第38卷第6期 2017年12月
文章编号：1001-3873(2017)06072306
新疆石油地质
XINJIANG PETROLEUM GEOLOGY DOI; 10.7657/XJPG20170615
Vol.38,No.6 Dec.2017
断块油气藏开采对地应力和破裂压力的影响规律
赵凯",赵文龙”石林”，李波”高辉"刘顺"
（1.西安石油大学石油工程学院，西安710065;2.中国石油集团长城钻探工程有限公司，辽宁盘锦124010；
3.中国石油新疆油田分公司采气一厂，新疆克拉玛依834000）
摘要：地应力和破裂压力是油戴实施压裂增产措施中所必雷的基础参数，断块油气截长期开采后，地应力和破裂压力会发生较大变化。根据多孔介质弹性力学理论，分析了断块油气藏储集层压力衰端对地应力大小和方向的影响，在此基础上，研究了压裂起聚和延伸的变化规律。结果表明，断块油气藏储集层压力衰竭导致地应力非均匀衰减，压裂过程中裂缝延伸压力线性降低，裂缝延伸方向发生偏转，且在压力衰竭初期偏转快，后期编转慢；储集层压力衰竭导致裸限井起裂压力线性降低，断块油气藏开采后破裂压力的降低幅度较传统无限大均质油藏更大，且定向并压裂施工的难易程度与井眼轨迹的关系发生了变化，对于断块油气藏面言，若在开发后期进行压裂增产作业，可根据压力
衰竭程度合理设计并限轨迹，降低压裂作业的施工难度。关键词：断块油气藏；压裂开采；压力衰竭；地应力；破裂压力
中图分类号：TE21
文献标识码：A
Influences of Oil and Gas Production on In-Situ Stress and Fracture Pressure in Fault-Block
Reservoirs
ZHAO Kai', ZHAO Wenlong, SHI Lin', LI Bo', GAO Hui', LIU Shun
(1.College of Petroleum Engineering, Xi'an Shiyou University, Xi'an, Shaanxi 710065, China; 2.Greatwall Drlling Company, CNPC, Panjing, Liaoning 124010, China; 3.No.1 Cas Production Plant, Xinjiang Oilfield Company, PetroChins, Karamay, Xinjiang 834000, China) Abstract: As the basic parameters needed in reservoir fracturing stimulation, in-situ stress and fracture pressure will change significantly after a long period of production in fault-block reservoirs, According to the elastic mechanics theory for porous media, the paper analyzes the influences of fault-block reservoir pressure depletion on in-situ stress size and direction, based on which the variations of crack initia-tion and extension are studied. The results show that fault-block reservoir pressure depletion results in inhomogeneous attenuation of in-si-tu stress, fracture extension pressure declines linearly during fracturing, fracture extension direction deflects rapidly at the early stage of pressure depletion and relatively slowly at the late stage of pressure depletion; reservoir pressure depletion leads to the linear decline of erack initiation pressure in an open hole. The fracture pressure reduction extent in fault-block reservoirs is largcr than that in conventional homogeneous reservoirs after the reservoirs are put into production, and the relationship between fracturing feasibility degree and wellbore trajectory in directional wells changes. For fault-block reservoins, wellbore trajectory should be designed reasonably according to pressure
depletion extent to reduce the difficulties of fracturing operation if fracturing stimulation is needed at the late production stage, Keywords: fault-block reservoir, fracturing stimulation; pressure depletion; in-situ stress; fracture pressure
地应力和破裂压力是实施压裂增产措施中所必需的基础参数"-5。油气田长期开采会造成储集层压力衰竭，诱导地应力发生改变，进而影响裂缝的破裂压力（包括裂缝的起裂压力和延伸压力)6-9，此时若仍按开发前期的数据进行方案设计和投产，易使压裂效率过低。目前，中国很多油气田已经进人开发中后期，地应力和破裂压力较开发初期均发生了明显的改变，如马东油田港深10-18井在前后两个开发时期（1999年7月和2000年6月）进行油层压裂改造时的实际地层破裂压力分别是78.4MPa和73.0MPal"，准
确评价油田开发中后期的地应力和破裂压力，是保障压裂作业安全、经济有效的关键。
针对以上问题，国内外学者也开展了诸多研究。文献[11]根据线弹性理论，在单向压缩且忽略横向变形的条件下，得到了均质储集层开采对水平地应力影响的评价方法，认为压力衰竭造成水平地应力均匀衰减，即最大水平地应力和最小水平地应力的改变量相等;文献[12]和文献[13]采用文献[11]提出的评价方法对储集层开采后的地应力进行了计算，并将计算结果与实测地应力数据进行了对比，发现文献[11]提出
收稿日期：2017-08-05
修订日期：2017-10-18
基金项日：国家白然科学基金（51604225）；中国石油科技创新基金项日（2016D-5007-0207）
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