酒泉盆地青西凹陷窟窿山构造带下沟组沉积特征及储层预测

Sedimentary characteristics and reservoir prediction of Xiagou Formation in Kulongshan structural belt,Qingxi Sag,Jiuquan Basin

下白垩统下沟组沟零段(K1g0)、沟一段(K1g1)为酒泉盆地青西凹陷窟窿山构造带的主力产层,为明确其沉积特征及有利储层分布,利用岩心、测井、地震及分析化验等资料,开展了高分辨率层序地层划分、物源分析、沉积微相展布研究,阐述了储层特征及主控因素,基于储层综合评价划分了储层类型,并运用深度学习非线性反演技术预测了有利储层分布。结果表明:酒泉盆地青西凹陷窟窿山构造带下沟组K1g0—K1g1自下而上可划分为4个中期基准面旋回(MSC1—MSC4)和8个短期基准面旋回(SSC1—SSC8);窟窿山构造带下沟组K1g0—K1g1以退积型扇三角洲为主,发育西部、南部、东部3个物源,扇三角洲在K1g0和K1g1中下部均发育程度高,展布范围广;裂缝是改善储层物性的重要因素,与次生孔隙共同构成主要的储集空间,可划分为孔隙型储层、孔隙-裂缝型储层和致密型储层。利用深度学习非线性反演技术预测有利储层面积14.7 km2。该研究成果可为窟窿山构造带下白垩统油气勘探提供借鉴。

The K1g1 and K1g0 of Lower Cretaceous Xiagou Formation are the main productive layers in Kulongshan structural belt of Qingxi Sag in Jiuquan Basin.In order to clarify the sedimentary characteristics and favorable reservoir distribution,high-resolution sequence stratigraphic division,provenance analysis and sedimentary microfacies distribution study were carried out by using core,logging,seismic and analysis data,and the reservoir characteristics and main controlling factors were expounded.The favorable reservoir distribution was predicted by using deep learning nonlinear inversion technology.The results show that:The K1g1 and K1g0 of Xiagou Formation in Kulongshan structural belt can be divided into four mid-term base level cycles(MSC1—MSC4)and eight short-term base level cycles(SSC1—SSC8)from bottom to top.The K1g1 and K1g0 of Xiagou Formation in Kulongshan structural belt are dominated by retrogradational fan delta,with three provenances in the west,south,and east.The fan deltas have a high degree of development in the middle and lower parts of K1g1 and K1g0,and have a wide distribution range.Fracture is an important factor to improve the physical properties of the reservoir.Together with secondary pores,it constitutes the main reservoir space,which can be divided into pore type reservoirs,pore-fracture type reservoirs and tight reservoirs.The deep learning nonlinear inversion technology was used to predict the favorable reservoir area of 14.7 km2.The research results can provide reference for Cretaceous oil and gas exploration in Kulongshan structural belt.