各向异性油藏倾斜裂缝水平井非稳态压力模型

Model of transient pressure behavior for horizontal wells with inclined fractures in anisotropy reservoir

 任宗孝¹ 吴晓东¹ 何晓君² 李金海³ 左翼¹ 娄尔标⁴

中国石油大学（北京）石油工程学院教育部重点实验室，北京 102249 中国石油青海油田测试公司，青海 茫崖 816400 中国石油青海油田公司采油三厂，青海 茫崖 816400 中国石油塔里木油田公司油气工程研究院，新疆 库尔勒 841000）

MOE Key Laboratory of Petroleum Engineering, China University of Petroleum, Beijing 102249, China Test Company, Qinghai Oilfield Company, PetroChina, Mangya 816400, China No.3 Oil Production Plant, Qinghai Oilfield Company, PetroChina, Mangya 816400, China Research Institute of Oil and Gas Engineering, Tarim Oilfield Company, PetroChina, Korla 841000, China)

 由于地质沉积过程中岩石颗粒大小取向不同，导致大部分油藏都是各向异性油藏；各向异性油藏又会导致水力裂缝与水平井筒之间存在一定的倾角。但目前压裂水平井非稳态压力模型大都在各向同性油藏裂缝垂直井筒前提下建立的。为解决现场实际问题，首先通过坐标变换将各向异性油藏等效转换为各向同性油藏，之后基于Ozkan源函数应用坐标平移及坐标旋转原理，建立考虑裂缝与水平井筒之间存在任意倾角的分段压裂水平井非稳态压力模型。经计算，当裂缝与平面最大渗透率夹角为90°时，渗流阻力最小；夹角在50~90°变化时，倾角的改变对分段压裂水平井压力影响较小。随着裂缝间距的降低，第一径向流逐渐消失，试井曲线会出现“驼峰”状凸起。

 Different geological grain sizes and orientation in the process of rock sedimentation cause the anisotropy of the most reservoirs. Reservoir anisotropy leads to the angle between hydraulic fracture and horizontal wellbore. But currently most transient pressure model for fracturing horizontal wells is established under the precondition of vertical cracks. In order to solve the actual problem, through the coordinate transformation, anisotropic reservoir is converted into equivalent isotropic reservoir. Then based on the Ozkan source function coupled with coordinate rotating and coordinate translation principles, the fractured horizontal well pressure model is established with any fracture angle. Through calculation, reservoir flow process can be divided into four stages: linear flow, the first radial flow, double radial flow and pseudo radial flow. When the angle between the fracture and the maximum plane permeability is from 50° to 90°, the angle change has less affection on the pressure behavior of fractured horizontal well. The first radial flow gradually disappears as the fracture spacing becomes less and the well test curve will appear in a "hump" shape.

10.6056/dkyqt201701017