Deep-hole, High-temperature Submersible Pumping

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Abstract There were 96 electric submersible pumps operating in the harsh environment of the 230 °F (110 °C) Beaverhill Lake formation of the South Swon Hills Unit at the end of 1977. Here 95% of the pumps are installed in 4-1/2-in. (114-mm) and 5-1/2-in. (140-mm) casing at an average depth of 8,000 ft (2,438 mi. A miscible flood covering half of the Unit contributes to an average producing GOR of 1,100scf/STB (195) and a number of wells produce with GOR's in excess of 2,000 scf/STB (354). These conditions of close tolerances, high temperature and high GOR have resulted in many operational problems. A number of procedures which have been developed to improve pump performance are presented. Introduction The Swan Hills oil field is located 140 miles (225 km) northwest of Edmonton, Alberta (Fig. 1). The Amoco-operated South Swan Hills Unit (Fig. 2) was formed in 1962, with 193 wells on 160-acre (64.8-hectare) spacing. Production is from the 230 °F (110 °C) Swan Hills formation of the Beaverhill Lake group, a limestone reef complex. Waterflooding commenced in 1963, and was expanded from 5 to 22 injection wells by 1972. In 1973, a secondary recovery miscible flood project was initiated in the central portion of the field. This project consists of alternate injection of enriched gas solvent and water (1973-1978), dry gas (1979-1987) and then water (198B-200B). The first electric submersible pump was run in January, 1971. By the end of 1977 there were 96 submersible pump installations. The Unit was producing approximately 60,000 BOPD (9,540 m3/day) and 60,000 BWPD (9,540 m3/day) at this time. Production History Production performance for the miscible flood area, since the first submersible pump was installed in 1971, is detailed in Figure 3. There are 95 producing wells in this area. By the end of 1977, 63 (66%) were submersibly pumped, producing 80% of the oil. Twelve of the producers were flowing, and the remainder were beam pumped. The average GOR's has risen from the solution GOR of about 750 scf/STB (133) to as high as 1,330 scf/STB (229) in 1976. Miscible fluid breakthrough in several wells has resulted in periodic GOR's as high as 10,000 scf/STB (1,772). The combination of small production casing I.D.'s and high GOR's has caused severe submersible pump operating problems. Figure 4 is a production plot for the west waterflood area. There are 52 producers in this area. By the end of 1977, 33 (63%) were submersibly pumped, producing 85% of the oil. The remaining producers were beam pumped. No submersible pumps have been installed in the east waterflood area of the South Swan Hills Unit- This area is located off the main reef build-up and total production averages less than 200 BOPD (32 m3/d). Submersible Pump Equipment Configuration The downhole submersible pumping equipment (Fig. 5) consists of the pump assembly (centrifugal pump, gas separator, motor protector and motor), No. 4 lead sheathed flat cable to the top of the pump, and high-temperature No.6 flat cable to the pothead connection at the motor.