特低渗透断块油藏不规则三角形井网有效动用系数计算及应用

针对断块油藏的布井方式,考虑特低渗透储层流体非线性渗流特征,从非线性渗流基本公式出发,应用流管积分法推导不规则三角形井网有效动用系数计算公式,并分析注采压力差、井网几何形状及非线性渗流曲线等因素对有效动用系数的影响,进而将研究成果应用于江苏油田花17断块井网评价中并提出井网调整方案.研究结果表明:均质各向同性特低渗透断块油藏适合部署等腰或近等腰三角形井网；当井网形状偏离等腰三角形程度较高时,存在引起有效动用系数突变的注采压力差和井距；渗透率较大的储层,宜通过放大注采压力差来提高有效动用系数,而渗透率较小的储层,缩小井、排距为更有效的手段.

Calculation and application of effective development coefficient for irregular triangular patterns in extra-low permeability fault block oil reservoirs

Based on the popular pattern shapes in fault block oilfields and the nonlinear characteristics of the fluids flow in extra-low permeability reservoirs,the expression of effective development coefficient was derived through the streamtube-integration method,and then the effects of pressure difference,well patterns geometry and the shapes of nonlinear flow curves on EDC were analyzed.The new theory was applied to evaluate the well patterns in Hua 17 Block in Jiangsu Oilfield,and a proposal for patterns adjustment was put forward.The results show that in homogeneous isotropic extra-low permeability fault-block reservoirs,the optimal well patterns are those in the shapes of isosceles or quasi-isosceles triangles;for a certain non-isosceles triangle pattern,there is a critical pressure difference and a critical well spacing value bringing the EDC on abrupt changes;and increasing pressure difference is an effective measure to improve the development effect for relatively higher permeability reservoirs while reducing well spacing or row spacing is effective for the relatively lower ones.