Complex oil displacing method suitable for large well spacing condition of offshore oil field

Abstract

The present invention discloses a complex oil displacing method suitable for the large well spacing condition of the offshore field. The saturation relationship curve between the capillary number and the residual oil is produced through the oil displacing experiment for confirming optimization range of the capillary number, and furthermore the oil displacing elements are optimized according to the optimization range. In the process of optimizing the oil displaying elements, the fixed well spacing and the liquid injection speed are confirmed according to the characteristic of the offshore oil field, the underground seepage speed of the part which easily generates the driving state conversion is confirmed with an oil accumulation analyzing method. Then the reference area of the underground working viscosity is generated according to the field construction state. The interfacial tension and the underground working viscosity of the oil displacing system are optimized by the safety factor and the effect coefficient. Finally at the state that the well spacing and the liquid injection speed are confirmed, the complex oil displacing oil production is executed. The complex oil displacing method of the invention can combine the specific construction state for limiting the capillary number to an optimized range for guaranteeing the stability of the complex oil displacing method and a relatively high recovery factor increasing amplitude.

Description

technical field [0001] The invention relates to a tertiary oil recovery method in an oil field, in particular to a compound flooding method suitable for offshore oil fields with large well spacing. Background technique [0002] Composite oil flooding technology is an important new technology in the field of oilfield tertiary oil recovery technology. Its research and application are at different stages, and most countries and oilfields are in the stage of indoor experimental research and field test. In the middle of the last century, T.F.Moore, J.J.Taber, W.R.Foster and others successively proposed the hydrodynamic force and the capillary retention force in order to study and describe the "relationship between the captured residual oil flowing into the flow and the capillary retention force" during the oil displacement process. The concept of the ratio of academic force to capillary force is called the capillary number N C (N C = hydrodynamic force / capillary force, that is,...

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Problems solved by technology

In the application of compound flooding technology, the field test results of Daqing Oilfield show that the recovery rate of ASP flooding is about 20%. Due to the high concentration of chemical agents in the system composition and high requirements for surfactants, the investment is relatively high. Large, the economic indicators cannot meet the requirements, and there are many difficulties in industrial production; in addition, a relatively high concentration of strong alkali is used to ensure the ultra-low interfacial tension of the system. Very serious damage to equipment

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