In-Situ CO₂ Generation Technology in Bohai P Oilfield

In order to solve the problem of low water flooding development efficiency caused by strong reservoir heterogeneity, high water injection intensity, injected water influx and ineffective circulation in the Bohai P Oilfield, a study of in-situ CO₂ generation technology was carried out. Firstly, the optimal gas generation system was selected by evaluating gas generation efficiency. Then, the foaming agent and blocking agent were screened by the Waring-Blender method and sandpack column flow experiment. Laboratory test results showed that gas generation efficiency could reach 96.2% when the gas system was blowing agent A + gas release agent D. The optimal foaming agent system was 0.2% foaming agent 2 + 0.1% foaming agent 5. The foaming volume was 740 mL and the half-life of dissolve-out liquid could be maintained for 219 seconds. When blocking agent 1 was added in the foaming system, the plugging rate could be maintained above 90% in the sandpack column with a permeability of 2 000-10 000 mD. The in-situ CO₂ generation technology had been used in 15 injector producer pairs of the Bohai P Oilfield, resulting in the enhancement of accumulative oil recovery of 33 413 m³ by injecting 69 986 m³ of CO₂ in total, with the effective rate reaching 100% and effective period up to 5 months, which indicated that in-situ CO₂ generation technology had good applicability in Bohai P Oilfield and dissolves the problems existing in the water flood development of this field.