A Research Of Finely Injecting Water To WX3Reservoir

After decades of waterflooding processes, the old oil fields in the world have already went into the stages of high water-cut and high recovery percentage of reserves. Most oil fields in china are at the latter stage of high water-cut or at the stage of ultrahigh water cut, having the water-cut up to80%. For high water-cut reservoirs, about more than70%of the remaining oil will be recovered at the stages with water-cut higher than80%, thus, this will lead to more and more difficult recovery processes. Such abundant remaining oil is the rich foundation of improving reserve and the important basis for EOR. However, looking for such remaining oil and recovering them economically have been a very important and under-resolved issue for our high water-cut oil fields which are at the new exploitation stage. It has been proved in the reservoir exploration and development that the key of success is up to the extent of reservoir recognition. Reservoirs in China are complex especially in the mid and late period of reservoir development, most of which are in their production declin stage with high water cut. The difference, shield effect, sensitivity, unstability of the heterogeneous formations as well as the imperfect of well patterns will lead to the heterogeneity of flowing of fluid in all directions, the sporadic difference of displacement extent and the sporadic distribution of residual oil. Beside, as the result of long period?s flowing of water, there will be a series of physical, chemical, mechanical changes in reservoirs and fluid characteristics. All the above factors will cause more serious heterogeneity in reservoirs. So in order to explore the distribution of residual oil more exactly, accurately and measurably, It is necessary to carry out reservoir description. Based on exact reservoir contradistinction, this p’iper provide detailed research and its conclusions on micro tectonic research technique, subdivision micro sedimentary facies, flowing units study, physical property and fluid distribution ways, reservoir numerical simulation technique.WX3reservoir has been exploited by waterflood for18years since1994. At present, the block has entered high water cut development period. During the period, the block development has adopted various technology, such as well network Infilling adjustment, rolling and increasing storage, adjustment of injection structure, to enlarge the production of pressure mining, secondary development, etc. The block obtained certain development effect by these adjustment and management technology. However, with the development and deepening, the new problems and contradictions gradually displayed, mainly displays in:1) A part of reserves could not effectively use because local still existed certain control area and retention area.2) In the present well pattern condition, thin and poor reservoir water flooding effect is poor, because it is difficult to establish effective displacement pressure gradient.3)Profile use rate is still low, and hierarchical differences is serious.4)The natural decreasing partial high because water injection is irrational structure.5)The cognition about the underground water-oil distribution law is difficult to meet the need of tapping and adjustment.On the basis of previous studies, taking the whole reservoir as the target and well groups as a unit, the paper made full use of seismic, drilling, logging, core analysis, formation testing, production test and performance data, to carry out recharacterization of the reservoir using detailed reservoir description in terms of the reservoir structure fracture distribution characteristics, subdivided sedimentary facies, reservoir characterization, oil, gas and water property and distribution, reservior pressure, temperature, driving types as well as reserves recaculation etc. By means of conventional reservoir engineering and numerical simulation, through in-depth study of the production characteristics suah as oil and water movement, water-cut variation, pressure system, injection-production capability, producing reserves, reasonable injection-withdrawal ratio and water injectivity etc, theproduction technical limits during mid and high water-cut stages of the reservoir have been determined. The development level by waterflooding as well as development effect was evaluated, to find out the major factors affecting reservoir development. The future potential of the reservoir development has been analyzed from three aspects, namely, well pattern infilling adjustment, restoring the production performance of flank high water-cut wells by sidetracking and oil and water stimulation measures.This study evaluated WX3block development present situation, and found the constraint bottleneck to efficient develop this block. Drawing lessons from domestic and international low permeability oilfield fine water injection development model and its matching technology, this study developed these technology:fine reservoir description, subdivision of the single sand body and flow unit, fine water injection unit, reasonable injection-production ratio, etc. To maximize the water drive reserves producing degree, and improve water flooding efficiency, and improved block development effect is this study purpose.