Research And Appliance Of Horizontal Wells Drilled High Water Cut Stage Of Development For Remaining Oil Development In Pucheng Oilfield

Pucheng field has already entered into late high water cut stage at present since 20years of rapid development. It is very difficult for conventional methods to meet therequirements of field development in economic results. For this, horizontal welldevelopment experiment has been carried out in Pucheng field successfully. Experimentshows that after new development technique being applied in this kind of reservoir,recovery has got improved and there is more space for remaining oil development. Thetechnique is of good and wide application value in this kind of reservoir. Content that thepaper is discussing is one of technical problems needing urgent solution in high water cutfield. After fine description of reservoir and ration calibration of remaining oil, horizontalwell technique has been studied for remaining oil development. Main achievements are:1. Taking lower S1 reservoir as an example, characteristics of high water cut reservoirhas been studied; on the basis of fine correlation analysis of single wells, through accurateinterpretation of seismic data and combining with dynamic data of development, structuralmaps of top sands have been made in 2m vertical interval and in the scale of 1:5000.2. according to sedimentary features of delta of lower S1 sand and variation ofelectric log curves, it is divided into five micro facies including underwater distributarychannel, mouth bar, sand sheet, far sand and mud flat. Corresponding composite columnof sedimentary facies has been compiled according to core observation. After fineevaluation of lateral and vertical distribution of flow unit oil layer, contour maps of netpay and physical properties have been made.3. on the basis of 3D geologic model establishing, numerical simulation has beenadopted to study distribution law of remaining oil in target area, which shows that majorsubzone of lower S1 reservoir has wide flooded area, nearly covering the whole blockwith good rinsing effect and high recovery. Reserve of remaining oil is low which onlydistributes in structural high, the fault and the part where oil layer is thinning andpetrophysical property is becoming poor.4. the formula calculation method are analogy method to vertical wells are adopted topredict productivity of horizontal wells. Actual production data regression and reservoirnumerical analogue of horizontal wells are used to predict production declining law of thewells which shows that declining law coincides with hyperbolic declining law. Numericalanalogue method mainly studies the effect on horizontal well development including the factors such as horizontal length, inhomogeneity of inner oil layer, oil drain, net thicknessof horizontal well and capacity supplement. By studying application selection technique,accurate 3d modeling technique of target area, optimized strike design of horizontalinterval and target reservoir selection of horizontal well, theory support has been providedfor reservoir geologic design of horizontal single well.5. Base on the fine reservoir description, starting from the geological and reservoircharacteristics, in accordance with the relationship of the structure, reservoir, oil-waterrelation, remaining distribution, productivity and other details one by one to grasp andscreening suitable for the reservoirs of horizontal wells, well point, make full use ofexisting data, combining static and dynamic, and quantitative analysis of the target area ofremaining oil distribution law and the potential to optimize the target. Based on remainingoil distribution and potential evaluation to study the remaining oil of the potentialinterference type, the top of the thickness reservoir, wells hydrodynamic retention type,fault sheltered type and well network imperfections type, proposed the horizontal wellsdeployment for the remaining oil-rich type.6. By the analysis, research, summarize of the problems of 14 horizontal wells suchas the P1-P1 well, P5-CP5 well, P4-P1 well and Wen51-P14 well that extending the stableproduction period of sidetracking horizontal well to improve the recovery, improvedevelopment response and economic efficiency significantly, popularization andapplication of the techniques for further development of the horizontal wells.