元坝大安寨灰岩-砂岩-页岩储集模式及开发对策

Accumulation Mode and Development Countermeasures for Limestone-Sandstone-Shale Reservoirs in Daanzhai Member,Yuanba Block

为探究川东北地区元坝区块大安寨段致密介屑灰岩-砂岩-页岩混合沉积储集体的分布特征与组合模式,利用岩心分析、测井解释、地质综合研究与编图等手段,分析目标区混合沉积体系下发育的各类储集体类型与测井响应特征,建立表征储集体分布特征的纵横向组合模式与平面叠合模式,探讨研究区天然气的开发潜力与开发策略。研究结果表明:元坝区块大安寨段为一套包括介壳滩、浅湖泥、坝砂和滩砂的混合沉积体系,同时发育测井响应特征明显、数量不等、强非均质分布的致密灰岩、砂岩和页岩储集体;在纵横向与平面上分别识别出5类灰岩-砂岩-页岩储集体组合模式与叠合模式,不同类别的储集体组合具备不同的天然气资源潜力;优化水平井钻井和水平井分段压裂技术组合与工艺流程是川东北地区元坝区块大安寨段灰岩-砂岩-页岩储集模式得以成功开发的关键。该研究结果对同类地区的开发具有一定的借鉴意义。

In order to investigate the distribution characteristics and combination patterns of the dense clast limestone-sandstone-shale mixed sedimentary reservoirs in Daanzhai Member,Yuanba Block,northeast Sichuan,the types of reservoirs and logging response characteristics of various reservoirs developed under the mixed sedimentary system in the target area were analyzed by means of core analysis,well logging interpretation,comprehensive geological study and mapping,the vertical and horizontal combination model and plane superposition model were established to characterize the distribution characteristics of the reservoirs,and the development potential and measures of natural gas in the study area were discussed.It was found in the study that Daanzhai Member in Yuanba Block is a mixed sedimentary system comprising ostracum beach,shallow lake mud,dam sand and beach sand,accompanied by the development of dense limestone,sandstone and shale reservoirs with distinct logging response characteristics,unequal quantity and strongly non-homogeneous distribution;five types of limestone-sandstone-shale reservoir assemblages and coincidence modes were identified in the longitudinal and transverse directions and planes respectively;the different reservoir assemblages had different gas resource potential;the key to the successful development of the limestone-sandstone-shale reservoir mode in Daanzhai Member,Yuanba block in northeast Sichuan was to optimize the technical combination and process flow of horizontal well drilling and staged fracturing.The results of this study can be used as a reference for the development of similar areas.