| The thickness of Chang8reservoir of Zhenyuan oilfield Block53is about70to90m, and the thickness of Chang81reservoir that is this paper’s research subject is about40m. Chang81reservoir in research region is subdivide into Chang811Chang812, and Chang813according sedimentation cycle theory and the method such as marker bed control, deposition thickness. Reservoir properties of Chang8sand layer is poor, low porosity and extremely low permeable reservoir. In the light of statistical analysis of the measured data, the porosity of the Chang8reservoir range from1.1%to18.76%, average porosity9.75%; Permeability distribution between0.004410-3μm2and27.35×10-3μm2, average permeability1.34×10-3μm2. Reservoir properties of Chang8sand layer is poor, low porosity and extremely low Permeability, the porosity and permeability vary greatly, with high reservoir heterogeneity.Since Chang8reservoir of Zhenyuan oilfield Block53put into operation in2003, its development process can be roughly divided into three stages:Construction production stage (2003.10～2007.6), Stable yield stage (2007.7～2008.10), production descending stage (2008.11～now). Currently, Chang8reservoir of Zhenyuan oilfield Block53has opening oil well79, water wells41, daily liquid production220t, daily oil production174t, comprehensive water cut18.3%, average dynamic liquid level1397m, daily oil production for single well is2.2t; monthly injection-production ratio3.0, cumulative injection-production ratio1.93, daily water injection849m3, daily water injection for single well is20.7m3.After a long period of development, Chang8reservoir of Zhenyuan oilfield Block53has to address the following increasingly prominent issues:(1) With developed micro fractures and injected water promoted along the principal stress directional well lead to shorter responding time of waterflooding for principal stress directional well, more flooding, low degree of recovery, reduced lateral wells effective, lower production;(2) The effect of adjustment on oil wells is not obvious, big difficulty to control flooding wells, influenced by physical properties measures are not effective, Stable yield is difficult, especially for oil wells at south work area.In view of the problems of Chang8reservoir exposed during production such as low natural productivity, fast decreasing rate, shorter responding time of waterflooding led by fractures for principal stress directional well; higher injection pressure, rising slowly, little potential for increasing injection, reservoir developed in poor condition. So, basic research is needed in reservoir description Chang8reservoir, combined with research and analysis of reservoir engineering, reservoir simulation study of the use of technology formulate a reasonable policy development technology, to solve present problems facing the reservoir, while providing a reliable basis for decision making measures tapping to resolve present problems.From what have discussed above, the conclusion can be drawn:1. Daily production more than five tons of oil wells was reduced from24early to5, according to the analysis of single well production characteristics, with proportion cut down from22.8%to4.8%; Daily production less than1tons of oil wells was increased from55early to84, with proportion rise up from52.4%to80%; Daily production from3tons and5tons was decreased from26early to16, with proportion fell down from24.8%to15.2%, all those fully shows that well productivity diminish faster. Forecasted by empirical formula, water drive characteristic curves and decrement formula method recovery ratio of Zhenyuan oilfield Block53is19.1%and recoverable reserves117.43×104t. The production decline rule for Zhenyuan oilfield Block53is matched by exponential decline curve.2. In this research region, sudden water influx wells result from fractures, slowly water rising wells because of micro fractures, According to statistical analysis on the water breakthrough situation. In view of the style of water breakthrough combined with study of crack distribution, sudden water influx wells result from fractures and water promoted along well array direction.3. Currently, water flooding effect becomes better, according to the study on water storage rate and water flooding index, mainly due to principal stress directional well with sudden water influx conversed to water injection well, gradually effective of lateral wells get better gradually.4. On the base of reservoir engineering analysis, there are some problems facing Zhenyuan oilfield Block53:low natural production, fast decreasing rate, cracks cause shorter responding time of waterflooding for principal stress directional well, sudden water influx; Higher injection pressure, slowly rising, increasing injection has little potential. This paper propose a few development proposal:principal stress directional well with water influx turn into water injection well and meantime the wells arranged in row; According to the analysis of water injection profile, geology and production situation, the well Zhen82-53should adopt In-depth Profile Modification; Try cycle injection test; Try new techniques to improve the effect of crack injection.5. On the basis of well pattern, well spacing, injection-production ratio, liquid production rate and bottomhole pressure,26sets of development technology policy programs have been designed to make prediction and optimal decision. The research conclusions:Anti-nine well pattern has better development effect; Well Spacing range from400to480meters is more suitable for the development of the reservoir; Recommended fluid production rate of1.26%, bottomhole flowing pressure not less than5Mpa, injection-production ratio2.9; As to the wells waited for transferred to water injection, it’s better to do that when the water content up to60%. |
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