| Over recent years in oil/gas field development, with being continually recognized reservoir in development period all has characteristics like rapidly increasing water cut and low degree of reserve recovery. Worldwide geologic research of oil field development advances rapidly. Multidisciplinary intersection, new conception, new technology and new method followed each other in rapid succession, which indicates the vital influence of geologic research in oil field development to improving oil field’s development level. With more and more deep study into oil field development, it seems that base of oil field development is good or bad correspondence of single sand body.Beisantai oilfield lies on100kilometers to the east of Urumqi. Tectonic location is in south central Zhangyibei uplift of east Junggar Basin, a rising north slope of Beisantai. In September of1985, bei12well first yielded oil in a low production (with a choke size of4mm and a daily oil production of1.9t). In June of next year, bei16well yielded oil (with a choke size of4mm and a daily oil production of13.3t and a daily gas production735m3). At present reservoir of Wutonggou Group in bei16well faulted nose, bei31well faulted nose, bei75well faulted block and bei20well faulted blocks is put into production. Since being put into development from1989-1990, Beisantai oilfield has got a good development effect. With the deepening of recovery degree, it reaches a production decline period in1997, in which water cut ascending becomes rapidly and natural decline becomes greater. Stabilized degree of production declines year by year and rate maintenance situation is severe. At present Beisantai oilfield is in medium and high water cut stage withinjection/production contradiction and difficulty in rate maintenance. After multistage reservoir description and geological study of Beisantai oilfield in2003-2007, we got new recognition of reservoir structural form, faulted distribution, reservoir distribution, difference of lithologic and physical property in plane. On that basis it is necessary to study residual oil distribution and adjusting exploitation measures to determine comprehensive adjusting case. According to the geological characteristics and develop dynamic of the reservoir,the microscopic heterogeneity is studied by water-flooding experiments, oil-water relative permeability curves and capillary curves; Comprehensive evaluation of the macroscopic heterogeneity is evaluated comprehensively by statistical method, log-normal curve method and the Lorenz curve method. It is found by the research that the northern santai reservoir is a weak hydrophobic and intermediate wet reservoir with strong speed sensitivity, water sensitivity, injection sensitivity and great anisotropy in the three main areas. Fluid mobility ratio in the three main areas calculated by relative permeability curves, distributary curves and viscosity is above1, which shows great possibility of viscous fingering, statistics of formation pressure in the areas of high pressure (Pr>0.95Pi) and low pressure (Pr<0.7Pi) are gathered from the data in2008-2010. it is found that the pressure is higher in high water content area and the pressure is lower in low water content area. The formation of the high pressure and low pressure are analyzed. The poor exploration extant in the three main areas in the northern santai reservoir is caused by unstable barrier, fracturing, fill layer, etc. the most effective measures are provided for the next project of tapping potential.Part of numerical reservoir simulation, it crude into numerical reservoir simulation model based on fine geological model. Then do history matching for the production wells of three main blocks of BeiSantai oil field through the application of ECLIPSE software. We arranged potential wells in the rich region of residual oil and predicted the program based on the history matching in good agreement, Combined with the current development situation of BeiSantai oil field, to extract, reperforating, change layer or add the adjustment well in the remaining oil-rich region, then do the program forecast. All prediction programs which simulative operation of10years have achieved a good effect of increasing oil production compare to programs0.Programme5of North16wells Areas is like this:first screening on the better effective of wells which have been reperforating and extract,thenl drilling new wells. Programme5increasing oil capacity of374,680tons compare to programme0, the recovery increased by4.13percentage. It can be a preferred program in North16well area in the future.Programme4of North31wells area is drilling of new wells based on reperforating, and increasing oil capacity of198,080tons compare to programme0, slightly less than programme3, it due to the number of wells of programme3which have been taken extract measures up to18, while drilling of new wells of program4is in a relatively small number, programme5is to extract based on programme4and increasing oil capacity of257,770tons,enhancing oil recovery by3.67percentage points compared with program0. Programme5have achieved the best results which can be an important direction for tapping the potential in North31wells area.Scheme5of North75wells Areas has peak oil production, maximum recovery and highest water cut of all the programs. The investment cost of drilling a new well is much larger than reperforating, water control and other regular measures of increase of oil, once deployed, well sites improper can easily result in low productivity of new well, resulting in great economic losses. Therefore, in the adjustment process of the development plan, the deployment of the new wells should be cautious. To evaluate the feasibility on drilling new wells should combined with economic efficiency. Program5increasing oil capacity of75,420tons and oil recovery increased by3.195percentage points compare to programme0, visibly, the effect of increasing oil by reperforating, extracting and drilling new wells in the North75well area is significantly. |
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