| There are three exploration blocks in total, including the one between Mianzhu and Mian’yang, Pengzhou and Dayi, Wenjiang and Zhongjiang, which are cities of Sichuan province, covering an area of9535.944km2. Five development blocks, including Luodai and Xindu districts in Chengdu, Deyang Xinchang, Deyang Ma Jing and Deyang Dongtai-Hop Hing field, cover an area of1034.215km2. In the study area, drilling strata sequence from top to bottom is as follow:the quaternary (Q), the cretaceous (K), The upper Jurassic Penglai town group (J3p), The Middle Jurassic of Shaxi Miao group (J2s) and the Shaxi Miao group (J2x), Qian Foya group (J2q), the lower Jurassic Bai Tian Ba group (J1b) as well as the Triassic Xujiahe Formation (T3x). Among them, in the town of Penglai Suining group, the shallow layer group, Shaxi Temple group and the deep Xujiahe formation is the main gas bearing continental.Jurassic gas reservoir In western Sichuan is the main gas reservoir of Southwest Oil and Gas Company. A remarkable success has been made through many years of continuous exploration and development in this natural gas exploration area. Reservoir production has risen steadily. At the same time, the development of Jurassic in West Sichuan area shows that in addition to Marai Kedanao in the production stage, Luodai Suining group, Penglai group gas reservoir, Penglai group gas reservoir in Xinchang have entered a decline period, the cumulative yield has reduced year by year. Reserves and production task is arduous. Exploration and development are hard to move on. Resources to succeed in the key period and finding new exploration to replace the main battlefield have become a pressing matter of the moment. Therefore, Southwest Oil and Gas Company should pay more attention to the problems mentioned above.As a matter of fact, the exploration in the West of Sichuan is too intensive and unscientific in some way. There are still many potential areas with remaining richness of resources, accounting for74%, in the total amount of natural gas in shallow reservoirs. Among them, Marai-Shifang area of Shifang9, Shifang16, Shifang17, Shifang20wells fracturing test are obtained industrial gas flow, in some drilling and even get high-yield industrial air, also confirmed the good exploration prospect in this area. Guanghan-Jintang area wide gold5, gold6wells were industrial capacity, achieved a major breakthrough in natural gas exploration in this area in West Sichuan area, confirmed the Jurassic, especially the town of Penglai group gas reservoir has good potential of exploration and development. The new complex area of Wenjiang is far from being fully explored, which can go for the goals of increasing reserves and production for West Sichuan Jurassic in the near future.With the rich drilling and seismic data in this region as the basis, the calibration of each level of sequence interface, maximum flooding surface, can be used to identify long-term, medium-term and short-term base level cycle sequence stratigraphic division and correlation based on the relative position of the gas field, Middle Jurassic strata in the sequence stratigraphic framework and the long term base level cycle sequence of the calibration, by comparing the well seismic profile interpretation, sand group division and correlation were established in the West Sichuan Depression Jurassic strata, sand group division principle and the unity of. Among them, the town of Penglai was divided into4medium-term cycles and29short-term cycles.According to sedimentology and logging geology principle, sign system of the single well core section facies, subfacies and microfacies can be decided. And the lithologic and electric relations based on core and well logging data of coring wells has been established, determining the different facies, sub facies and logging facies. Facies characteristics and rock-conversion model, under the comparison between well profile and well seismicity, initially established can reflect the basic characteristics of sedimentary facies types of system geometry and earthquake unit.Sedimentology and logging geology principle, the single well core section facies, subfacies, microfacies sign system, and established the lithologic and electric relations based on core and well logging data of coring wells, determine the different facies, sub facies and logging facies facies characteristics and rock-conversion model, well profile well seismic contrast used, initially established can reflect the basic characteristics of sedimentary facies types of system geometry and earthquake and unit.In the drilling of sedimentary facies, seismic facies analysis, combined with the regional sedimentary background, provenance analysis, initially identified in West Sichuan area, the shallow sedimentary facies and key areas, key sand microfacies distributionUsing a variety of provenance analysis methods, including detrital composition analysis, dip log, outcrop paleocurrent measurements, source direction of Jurassic clastic rocks in West Sichuan depression and paleocurrent analysis. Research shows, the West Sichuan depression Shaxi Temple group paleocurrent direction to the North West to the southeast, source mainly from the northern Longmen mountains; Penglai town group paleocurrent direction is NW-SE and NE-SW direction, source mainly from the northern part of the Longmen mountains and the middle, characterized by multi sources.Shaxi temple in the North East Group developed braided river-Lake Sediments in the Western Sichuan depression. Braid river delta front deposition, are\mainly distributed in Xiaoquan Xinchang, Zhi Xinchang, Zhongjiang-huilong districts.The group of Penglai Town in Western Sichuan depression from west to East, alluvial fan and lake sediments. Depression is mainly belongs to braided river delta system, braided river delta plain and delta front and prodelta facies including development. In the regional sedimentary facies of single well facies, based on the analysis, combined with seismic reflection structure and amplitude, wave impedance, pixel imaging characteristics, determine the top two gas reservoir five, Peng three gas reservoir ten sets of a total of15sets of sand group sedimentary microfacies distribution map. Research shows, depression internal Penglai town group delta plain, extensively developed distributaries, channels, mouth bar, natural levee, crevasse splay deposits, further confirmed the sedimentary background has a longitudinal multiple sets of sand body, the plane laminated sandstone is widely distributed "bowl of sand rich" in Western Sichuan depression.This study is mainly based on the geological significance of the District, in the framework of sequence stratigraphy in continental basins of comprehensive research, the geological and seismic technology related, the sequence stratigraphy and seismic technology are organically combined together, to carry out fine strata and sand group contrast; in the provenance analysis basis, sedimentary facies model are established, and summed up the rules of sedimentary evolution of the study area, further provide the theory and method of the good foundation for the work in the area of the gas reservoir explorationThe organic combination of sedimentology and high resolution sequence stratigraphy research explains the formation mechanism and evolution of sequence stratigraphyc from the genetic mechanism. Establish a sedimentary system and sedimentary microfacies development mode. On that basis, the formation of the effective reservoir prediction will be achieved, thus forming a unified comparison scheme of the sand group level.According to well and seismic data, reservoir conceptual model for guiding the seismic reservoir lateral prediction.From the anatomy of dense well network, quantitative reservoir geological knowledge database can be established. Under various conditions of analysis of seismic attributes and constraints, the distribution of effective reservoir prediction is predictable whereas reservoir hierarchical prediction and charting of sedimentary depositional system in complete layer and sand group microfacies going on. |
PDF Full Text Request