安塞特低渗透油藏合理开发井网系统研究

鄂尔多斯盆地安塞特低渗透油田由于存在天然裂缝或人工压裂裂缝,造成了储集层平面渗透率的方向非均质性。该油田以往采用正方形九点注水开发井网,存在沿裂缝方向油井见效、见水快,而裂缝两侧油井见效差或不见效等问题。以该油田具有代表性的坪桥区特低渗透油藏为例,通过数值模拟研究,对比分析了正方形反九点井网、菱形反九点井网和矩形五点井网的特点和开采效果,并对矩形井网的井排距和井距进行了优化。研究结果表明:在特低渗透油藏开发初期,菱形反九点井网开发效果好于正方形反九点井网,沿裂缝方向线状注水的矩形五点井网更适合特低渗透油藏开发;矩形五点井网可以对油井和注水井进行大型压裂,在提高单井产能和注水波及体积的同时可防止油井暴性水淹,通过适当延长沿裂缝方向的井距(最优井距为450～500m)、缩小垂直裂缝方向的排距(最优排距为150m),可以提高油井均匀受效程度和开发效果。图5表3参2(侯建锋摘)

Reasonable well pattern study for ultra-low permeability reservoirs in Ansai oil field, Changqing oil complex.

Ansai oil field in Ordos basin is a ultra low permeability reservoir with natural and induced fractures, which caused serious lateral heterogeneity of permeability in the reservoir. For the conventional square well pattern used in oilfield development, production wells along fracture direction respond rapidly and water cut rise quickly too, but the production wells on both sides of fractures are less effected. Pingqiao reservoir having the general character of ultra low permeability reservoir is used as a case study. Through reservoir simulation, the authors analyzed and correlated production results of reverse square 9 spot well pattern, reverse rhombus 9 spot well pattern and rectangular 5 spot well pattern and optimized well row spacing and well spacing of rectangular 5 spot well pattern. The study results show that reverse rhombus 9 spot pattern is more efficient than reverse square 9 spot pattern in the early period and rectangular 5 spot pattern, since we can fracture its production wells and injection wells on a large scale, thus its production rate and water injection efficiency can be enhanced, and production wells can be prevented from rapid water breakthrough, by enlarging the well spacing in fracture direction (the most optimal well spacing is 450 500m) and shortening well row spacing in perpendicular direction (the most optimal spacing is 150m), we can make production wells taking uniform injection effect and enhancing developing efficiency.