The northern Sichuan Basin,spreading in the northern section of the Longmenshan Fault Fold Belt,is characterized by dramatic fluctuations in surface landforms,development of abdominal faults,and low-quality seismic data,resulting in difficulties in clarifying relevant structures.The key target formation,the Mid-Permian Qixia Fm,is deeply buried with thin reservoirs and high heterogeneity,which brings great challenges to seismic prediction.Under such circumstances,researches have been conducted jointly in terms of seismic data acquisition,processing and interpretation,and finally some relevant seismic survey technologies were developed suitable for surface/underground complex structures.Through surface structural surveys,dynamic deep-well lithologic identification,single-point detector deployment and process optimization,acquisition parameters can be excited.In addition,by using an observation system with high coverage,wide azimuth and huge displacement,quality of acquired seismic data can be enhanced dramatically.Seismic imaging technologies for complex structures have been developed to enhance the quality of images for deep formations.These technologies are dominated by microscopic logging-constrained tomography static correction,high-resolution processing with fidelity and amplitude preservation and all-around PSDM in an angular domain.By using high-resolution gravity,magnetic and electric data,details related to geological structures and faults can be identified.In combination with fine seismic data interpretation,structural details and fault features can be verified effectively.Based on forward modeling and fine seismic calibration of reservoirs in individual wells,suitable attributes can be identified for predictions related to the distribution of reservoirs.By using all these auxiliary technologies,a large-scale structural-lithologic composite trap with a total area of 1 223 km2 has been discovered in the northwestern Sichuan Basin.The Shuangyushi-Jiangyou area as a whole distributes on structural highs.In the areas to the south of Shuangyushi,the Qixia Fm dolomite reservoirs of platform margins are continuously developed.In conclusion,these auxiliary technologies can effectively allow trap identification and thin reservoir prediction in complex structures in the study area.In addition to clarifying the exploration orientation and providing a necessarily technical supports for well deployment,these technologies help to accelerate the construction of demonstration projects for the exploration and development of deep marine carbonate formations.%四川盆地西北部地区处于龙门山断褶带北段,地表地势变化剧烈、地腹断层发育、地震资料品质差、构造落实难;主要目的层——中二叠统栖霞组埋藏深、储层薄、非均质性强、地震预测难度大.为此,通过开展地震采集、处理、解释联合攻关,形成了适合地面、地下双复杂构造的地震勘探配套技术:①通过表层结构调查、动态井深岩性识别、单点检波器埋置工具及工艺优化激发接收参数,采用高覆盖、宽方位、大偏移距观测系统,提高地震资料采集品质;②形成以微测井约束层析静校正、保真保幅高分辨率处理、全方位角度域叠前深度偏移为主的复杂构造带地震成像技术,提高地震资料深层成像质量;③利用高精度重磁电资料提取地质结构、断裂等信息,结合地震资料精细解释,落实构造细节和断裂特征;④基于模型正演和单井储层地震精细标定,优选属性预测储层分布.运用上述配套技术,新发现川西北部地区1 223 km2大型构造—岩性复合圈闭,双鱼石—江油地区整体处于构造高带,双鱼石以南地区栖霞组台缘带白云岩储层连片发育.结论认为,该配套技术较好地解决了该区复杂构造带圈闭落实和薄储层预测等难题,明确了勘探方向,为井位部署提供了技术支撑,加快了深层海相碳酸盐岩气藏勘探开发示范工程的建设步伐.
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