塔西南地区油气成藏主控因素与重点突破方向

Principal controlling factors of oil and gas accumulation and key exploration targets in southwestern Tarim Basin

  • 摘要: 塔里木盆地塔西南地区下寒武统玉尔吐斯组、石炭系卡拉沙依组烃源岩品质佳,古构造格局及断裂活动演化与油气充注关键期适配,储盖配置关系优越;近期多口井获得工业油气流,呈现多层系、多类型立体勘探的局面,但不同层位成藏控制因素及勘探方向具有明显差异性。以逼近寒武系有效烃源岩发育区、聚焦麦盖提斜坡及和田与麦西两大古隆起、主攻三大领域为目标,对塔西南关键层位成藏主控因素及重点突破方向进行了系统研究。麦盖提斜坡寒武系主要目标区包括西段肖尔布拉克组缓坡背景下的颗粒滩(有利面积超过100 km2)、中段玉中地区东段上寒武统阿瓦塔格组前积体、东段玉东—玉中构造带盐下构造—岩性圈闭等。和田古隆起及周缘构造带奥陶系碳酸盐岩领域主要面向生烃坳陷的持续构造运动稳定区、继承性活动断裂带等晚期油气充注的有利目标区;规模储层形成和保存是关键,玉东断褶区6条后展式逆冲推覆构造带及岩溶叠合区、玉中低凸起3条走滑断裂+串珠状强反射的缝洞体叠合区为重点区带,地震上进行了多次波发育情况下小尺度缝洞体成像攻关。麦西古隆起巴什托地区上古生界在海西期之后长期位于构造高部位,寒武系、石炭系双源供烃,油气成藏有利,上倾方向以巴楚组生屑灰岩段高能滩相及东河塘组岩性—构造圈闭为目标,岳普湖区块以小海子组高能滩相有利圈闭为目标,采用保幅保真提高地震分辨率采集处理解释技术系列实现了针对薄层、致密砂岩储层的精准预测。

     

    Abstract: The Lower Cambrian Yuertus Formation and the Carboniferous Kalashayi Formation in the southwestern Tarim Basin have high-quality source rocks. The paleotectonic framework and evolution of fault activity are well aligned with the critical periods of oil and gas charging, and the reservoir-cap configuration is favorable. Recently, multiple wells have achieved industrial oil and gas flows, presenting a multi-layer, multi-type three-dimensional exploration potential. However, significant differences exist in the controlling factors of accumulation and exploration directions among different strata. Focusing on the Cambrian effective source rock development zone, the Maigaiti slope, the Hetian and Maixi peo-uplifts, and three major domains, this study systematically investigated the main controlling factors of oil and gas accumulation and key breakthrough directions in key strata of the southwestern Tarim Basin. The main target areas of the Cambrian in the Maigaiti slope included: (1) grain shoal facies developed under a gentle slope setting of the Xiaoerbulake Formation in the western segment (favorable area exceeding 100 km2); (2) progradational bodies in the Upper Cambrian Awatag Formation in the eastern Yuzhong area of the central segment; and (3) subsalt structural-lithologic traps in the Yudong-Yuzhong structural belt in the eastern segment. For the Ordovician carbonate rock in the Hetian paleo-uplift and its peripheral structural zones, exploration was mainly focused on stable areas of continuous tectonic movement and inherited active fault zones in hydrocarbon-generating depressions, which were favorable target areas for late-stage oil and gas charging. The key challenge was the formation and preservation of large-scale reservoirs. Critical zones included: six break-back thrust nappe structural belts and karst superposition areas in the Yudong fault-fold area, and three strike-slip faults plus fractured-vuggy body superimposed areas with bead-like strong reflections in the Yuzhong low uplift. Seismic imaging of small-scale fractured-vuggy bodies under multiple-wave interference conditions was strengthened. The Upper Paleozoic in the Bashituo area of the Maixi paleo-uplift remained in a structural high position after the Hercynian period and received dual-source supply from the Cambrian and Carboniferous, providing favorable oil and gas accumulation. In the updip direction, targets included high-energy shoal facies of the bioclastic limestone section of the Bachu Formation and the lithologic-structural traps of the Donghetang Formation. In the Yuepuhu block, targets were the favorable traps of the high-energy shoal facies of the Xiaohaizi Formation. A series of acquisition, processing, and interpretation techniques with amplitude preservation and fidelity enhancement for improving seismic resolution were adopted to achieve accurate prediction of thin and tight sandstone reservoirs.

     

/

返回文章
返回