裂缝对沙一段席状砂油藏高产井的控制及其地球物理识别

Fracture Control and Geophysical Identification of High Yield Wells in Sheet Sand Reservoirs in the first member of ShaXimiao

为明确裂缝对沙一段底部席状砂体油藏增产增效的影响,在透析沙一段席状砂体储层特征的基础上,借助岩心、薄片、测井、地震等资料,分析了沙一段席状砂储层成藏的关键因素,并根据高产井测井和地震资料对主控因素进行了地球物理识别,结果表明:(1)席状砂体属于特低孔、特低渗型储层,具有良好横向连续性,储层与非储层互层,非均质性较强;(2)油源一部分来源于凉高山组的油气通过裂缝运移,另一部分来源于大断层沟通凉高山组甚至大安寨段油气,断层与裂缝叠加发育极大改善了储层的渗透性;(3)50 Hz分频相干计算结果显示,沙一底共发育41条断层,以公1井大断层为主,将研究区分为南北两个部分,在公1井大断层的南部发育临近断层的次一级断层或小断层,与主断层在平面上形成斜交组合;(4)基于结构梯度张量的裂缝因子区域内进行定性预测裂缝发育特征显示,在公1井大断层附近裂缝发育外,高产井处的裂缝发育特征更加明显。

The early exploration mainly focused on the comprehensive study of the channel sand body in the middle and lower part of Shaximiao Formation.There is a lack of clear understanding of the reservoir characteristics of the sheet sand body of the bottom shore shallow lake facies and the main controlling factors for the high production of the reservoir.In order to clarify the increase in production and efficiency of fractures on the bottom sheet sand reservoir of Sha-1 member,this paper takes the bottom sheet sand of Sha-1 member of Gongshanmiao structure in central Sichuan as the object,analyzes the key factors for the formation of the sheet sand reservoir of Sha-1 member on the basis of analyzing the reservoir characteristics and hydrocarbon source conditions of the sheet sand body of Sha-1 member with the help of core,thin section,log-ging,seismic and other data,and conducts geophysical identification of the main control factors according to the logging,logging and seismic data of high-yield wells,The results show that:①the sheet sand body belongs to the ultra-low porosity and ultra-low permeability reser-voir.The sand body has the characteristics of good lateral continuity of sand body,interbedding of reservoir and non reservoir(tight layer),and strong heterogeneity;②The oil source of Sha-1 member is partly from the oil and gas of Lianggaoshan Formation through fractures to commu-nicate and migrate,and the other part is from the large fault to communicate Lianggaoshan Formation and even the oil and gas of Daanzhai Mem-ber to migrate to the reservoir in a large scale.The overlapping development of faults and fractures greatly improves the permeability of the reser-voir and can form an effective storage and permeability system;③The calculation result of 50 Hz frequency division coherence shows that 41 faults are developed in Shayi bottom,mainly the big fault of Well Gong 1,and the study is divided into two parts:the north and south.The west of Well Gong 1 and the north and south of the fault do not develop its secondary fault or small fault,while the east of Well Gong 1 mainly devel-ops the secondary fault or small fault adjacent to the fault in the south of the big fault,forming an oblique combination with the main fault on the plane;④Qualitative prediction of fracture development characteristics in the fracture factor area based on structural gradient tensor shows that the fracture development characteristics in high yield wells are more obvious than those near the major fault of Well Gong 1.