开江—梁平海槽南段长兴期沉积格局认识及油气勘探意义

The understanding of sedimentary pattern in Changxing period and significance for oil-gas exploration in the southern section of Kaijiang-Liangping Trough

邓志强 胡明毅 左洺滔

长江大学地球科学学院，湖北 武汉 430100 中国石油勘探开发研究院西北分院，甘肃 兰州 730000

College of Geosciences, Yangtze University, Wuhan 430100, China Research Institute of Petroleum Exploration and Development-Northwest, PetroChina, Lanzhou 730000, China

基于前人研究成果，文中利用大量钻井、测井及最新地震解释资料，开展了开江—梁平海槽南段长兴组沉积特征研究，以明确长兴期沉积格局及礁滩展布规律。研究表明：1）开江—梁平海槽南段长兴期依次发育碳酸盐岩缓坡和碳酸盐岩台地沉积，进一步划分为台坪、台地边缘、台内洼地等沉积相；2）开江—梁平海槽南段长兴期具有明显的“槽￣台”沉积分异格局，存在“两槽￣一洼￣两台”沉积格局；3）对研究区三维地震剖面精细刻画分析认为，城口—鄂西海槽有明显向建南西北部延伸的趋势，开江—梁平海槽南段台缘生物礁之间存在潮道沟通区内台内洼地，进而在建南及其周缘地区与城口—鄂西海槽水体相连，在海槽周缘发育台地边缘礁滩沉积。研究成果为川东地区长兴组生物礁滩气藏的勘探拓展了新领域。

Based on the previous research results in this paper, a few of drilling, logging and the latest seismic interpretation data are used to carry out the research on the sedimentary characteristics in the southern section of the Kaijiang-Liangping trough in the Changxing period, so as to clarify its sedimentary pattern and reef beach distribution law. The results show that: (1) carbonate slope and carbonate platform sedimentary are developed successively in Changxing period in the southern section of Kaijiang-Liangping trough, which can be further divided into platform, platform edge, intra-platform depression and other sedimentary facies types; (2) the southern section of Kaijiang-Liangping trough in Changxing period has an obvious "trough-platform" sedimentary differentiation pattern, and there is a sedimentary pattern of "two troughs-one depression-two platforms"; (3) through the detailed description and analysis of 3D seismic profiles in study area, it is believed that the Chengkou-western Hubei trough has an obvious trend to extend to the northwest of Jiannan. There are channels between the platform edge reefs in the southern section of Kaijiang-Liangping trough, which communicate with the platform depression in the area, and then connect with the water bodies of the Chengkou-western Hubei trough in Jiannan and its peripheral areas. The platform edge reef beach facies deposits are developed around the trough. The research results reveal a new field for the exploration of biohermal beach gas reservoirs in Changxing Formation in eastern Sichuan area.

10.6056/dkyqt202206010