Abstract: Under the background of tide-controlled coastline environment, the main sedimentary system of Kepingtage Formation in the Silurian is the tidal flat depositional system in Tazhong area of Tarim Basin. The sedimentary environment can be divided into intertidal zone and subtidal zone where the mud flat, mixed flat, sand flat and channel facies developed on the low ramp. By using the high-resolution stratigraphic theory and research methods, Kepingtage Formation can be divided into two long-term sequence cycles of LSC1 and LSC2, five medium-term sequence cycles and eleven short-term sequence cycles. The sedimentary environment is mainly subtidal zone and the main facies is channel facies in LSC1 cycle, while the sedimentary environment is intertidal zone and the sand flat is the main facies in LSC2. According to the data of Tazhong 11 Well and Tazhong 117 Well, the tidal channel and sand flat facies developed the main reservoirs in Tazhong area. The mud flat was mainly located at the top of the LSC1 and became the seals of oil reservoirs. The red mudstone overlying the Kepingtage Formation formed the cap-rocks of gas reservoir. Under the effective sealing of the overlying cap-rocks, oil pools were formed in the tidal channels of LSC1 and gas pools were formed in the sand flats of LSC2.

Key words: Tazhong area, Silurian, Kepingtage Formation, tidal flat sedimentary, high-resolution sequence stratigraphy, oil-gas pool distribution

摘要： 塔里木盆地塔中地区志留系柯坪塔格组为潮控滨岸带沉积环境,主要发育潮坪沉积。在低缓地形背景下发育的柯坪塔格组潮坪沉积环境可分为潮间带和潮下带,发育泥坪、混合坪、砂坪和潮道相沉积。应用高分辨层序地层学原理和方法,把塔中志留系柯坪塔格组分为2个长期旋回(LSC1和LSC2)、5个中期旋回和11个短期旋回层序。在LSC1旋回主要发育潮道沉积,LSC2旋回的沉积相以砂坪为主。对塔中11井、塔中117井的分析发现,潮道和砂坪相带发育了该区的主要储层。泥坪主要集中在LSC1旋回的顶部,形成油藏的良好盖层;LSC2旋回上覆的大套红色泥岩形成了气藏的良好盖层。由于上覆盖层的有效遮挡,在柯坪塔格组的潮道和砂坪中油气聚集成藏,其中在LSC1旋回中形成油藏,在LSC2旋回中形成气藏。

关键词: 塔中地区, 志留系, 柯坪塔格组, 潮坪沉积, 高分辨层序地层学, 油气藏分布