摘要
为了破解四川盆地西部坳陷合兴场地区三叠系上统须家河组二段上亚段特低孔隙度、特低渗透率致密砂岩储层井筒远端裂缝识别难题,明确裂缝对该区气井产能的控制机理,基于岩心裂缝观察、薄片微裂隙分析结果,结合电成像测井数据,对比了天然裂缝与诱导缝的成因机制、产状及图像特征差异,建立了天然裂缝电成像识别图版;开展了裂缝走向与现今地应力方向匹配性、裂缝参数与气井天然气无阻流量相关性研究,明确了声波远探测技术识别井旁地质体的方法流程。研究结果表明:①该区须二上亚段以低角度裂缝为主(占比55.9%),高角度缝(占比27.5%)与斜交缝(占比16.6%)多呈开启状态,高角度缝和斜交缝有效性较好;②气井产能受裂缝走向控制,近E—W向、NW—SE向裂缝因与现今最大主应力方向一致,单井天然气无阻流量可达52.95×10^(4)m^(3)/d,而N—S向裂缝对应井产能则不足5×10^(4)m^(3)/d,有效裂缝密度与气井无阻流量呈正相关;③依据声波远探测井筒远端裂缝识别方法,可以准确刻画井旁40 m内的远端裂缝。结论认为,所建立的地质—工程一体化裂缝评价体系有效解决了井筒远端裂缝识别难题,可以优化断缝体储层开发方案设计;近E—W向裂缝发育带为该区水平井轨迹优选目标区。
It is challenging to identify fractures outside wellbores in the tight sandstone reservoirs with ultra-low porosity and permeability in the upper submember of the second member of the Upper Triassic Xujiahe Formation(hereinafter referred to as T3x23)in the Hexingchang area of the Western Sichuan Depression of the Sichuan Basin.To address the challenge,and clarify the controlling mechanism of fractures on gas-well productivity in this area,electrical imaging identification charts for natural fractures were established by comparing genetic mechanisms,occurrences and image characteristics of natural versus induced fractures,based on core fracture observations,thin-section micro-fracture analyses,and electrical imaging log data.Moreover,the consistency between fracture strike and current in-situ stress direction,as well as the correlation between fracture parameters and open flow potential(OFP)of gas wells were investigated,thereby defining a workflow for identifying near-wellbore geological bodies using acoustic remote detection technology.The results are obtained in four aspects.(i)T3x23 in the study area is dominated by low-angle fractures(55.9%),followed by high-angle fractures(27.5%)and oblique fractures(16.6%).The latter two are mostly open,indicating good effectiveness.(ii)Well productivity is controlled by fracture strike.Fractures oriented near E-W and NW-SE align with the direction of current maximum principal stress,resulting in single-well OFP up to 52.95×10^(4)m^(3)/d,whereas wells with N-S-strike fractures have productivity less than 5×10^(4)m^(3)/d.Effective fracture density shows a positive correlation with the OFP.(iii)The acoustic remote detection technology for identifying fractures outside wellbores can accurately characterize the fractures within 40 m around the wellbore.It is concluded that the established geology-engineering integrated fracture-evaluation system effectively enables the identification of fractures outside wellbores,thereby facilitating the optimization of development planning for fault-fracture reservoirs.The zones with developed near E-W-strike fractures are the targets for horizontal well trajectory optimization in this area.
作者
彭婷婷
秦启荣
何传亮
吴燕辉
王志文
PENG Tingting;QIN Qirong;HE Chuanliang;WU Yanhui;WANG Zhiwen(School of Geosciences and Technology,Southwest Petroleum University,Chengdu,Sichuan 610500,China;Southwest Measurement and Control Company,Sinopec Matrix Corporation,Chengdu,Sichuan 610100,China;Daqing Branch,China National Logging Corporation,Daqing,Heilongjiang 163412,China)
出处
《天然气勘探与开发》
2025年第5期37-47,共11页
Natural Gas Exploration and Development
基金
中石化经纬有限公司科研项目“合兴场地区测井—地震—地质一体化解释研究及应用”(编号:JWKT2212)。
关键词
声波远探测
远端裂缝识别
气井无阻流量
致密砂岩储层
三叠系上统须家河组
四川盆地西部坳陷
合兴场地区
Acoustic remote detection
Identification for fractures outside wellbore
OFP of gas well
Tight sandstone reservoir
Upper Triassic Xujiahe Formation
Western Sichuan Depression of Sichuan Basin
Hexingchang area
