摘要
针对鄂尔多斯盆地SD区块盒8段储层低孔低渗、非均质性强、常规压裂裂缝形态单一等问题,基于断裂力学理论,考虑缝内流体压降,结合盒8段储层岩石力学参数,开展暂堵压裂裂缝与初次压裂裂缝在整个接触过程中的相互作用力学研究。计算分析了不同裂缝走向、井斜角、方位角等参数对压裂裂缝参数的影响规律,起裂压力随井斜角和方位角的增加而减小;起裂角随井斜角增加而减小直至为0°,随方位角先增加而后减小。通过制备人工水泥试样,利用大尺寸真三轴物模实验系统模拟了暂堵压裂中新缝起裂及其转向行为,评价了不同井斜角、方位角下新缝起裂、转向及延伸行为和起裂压力及裂缝改造面积等参数。实验结果表明:井斜角增大,初次及二次起裂压力呈减小的趋势,裂缝更易转向且改造面积越大。井斜角相同时,裂缝起裂压力随井筒方位角增加而逐渐减小,裂缝改造面积随方位角增加而增大。方位角90°螺旋射孔相比方位角0°螺旋射孔形成的裂缝更为复杂,定面射孔可调控水平井破裂压力及初始破裂位置,初始破裂产生于射孔井筒界面、孔道中部等不同位置,控制射孔射角介于75°~90°。研究结果为低渗透致密砂岩气藏暂堵压裂设计提供了依据。
This study addresses the challenges presented by the reservoirs in He-8 member in SD block of Ordos Basin,characterized by low porosity,low permeability,strong heterogeneity,and conventional fracturing fracture shapes.Utilizing fracture mechanics,this research examines the interactions between temporarily blocked fractures and the initial fracture throughout their entire contact period.Key considerations include fluid pressure drop within the fracture and the rock mechanics parameters of the reservoirs in He-8 member.The study systematically analyzes the influence of various parameters such as fracture strike,well deviation angle,and azimuth angle on fracturing fracture parameters.Notable findings include:Fracturing pressure decreases with increasing well deviation angle and azimuth angle.The initiation angle diminishes as well inclination increases,reaching a nadir before decreasing further with azimuth angle adjustments.Using artificial cement samples and a large-scale experimental system with realistic triaxial physical models,the study simulates the initiation,turning,and propagation behaviors of new fractures in temporary plugging fracturing. The behaviors of initiation, steering and extension of newly formed fractures at different wellinclination and azimuth angles were evaluated along with the parameters such as fracture initiation pressure and fracture stimulatedarea. The experimental results reveal: Both initial and secondary fracture pressures tend to decrease as well inclination increases,making fractures more prone to turning and significantly enlarging the modifiable area. With consistent trap inclination, fractureinitiation pressure decreases and the fracture modification area expands as bore azimuth increases. Fractures resulting fromazimuthal 90° spiral perforation exhibit greater complexity compared to those from azimuthal 0° spiral perforation. Additionally,fixed surface perforation techniques can regulate fracture pressure and the initial fracture positions in horizontal wells,recommending a perforation angle between 75° and 90°. These findings offer valuable insights for the design of temporary plugsand fracturing strategies in low-permeability tight sandstone oil and gas reservoirs.
作者
孔祥伟
许洪星
时贤
陈杭
KONG Xiangwei;XU Hongxing;SHI Xian;CHEN Hang(School of petroleum engineering,Yangtze University,Wuhan,Hubei 430100,China;Hubei Key Laboratory of Oil and Gas Drilling and Production Engineering,Yangtze University,Wuhan,Hubei 430100,China;CCDC Changqing Downhole Technology Company,Xi'an,Shaanxi 710000,China;School of Petroleum Engineering,China University of Petroleum(East China),Qingdao,Shandong 266000,China;The 10th Oil Production Plant of PetroChina Changqing Oilfield Branch,Qingyang,Gansu 745100,China)
出处
《油气藏评价与开发》
CSCD
北大核心
2024年第3期391-401,共11页
Petroleum Reservoir Evaluation and Development
基金
国家自然科学基金项目“页岩油立体井网CO_(2)增能压裂空间应力场重构和裂缝扩展规律研究”(52374027)
国家自然科学基金项目“高温高压气井环空压力动态预测及安全评价研究”(52074018)
中国石化科技部项目“川西中浅层致密砂岩气藏体积压裂关键技术研究”(P22047)。
关键词
真三轴
暂堵压裂
起裂扩展
破裂压力
起裂角
裂缝改造面积
true triaxial
temporary plugging fracturing
fracture initiation and morphology
breakdown pressure
fracturing angle
fracture stimulation surface area
