The re⁃injection block containing the sewage in the Xing 13 area is affected by the residual polymer,which leads to a decrease in the water absorption effect of the block and affects the development effect of the oil field. Therefore,the formulation and supporting process parameters of the depressurization and infusion injection of the sewage⁃containing block were studied.Firstly,the total water quality of injected water was analyzed; Then the petroleum sulfonate was used as the basic agent to screen the compounding agent and additives by measuring the interfacial tension;After the performance evaluation of the system, the indoor core flooding experiment was carried out to optimize the injection parameter.The results show that the optimal formulation of the anti⁃hypertensive surfactant is(mass fraction):0.7% petroleum sulfonate+2.0% HABS+0.5% absolute ethanol+1.0% NaCl,and the interfacial tension between the crude oil and the interfacial tension is 6×10-3 mN/m.In the core flooding experiment,the optimal injection rate is 0.15 mL/min,the optimal injection volume is 1 PV,and the optimal slug combination is 0.5 PV+0.3 PV+0.2 PV. Under different permeability conditions,the pressure rate is more than 24%.

In order to study the interlayer interference mechanism of water drive reservoir, the development plan of multi⁃layer co⁃production is developed. The core hole and permeability data of Gaotaizi core in the western Daqing central region are statistically analyzed, and the four⁃pipe parallel constant pressure displacement experiment is carried out with artificial cores with different permeability. The effects of injection and production pressure difference and permeability grade difference on recovery and water cut are studied. It is found that there is a reasonable injection⁃production pressure difference in core co⁃production with different permeability. The larger the permeability gradient is, the smaller the overall recovery is. The influence rule of permeability difference on interlayer disturbance is clarified from the mechanism, which provides theoretical basis for subdivision adjustment and water quantity adjustment.

In view of the increasing water content in China's oil fields, foam has good pugging performance and flow redirection effect, and has broad application prospects. In this paper, the sealing characteristics of bubble redirection effect was studied, the fluid flow was investigated under the condition of different seal characteristics of foam, and effect of flow redirection and enhancing oil recovery was examined. The results show that the foam has good plugging performance, and can be effectively blocked under suitable conditions. The higher the back pressure, gas liquid ratio and core permeability are, the lower the injection speed is, the bigger the resistance factor and residual resistance factor of the foam are, the greater the plugging is. For non-homogeneous reservoirs with a permeability differential of 5.56, foam has effect of flow redirection and can plug the high permeability layer in core selectively. The subsequent injection of water into the low permeability layer will drive out the residual oil, and the bubble drive will increase the recovery rate by 28%.

Aiming at conventional heavy oil reservoir, 3-D dimensional cross-section model was employed to study thermal water flooding or water-steam alternative injection after steam flooding in anti-rhythm reservoir, positive rhythm reservoir and composite rhythm reservoir. The results show that steam trended to flow on the top of reservoir due to over lap of injection steam. Steam channeling is more easily generated in anti-rhythm reservoir than in positive rhythm reservoir. Thermal water flooding and water-steam alternative injection after steam flooding could carry remaining heat to migrate into the bottom of reservoir, so amount of heavy oil in reservoir can be recovered. The recovery efficiency of water-steam alternative injection is obviously higher than thermal water flooding and water cut decreased largely during water-steam alternative injection.

Natural gas hydrate，which deposits on the ocean floor or in permafrost regions in vast quantities, is a potential future energy resource. The method by depressurization is known to be adopted for large scale exploitation natural gas hydrates. The heat transfer boundary can affect overly hydrate dissociation rate. Investigated these control mechanisms, built one two-dimensional model, and analyzed the change of temperature,pressure,hydrate saturation and cumulative gas produced under the influences of different heat transfer boundary conditions. The calculation results show that natural gas hydrates exploited by depressurization need heat transferred from surroundings. The amount of gas produced at adiabatic condition is only 1/36 to that of gas produced in complete decomposition. With higher temperature at boundary, hydrate decomposes more rapidly, decomposition rate at boundary temperature 277.45 K is 2.5 times as much as that at 275.45 K, and gas generated rate is greater, but the magnitude of heat makes a minor effect on cumulative gas produced.