特低渗透各向异性油藏平面波及系数计算方法  

Calculation of areal sweep efficiency for extra-low permeability anisotropy reservoir

作　　者：何聪鸽 范子菲[1] 方思冬 许安著[1] 

机构地区：[1]中国石油勘探开发研究院,北京100083 [2]中国石油大学(北京)石油工程学院,北京102249

出　　处：《油气地质与采收率》2015年第3期77-83,共7页Petroleum Geology and Recovery Efficiency

基　　金：国家科技重大专项"大型油气田及煤层气开发"(2011ZX05044)

摘　　要：特低渗透油藏常表现出非达西渗流和渗透率各向异性的特征,为了解决特低渗透各向异性油藏水驱平面波及系数的理论计算问题,通过构建考虑启动压力梯度的非达西流管模型,利用坐标变化将渗透率各向异性油藏转化为等效各向同性油藏,推导了特低渗透各向异性油藏五点井网油井见水时间和平面波及系数的计算公式。该方法可用于定量表征特低渗透各向异性油藏水驱平面动用程度,为特低渗透各向异性油藏开发设计和评价提供理论依据。以鄂尔多斯盆地某特低渗透各向异性油藏为例,利用该方法分析了启动压力梯度、渗透率各向异性系数和注采参数对特低渗透各向异性油藏平面波及系数的影响,结果表明,当油藏渗透率各向异性较强时,注入水沿主渗透率方向快速突进,导致平面波及程度低,可通过优化井排距、增大注采压差或者井网加密的方式,减小死油区,以提高注入水的波及程度。Non-Darcy flow and permeability anisotropy are the essential characteristics of the extra-low permeability reservoir. In order to solve the theoretical calculation problem of areal sweep efficiency for the extra-low permeability anisotropy reservoir,non-Darcy stream tube model was built taking the threshold pressure gradient into account,and the areal sweep efficiency formula and water breakthrough time formula of five-spot well pattern were derived by using of coordinate transformation method to change anisotropy reservoir into an equivalent isotropy reservoir. This method can be used to quantitatively characterize the produced degree of the extra-low permeability anisotropy reservoir by water flooding,and provide theory basis for development and evaluation of the extra-low permeability anisotropy reservoir. Taking an extra-low permeability anisotropy reservoir of Ordos Basin as an example,we analyzed the effect of threshold pressure gradient,permeability anisotropy,well spacing and pressure difference on areal sweep efficiency with this method. The case study shows that when the permeability anisotropy degree is strong,the injected water will preferentially flow along the high permeability direction resulting in the unbalanced development. The adjustment of well spacing and row spacing,the rise of pressure difference and well pattern infilling are effective measures to decrease the dead-oil zone and to increase water flooding swept area.

关 键 词：特低渗透油藏 渗透率各向异性 五点井网 启动压力梯度 平面波及系数 

分 类 号：TE348[石油与天然气工程—油气田开发工程]