Deep profile adjustment and oil displacement sweep control technique for abnormally high temperature and high salinity reservoirs

Abstract

Abstract: To improve water flooding sweeping efficiency and oil displacement efficiency in reservoirs with abnormally high temperature and high salinity during late development stage, taking Gasikule E31 reservoir as the research object, lab study and field test of sweep control technique (SCT) were conducted. Performance evaluation and field test results of soft microgel (SMG) agent show that: SCT has good thermal stability in the target reservoir and an effective period of 100−120 d in the field test, and the success rate of SCT can be greatly increased by adjusting particle size and concentration of the gel. Unlike polymer flooding or polymer-gel flooding which improves oil recovery by enhancing sweep efficiency, SCT can improve oil displacement and water sweep efficiency, and its displacement mechanisms have been confirmed by the lab experiment and field test. The SCT has been applied in six well groups in the target reservoir, resulting in a cumulative oil increment of 1.03×104 tons, water production drop of 4.79×104 m3, and an input-output ratio of 1:2.09. But when international oil price is low, SCT project may have high failure risk in application to reservoirs with abnormally high temperature and high salinity. Key words: high temperature high salinity reservoir, soft microgel, sweep control technology, deep profile control, oil displacement mechanism, economic benefit