不同坡度背景下生物礁沉积结构及差异演化特征
——以开江—梁平海槽西侧长兴组为例

Sedimentary structure and differential evolution characteristics of reefs under different slope backgrounds: a case study of Changxing Formation on the west side of the Kaijiang-Liangping Trough

宋昊 胡明毅 陈旭 王胜利 左洺滔 邓志强

长江大学地球科学学院，湖北 武汉 430100 中国石化集团国际石油勘探开发有限公司，北京 100029

School of Earth Sciences, Yangtze University, Wuhan 430100, China International Petroleum Exploration and Production Corporation, SINOPEC, Beijing 100029, China

开江—梁平海槽西侧长兴组发育大规模台缘礁滩体沉积，但礁滩储层内部差异大，非均质性较强，制约了研究区天然气的高效开发。文中综合利用地震、测井、钻井资料，在对台缘生物礁外部轮廓、内部形态和平面展布研究的基础上，探讨长兴组不同区块台缘生物礁的生长发育特征。研究结果表明：1）依据坡度变化，可将研究区台缘礁滩沉积划分为断控陡坡型、沉积陡坡型、沉积中等陡坡型和沉积缓坡型4种；研究区自西北到东南方向，坡度逐渐减小，礁滩复合体垂向沉积厚度减薄，而横向展布变宽。2）受古地貌和海平面频繁变化的影响，海槽西侧发育大规模单个礁体，整体分布不均，海槽西侧北部生物礁以垂向加积为主，中部呈现加积和弱进积特征，南部具有缓坡进积特征。3）通过对海槽西侧长兴组生物礁的差异沉积特征研究，从成礁岩性、沉积厚度及空间展布3个方面，分段建立了长兴组生物礁滩4个阶段的差异演化模式。

The large-scale platform marginal reef-shoal deposits are developed in the Changxing Formation on the west side of the Kaijiang-Liangping Trough. However, large inner differences in the reef-shoal reservoirs and strong heterogeneity restrict the efficient development of natural gas in the study area. In this paper, using seismic, well logging and drilling data, on the basis of the research on the outer contour, inner shape and plane distribution of platform edge reefs, the growth and development characteristics of the platform platform edge reefs in different blocks of the Changxing Formation are discussed. The research results show that: (1) the platform marginal reef?鄄shoal deposits in the study area are divided into four types of fault-controlled steep slope type, sedimentary steep slope type, sedimentary medium steep slope type and sedimentary gentle slope type according to the change of slope angle, the slope angle of the study area from northwest to southeast is gradually reduced, and the vertical sediment thickness of the reef?鄄shoal complex is reduced and the lateral spread is widened; (2) affected by the frequent changes of paleomorphology and sea level, large-scale single reefs are developed on the west side of the trough, and the overall distribution is uneven, the reefs in the northern part of the west side of the trough are dominated by vertical accretion, the central part is characterized by aggravation and weak progradation, and the southern part is characterized by gentle slope progradation; (3) through the study of the differential sedimentary characteristics of the biological reefs in the Changxing Formation on the west side of the trough, the differential evolution patterns of the four stages of the Changxing Formation reefs are established in sections, which are summarized into three aspects: reef formation lithology, sediment thickness and spatial spread characteristics.

10.6056/dkyqt202206011