FIDDLER CREEK POLYMER AUGMENTATION PROJECT

Johnson, Lyle A., Jr.

National Energy Technology Laboratory (U.S.)

关键词: Petroleum Residues;    02 Petroleum;    Stabilization;    Polymers;    Waterflooding;   

DOI  :  10.2172/789610
RP-ID  :  FC26-98FT40323--05
RP-ID  :  FC26-98FT40323
RP-ID  :  789610

美国|英语

来源: UNT Digital Library

【 摘 要 】

The Fiddler Creek field is in Weston County, Wyoming, and was discovered in 1948. Secondary waterflooding recovery was started in 1955 and terminated in the mid-1980s with a fieldwide recovery of approximately 40%. The West Fiddler Creek Unit, the focus of this project, had a lower recovery and therefore has the most remaining oil. Before the project this unit was producing approximately 85 bbl of oil per day from 20 pumping wells and 17 swab wells. The recovery process planned for this project involved adapting two independent processes, the injection of polymer as a channel blocker or as a deep-penetrating permeability modifier, and the stabilization of clays and reduction of the residual oil saturation in the near-wellbore area around the injection wells. Clay stabilization was not conducted because long-term fresh water injection had not severely reduced the injectivity. It was determined that future polymer injection would not be affected by the clay. For the project, two adjoining project patterns were selected on the basis of prior reservoir studies and current well availability and production. The primary injection well of Pattern 1 was treated with a small batch of MARCIT gel to create channel blocking. The long-term test was designed for three phases: (1) 77 days of injection of a 300-mg/l cationic polyacrylamide, (2) 15 days of injection of a 300-mg/l anionic polymer to ensure injectivity of the polymer, and (3) 369 days of injection of the 300-mg/l anionic polymer and a 30:1 mix of the crosslinker. Phases 1 and 2 were conducted as planned. Phase 3 was started in late March 1999 and terminated in May 2001. In this phase, a crosslinker was added with the anionic polymer. Total injection for Phase 3 was 709,064 bbl. To maintain the desired injection rate, the injection pressure was slowly increased from 1,400 psig to 2,100 psig. Early in the application of the polymer, it appeared that the sweep improvement program was having a positive effect on Pattern 1 with lesser effects in Pattern 2. These early observations did not continue to develop. The oil production for both patterns remained fairly constant to the rates established by the restart of waterflooding. The water production declined but stabilized in both patterns. The stabilization of the oil at prepolymer rates and water production at the lower rates can be attributed to the polymer injection, but the effect was not as great as originally predicted. The sweep improvement for the patterns appeared to be negatively impacted by extended shutdowns in the injection and production systems. Such problems as those experienced in this project can be expected when long-term polymer injection is started in old waterflood fields. To prevent these problems, new injection and production tubulars and pumps would be required at a cost prohibitive to the present, independent operators. Unless the future results from the continued waterflood show positive effects of the long-term polymer injection, it appears that the batch-type polymer treatment may have more promise than the long-term treatment and should be more cost effective.