The Thompson Creek Recluse reservoir is located in Section 10 of Township 57N and Range 67W in Crook County northeastern Wyoming.Thompson Creek produces from the Recluse (Muddy) sand and is a shallow high quality sandstone reservoir with average permeability of 940 mD.The reservoir has 24.8% porosity with approximately 31,500 Mbbls oil at a depth of 1,600 ft.The crude oil is a 19o API gravity oil with a viscosity range of 250 to 650 cp going south to north in the field.Initial production from the field was in 1987 and by 2002 there were 16 wells, including 4 horizontal producing wells when the field was acquired by Dakota Gas.Limited water injection into two wells began in August 2001, which by October 2003 was only about 300 Mbbls cumulative injection, whereas cumulative oil production was 710 Mbbls and oil rates were about 90 bbl/day.By December 2008, well count has increased to 47 wells consisting of 21 injection wells and 36 production wells. The figure to the left shows the net pay sand thickness.
Radial coreflood studies performed by SURTEK showed waterflood recoveries averaged 44% OOIP.These high recoveries are a reflection of the quality of the Thompson Creek Field in spite of the unfavorable mobility ratio due to oil viscosity ranging from 250 cp near the gas-oil contact to over 650 cp near the water-oil contact.Radial coreflood studies showed that an average of 70% more oil could be recovered by AP flooding than by waterflooding.The figure to the right shows typical radial coreflood response.
Alkaline-Polymer injection began in February 2004 with 0.35% Na2CO3 + 1600 mg/L Flopaam 3630 being injected at 1,800 bbl/day by May 2004.Response was very rapid, with oil production rates climbing to over 400 bbl/day by the end of May 2004, and greater than 525 bbl/day by May 2006.The figure to the left depicts the oil and water production as well as the oil cut for Thompson Creek.A defined response is observed due to chemical injection.Additional wells, both injection and production, were drilled for the chemical flood implementation.As a result, the response seen is due to chemical injection as well as additional wells.
Numerical simulation waterflood forecast to the year 2017 showed a cumulative oil recovery of 5,305 MSTBO (16.7% OOIP) at a final oil cut of 2.9%.This recovery required injection of 60,593 Mbbls of water.Oil cuts decrease from 99% to 36% in less than 2 years and dropped to 27.5% at the time of peak oil production rate of 2,800 bbl/day.About 40% of the waterflood operations occur at watercuts of 90% or greater, as a consequence of the very unfavorable mobility ratio.AP flooding forecasts though had much greater recovery efficiency.AP flood incremental oil recovery prediction was 4,770 Mbbls of oil more than the waterflood for a total of 10,075 Mbbls or 32.0% OOIP.Total injection was 32,095 Mbbls of fluid.Oil rates of over 3,000 bbl/day sustained for over 7 years for AP flood with peak production of over 4,000 bbls/day were forecasted.The figure to the right shows the numerical simulation forecasts that illustrate the greater oil recovery with alkaline-polymer flooding over waterflooding with one-third the volume of fluid injected.
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