西泉地区石炭系内幕型火山岩储集层特征及成藏模式

Characteristics and Hydrocarbon Accumulation Models of Carboniferous Inside-Type Volcanic Reservoir in Xiquan Area, Junggar Basin

准噶尔盆地东部西泉地区石炭系内幕型火山岩储集层非均质性强,控制因素不明,油气成藏规律不清成为该区勘探的瓶颈。利用物探、地质、钻探等资料,对西泉地区石炭系内幕型火山岩储集层特征进行了研究。研究区内幕型火山岩储集层低孔、低渗、非均质性强,属于裂缝-孔隙型。岩性、岩相是形成优质储集层的基础,裂缝发育程度是影响储集层物性及有效性的重要因素,溶蚀作用能够促进石炭系内幕型火山岩储集层物性的改善。根据烃源岩与储集层的配置关系,构建了研究区石炭系火山岩油气成藏模式,巴塔玛依内山组发育风化壳型油藏;松喀尔苏组发育两类内幕型气藏,即松喀尔苏组b段岩性气藏及松喀尔苏组a段构造气藏。石炭系浅层高勘探程度区为油藏发育区,而深层斜坡带为天然气的有利勘探区,勘探程度低,勘探前景广阔。

The strong heterogeneity, unclear controlling factors and reservoir accumulation rules of the Carboniferous inside-type volcanicreservoir constrain its exploration in Xiquan area of eastern Junggar basin. Based on the data of geophysical prospecting, geology and drill-ing, the paper studies the characteristics of the Carboniferous inside-type volcanic reservoir in Xiquan area. The inside-type volcanic reser-voir in the study area is characterized by low porosity, low permeability and strong heterogeneity, which belongs to fracture-pore reservoirs.The study shows that lithology and lithofacies are the basis for high-quality reservoir forming, the development degree of fractures is an im-portant factor affecting the physical property and effectiveness of the reservoir, and dissolution can improve the physical properties of theCarboniferous inside-type volcanic reservoir. Based on the configuration relationships between hydrocarbon source rocks and reservoirs, 3 hydrocarbon accumulation models of the Carboniferous volcanic rocks in the study area are established—the reservoir of weathering crusttype is mainly developed in Batamayineishan formation; 2 kinds of inside-type gas reservoirs are found in Songkaersu formation, i.e., thelithological gas reservoirs in the b member of Songkaersu formation and the structural oil and gas reservoirs in the a member of Songkaersuformation. The shallow Carboniferous strata with high exploration degree are the areas where oil reservoirs are developed, and the deepslope zones are the favorable areas for natural gas exploration which has good prospecting potential and low exploration degree.