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松辽盆地南部长岭断陷下白垩统致密砂岩天然气勘探开发不断有新的发现,显示出较大的勘探开发潜力。研究下白垩统登娄库组与泉一段物源、沉积相、沉积体系展布规律对天然气富集区带评价及开发具有重要的意义。利用重矿物、砂岩碎屑成分及地震剖面等资料确定长岭断陷登娄库组和泉头组一段沉积时期主物源方向为西南及南部,以发育辫状河及辫状河三角洲相为主,同时,还发育冲积扇、扇三角洲和湖泊相。登娄库组沉积早期,发育多个被低凸起分隔的次断凹,在断凹陡坡带发育扇三角洲,缓坡带发育辫状河—辫状河三角洲沉积体系,沉积体系分散于各断凹内,且互不影响;登娄库组沉积后期,长岭断陷性质由断陷向坳陷转换,断凹相互连通,沉积中心趋于一致,来自多个物源的辫状河—辫状河三角洲沉积体系,向沉积中心推进。泉一段沉积时期,长岭断陷整体沉降,沉积中心北移,至此完成了由断陷向坳陷的转化,辫状河在宽缓的地形上广泛发育,河道砂体具有广覆式大面积分布的特征。前期勘探揭示,辫状河道相互叠置形成的厚砂层,是主要的储集体类型,结合沉积体系展布特征,评价优选出2个主要有利区带:①登娄库组上部辫状河与辫状河三角洲平原相带,主体分布于长岭断陷南部哈尔金—西西里嘎与双坨子—老爷府低凸起带;②泉一段底部辫状河道叠置带,在长岭断陷南部广泛分布。
The exploration and development of the tight sandstone of the Lower Cretaceous in the Changling fault depression, southern Songliao Basin continue to have new discoveries, showing great exploration and development potential. It is of great significance to study the distribution of provenances, sedimentary facies and depositional systems in the Upper Cretaceous Denglouku Group and Quanquan for the evaluation and development of natural gas enrichment zones. Based on the data of heavy minerals, sandstone detrital components and seismic profiles, the main source of sedimentary period of Denglouku Formation and Quantou Formation in Changling fault depression is southwest and southern, and the braided river and braided delta are dominant At the same time, alluvial fans, fan delta and lakes are also developed. In the early depositional period of Denglouku Formation, there were a number of sub-depressions separated by low protuberances, fan delta in steep fault zone, and braided river-braided river delta depositional system in gentle slope belt. Sedimentary system was dispersed in various depressions During the depositional period of Dengloukuang Formation, the nature of Changling fault changed from fault depression to depression, and the fractures and valleys became interconnected and the sedimentary centers tended to be consistent. Braided river-braided River Delta sedimentary system, to the sedimentary center. During the depositional period of the spring, the Changling Fault Deposition as a whole settled down and the sedimentary center moved northward, thus completing the transformation from the fault depression to the depression. The braided river developed extensively on the wide terrain, and the channel sand body has a large area Distribution characteristics. The early exploration revealed that the thick sand layers formed by overlapping braided channels are the main types of reservoirs. Based on the distribution characteristics of sedimentary system, two main favorable zones were selected for evaluation: ① upper braided river of Denglouku Formation and Braided delta facies belt, the main body is located in the southern part of Changling fault Haerjin-Xisiliga and Shuangtuozi-Laoyefu low uplift belt; (2) Wide distribution.