field injectivity test. Results are presented of a polymer injectivity test using one well in a prospective reservoir. Ideally, the polymer injectivity testing includes several wells covering a range of water injection rates. Techniques used to perform the field test are described, and data presented. presented. Finally, economic considerations are used in our prospect evaluation procedures. As an example, prospect evaluation procedures. As an example, economic calculations are presented for surfactant/ polymer (micellar/polymer) and polymer flooding the polymer (micellar/polymer) and polymer flooding the same reservoir. The results illustrate the role economics play in chemical EOR prospect evaluation.
Laboratory core flooding is an integral part of chemical prospect evaluation. Figure 1 shows a schematic drawing of the radial core used in the flood Details of using this disk flooding technique have been described elsewhere. Radial cores provide a larger volume of rock than linear core plugs. The resultant larger fluid volumes provide more accuracy in interpreting laboratory experiments. From pressure drop data, the effect of attenuating frontal velocity on mobility can be measured. Also, the radial disks provide a configuration such that some rock provide a configuration such that some rock heterogeneities can affect the floods.
Reservoir rock with a diameter of between 4 and 6 inches is used in the chemical EOR floods.