西湖凹陷孔雀亭地区复合圈闭发育模式与油气富集差异控制因素

The model of compound traps development and controlling factors of hydrocarbon enrichment in Kongqueting area of the Xihu Sag

  • 摘要: 随着勘探程度不断加深,东海西湖凹陷保俶斜坡带全面进入了断层-岩性复合油气藏勘探阶段,位于保俶斜坡中北部的孔雀亭地区是复合油气藏有利发育区。通过对孔雀亭地区复合圈闭发育的构造沉积背景、断裂-古地貌的控砂作用以及分带、分层系油气成藏富集规律研究,明确了孔雀亭地区复合圈闭形成条件、发育模式及油气富集差异控制因素。认为孔雀亭地区西高东低的地貌背景、西部古隆起上发育的多条“U”型及“V”型沟谷,NE向断裂坡折及NW挠曲坡折共同控制了多条水系的平面发育特征及砂体展布,与NE向断层匹配形成了典型的断层-岩性复合圈闭,成为孔雀亭地区重要的勘探领域,取得了断层-岩性圈闭勘探突破。孔雀亭地区不同区带油气富集程度不同,圈闭与有效烃源岩距离、砂体规模、储层物性、断层封堵性等要素的匹配程度控制各带油气富集程度。中低带相对近源,断层未断至浅层,保存条件好,受断坡及挠曲坡折共控,为规模砂体卸载区,物性较好,油气相对最为富集,具有良好的勘探潜力。

     

    Abstract: With the advancement of exploration degree, the western slope belt of the Xihu Sag in the East China Sea has fully entered the stage of fault-lithologic compound reservoir exploration. The Kongqueting area, located in the north-central part of the western slope belt, is a favorable area for compound reservoirs. We specified the formation conditions, the development patterns, and the controlling factors of differential enrichment of hydrocarbon in compound reservoir of the study area by studying on the structure and sedimentary settings, the controlling effect of faults and paleogeomorphology on sand distribution, and hydrocarbon accumulation and enrichment rule in different zones and formations. In geomorphology, it was high in the west and low in the east in the study area. It developed multiple U- and V-shaped valleys on the ancient uplifts in the west of the study area, the ancestral rivers and the sand distribution were controlled by the north-east faulted slope-break and the north-west flexural slope-break. The north-west sand bodies matches the north-east faults, and formed the fault-lithological compound traps, which has become an important field for exploration and expansion of reserves in the study area, and achieved a breakthrough in fault-lithological reservoir exploration. The degree of hydrocarbon enrichment is different in Konqueting area, and is controlled by the distance between trap and source, the size of sand body, the fault plugging capacity, and their combinations. The middle and low Kongqueting area has the highest degree of hydrocarbon enrichment and the best expansion potential because of the proximity to source rock, the best storage condition, the large sand body, and the good reservoir properties.

     

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