MARTEN HILLS GAS WELL DEWATERING

J. RILEY B. HALE

this article begins on the next page FFJCPT79-01-07 PRODUCTION Marten Hills gas well dewatering J. RILEY and B. HALE Amoco Canada Petroleum Company Ltd. Calgary, Alberta ABSTRACT Marten Hills Gas Unit No. I has been on stream since 1969, with production from the Wabiskaw sand and Wabamun D- I carbonate. Water influx from the underlying Wabamun D-] aquifer became a significant problem in 1975. Production declined substantially in a large number of wells due to high well bore fluid levels and highflowing gradients in combination with low reservoir pressure. Several methods of dewatering the wells were evaluated, with the beampumping unit proving most effective. Currently, 18 of the 38 wells tied into the gas gathering system have beam pumping units installed. This paper discusses the history behind the selection Of bottom-hole pumps, past and present operating problems associated with this application, and current refinements to improve run lives. Production History Marten Hills Gas Unit No. I is located approximately 145 miles (233 km) northwest of Edmonton. It is a shallow low- pressure gas field with production from the Wabiskaw sand and Wabamun D-1 carbonate. After coming on stream in late 1969,the field produced minimal amounts of water. However, by 1972 isolated in- stances of water production resulted in at least one well being throttled back to lower its water production. At the time, there were no water handling facilities in the field except lease flare pits and an evaporation pond. These pits were subject to strict quotas regarding quantity of produced water that could be handled each month. By early 1975, water influx from the ac- tive Wabamun D-1 acquifer became a significant problem. Figure I is a production graph for the Marten Hills Gas Unit No. 1. The buildup ofwater in wellbores and surface towline created backpressure which severely reduced well productivity. In some cases, the buildup was enough to cause wells to cease flowing. Several methods of handling and controlling the water were evaluated before a consistent field-wide method of dewatering was determined. The Marten Hills Field consists of two main gas-bearing for- mations, shown schematically in Figure 2. The lower forma- tion (Wabamun) is a carbonate deposit of Devonian age. It varies from a dense to vuggy limestone and in the eastern por- _ 140- 3 LL , 20 I00 so 0 cc A. 60 -- co 40 -- 20 -- 0 t 1400 - 1200 - 1000 - 0 c IL cc &U 200 - 0 1971 1972 19974 1976 1"7 1 1 1 1973 1 11 NOTE: I BBL - 0.164 m3 I MMCF - 20= M3 FIGURE 1. Momen Hilb production. 86 The Journal of Canadian Petroleum