摘要
为了让致密油气藏分段压裂时形成的水力裂缝和天然裂缝相沟通，形成复杂缝网，提高水力压裂增产效果，采用数值模拟方法研究了水平井缝网压裂的缝间距优化问题。建立了均质、各向同性储层内二维水力裂缝的诱导应力差模型；根据裂缝转向机理，推导出了缝间最大诱导应力公式，确定了最优间距。结合现场数据，计算了泊松比为0.2～0.5、缝间距为40～90 m时的缝间诱导应力。计算结果表明：地层的泊松比越小，裂缝的诱导应力差越大，诱导应力的传播距离越远；随着与裂缝距离的增加，诱导应力差呈现先增大后减小的趋势；当2条裂缝之间的距离为最优间距时，缝间的诱导应力差最大。研究表明，优化裂缝之间的缝间距，可以使裂缝之间的诱导应力差达到最大值，形成复杂的裂缝网格，提高油气与井筒之间的连通性。研究结果为低渗透油气藏缝网压裂时的裂缝优化设计提供了参考。
During the staged fracturing in horizontal wells ,in order to form a complex fracture network and improve the post-fracturing performance ,a numerical simulation method was used to optimize fracture spacing of “fracture network”in horizontal well .Based on fracture diverting mechanism ,homogeneous and isotropic 2D maximum induced stress anisotropy model was built ,maximum induced stress equation be-tween fractures was deduced ,and the optimal fracture space was worked out .According to field data ,The induced stress anisotropy was calculated under Poisson’s ratio of 0.2 0.5 and fracture spacing of 40 90 m . The result showed the lower the Poisson’s ratio ,the higher the fracture induced stress difference ,the lon-ger the induced stress would propagate ,as the distance increased ,the induced stress difference first in-creased and then decreased ,when the spacing between two fractures was optimal ,the induced stress differ-ence was maximum .The study showed the optimal spacing between fractures could maximize induced stress difference between fractures ,facilitating the formation of complex fracture network ,and improving the con-nectivity between oil and gas and wellbore .The study results provided a new approach for fracturing opti-mization in low permeability oil and gas reservoirs .
出处
《石油钻探技术》
CAS
CSCD
北大核心
2014年第1期86-90,共5页
Petroleum Drilling Techniques
基金
国家自然科学基金项目"页岩气藏水平井完井与多级压裂增产的基础研究"(编号:51210006)和国家自然科学基金项目"页岩气开采岩石力学"(编号:51234006)资助
关键词
水平井
低渗透油气藏
缝网压裂
裂缝间距
诱导应力
horizontal well
low permeability reservoir
fracture-network fracturing
fracture spacing
induced stress
