Study On The Technology Of Increasing Injection Of Qi - Gu Reservoir In

The field data shows Che2Qiguzu is a medium porosity, low permeability reservoir with strong water sensitivity. During the long time for waterflood development, the injection pressure becomes higher and higher, and the field has taken many reservoir stimulations to deal with it. But now, the injection pressure reaches and keeps at a high level, the effectiveness of stimulation becomes poorer and poorer. For water absorption capacity of the reservoir getting worse, it hardly meets the requirement of injection.In view of this situation, through combining statistical analysis of field data with laboratory experiments, this paper studies on the reason of reservoir damage, the reason why the effects of acidification becoming poorer and poorer, and proposes a techniques to solve these problems. These details are as the follows:(1) By the use of X-ray diffraction, fluid composition analysis, core flowing tests and other means, this paper analysises the reservoir rock properties, porosity, permeability, and characteristics of the reservoir fluid. The results reveal the reservoir is strong water and speed sensitivity, moderate-strong volume flow sensitivity.(2) In the mean of analysising the composition of the injected water ions and quality, comparing water injection speed with critical velocity, the reason of reservoir damage is scaling,excessive amount of solid particles,daily water injection rate exceeding the critical velocity, and swelling clay minerals migration.(3) Through stating the various water injection wells’dynamic history, calculating and comparing the change of water absorption index when there were any stimulations.And combining with experements, they prove acidification has certain limitations:the radius of plugging is small, it is difficult to remove the deep reservoir damage, and the flow path for the long-term acid will get a certain degree of damage.(4) The reservoir protection during injection includes water sac ling pretreatment on the ground, filtering by efficient modified fiber ball, controling water injection, and alternating injecting shrink swelling agent and anti-swelling agent.(5) For fracturing, by laboratory experiments, this paper selects fracturing fluid and proppant type. By numerical simulation method, I determine the optimal fracture half-length90m, conductivity40D·cm, and give the corresponding hydraulic fracturing design:284m3total fluid volume,31%pre-liquid ratio,35.8%average sand ratio.The studying methods and results in this paper have a certain significance to improve the amount of water injected for other similar sandstone reservoir.