【作者】 王伟；

【导师】 胡明毅；

【作者基本信息】 长江大学 ， 矿产普查与勘探， 2014， 硕士

【摘要】 碳酸盐岩礁滩作为有利的油气储集单元往往可以形成大型—特大型油气田。近年来,随着人们对四川盆地二叠系长兴组生物礁滩储集层的勘探程度逐步提高,在见天坝、盘龙洞、黄莲峡,元坝等地区先后发现了生物礁滩,长兴组生物礁越来越受到人们的关注。川东—鄂西地区己发现的二叠纪长兴期生物礁点(露头及井下)共30余处。其中建南地区钻井资料揭示了建南北生物礁、建南南生物滩的存在,具体的分布规律和发现新的礁滩储层有待进一步的研究与探索,因此开展建南地区二叠统长兴组碳酸盐岩生物礁滩分布规律的研究,精细刻画建南地区生物礁滩储层发育特征,预测落实新的礁滩储层分布区,不仅具有重要理论意义,更具实践意义。本论文以碳酸盐岩层序地层学、沉积学、储层地质学、测井地质学和地震沉积学为指导,以野外剖面实测和钻井岩芯的精细观察描述为基础,充分利用岩石薄片、录井、测井、地震以及分析测试资料,采用宏微观相结合和地质理论与地震技术相结合的研究方法,对研究区长兴组礁滩储层特征进行了研究,主要取得了以下几点认识：(1)根据野外剖面和钻井岩芯的精细观察,结合地震资料和关键的层序界面长兴组划分为两个Ⅱ型三级层序,即Sql和Sq2,其中Sql对应于长一段,Sq2对应于长二段,每个层序均发育完整的海侵体系域(TST)和高位体系域(HST)。长兴组与下伏龙潭组以整合接触、与上覆飞仙关组为不整合接触,厚度一般为65-362m。生物礁滩主要发育于两个层序的高位体系域。(2)根据区域沉积特征,确定研究区长兴组存在两种沉积模式：“缓坡模式”和“台地模式”。长兴组以后者模式为主体,可进一步划分出陆棚、台地前缘斜坡、台地边缘礁滩和开阔台地等4种沉积相类型,以及台内滩、台缘滩、台缘礁等若干沉积微相,沉积物以(含)生屑灰岩(云岩)、礁灰岩(云岩)、颗粒灰岩(云岩)和晶粒灰岩(云岩)为主；其中台地边缘相是最有利于储层形成与演化的沉积相带。(3)通过大量岩芯观察和薄片鉴定分析,研究区礁滩储层储集岩类主要为礁云岩、颗粒云岩、晶粒云岩,其次为颗粒灰岩和礁灰岩。储集空间类型主要为粒内溶孔、粒间溶孔、晶间孔、晶间溶孔等,局部微裂缝发育,属于次生孔隙为主的裂缝-孔隙型储层。物性资料分析表明长兴组表现为低孔中低渗储层,物性参数中孔隙度与渗透率呈正相关关系。其中白云岩储集物性普遍好于灰岩。通过各种压汞物性参数分析,认为研究区储层喉道以微、中喉为主；储层物性与孔喉均值、分选系数、歪度呈一定的相关性。(4)研究认为长兴组礁滩储层的发育严格受岩石类型、沉积微相、相对海平面变化和成岩作用的控制。礁灰(云)岩、颗粒云岩为储层主要岩石类型；台缘礁滩相为最有利储层发育的相带,其次为滩间；储层主要发育于相对海平面下降时期；成岩作用明显改造储层物性特征,其中压实-压溶作用、重结晶作用、胶结作用为破坏性成岩作用,溶解作用、白云石化作用和破裂作用为建设性成岩作用：溶解作用促进了孔隙的进一步发育与扩大；几乎所有储层岩石均发育了白云石化作用,提高了白云石的含量；破裂作用对改善储层的物性起到了关键作用。目前研究区长兴组处于晚成岩阶段,储层孔隙度普遍较低。(5)在地质研究的基础上,开展地震研究,通过优选出的地震波阻抗反演方法,指出有利的储层发育区。预测表明：长二段白云岩发育时期,储层主要分布范围为工区中部箭竹溪生物礁滩体部位,建431井区以及西部临溪场部位。长二段礁滩发育时期,储层范围则为中部箭竹溪,中南部金竹坪,以及北部古地貌高部位,临溪场生物礁以及建47局部高部位。在波阻抗反演的基础上通过选取门槛值计算预测出相应的储层厚度,厚度大的部位主要为中部箭竹溪,北部暴露滩体以及西部临溪场生物礁体部位,其储层厚度分布范围符合沉积相展布规律。(6)在以上研究的基础上,对建南地区进行了有利储集区带预测,综合长兴组礁滩分布图、白云岩厚度图、储层预测厚度分布图、储层孔隙度预测平面图等单因素图件进行了综合叠合分析,最终确定长兴组储层的有利区带,分别预测出Ⅰ、Ⅱ、Ⅲ类储层发育区,其中Ⅰ类为最有利储层发育区带。更多还原

【Abstract】 As favorable reservoirs, Carbonate reef and bank can form giant and supergiant field. In recent years, Along with the rising of the exploration degree of the Permian Changxing formation reef-bank reservoir in Sichuan basin, organic reef and bank has been found in successively in Jiantianba, Panlongdong, Huanglianxia, Yuanba and other regions, and Changxing reef has been paid more and more attention. There are more than30points of organic reef (including outcrops and downholes) in eastern Sichuan and western Hubei. The drilling data of Jiannan area reveals the existence of reef in northern Jiannan and bank in southern Jiannan. The distribution and new reef-bank reservoirs needs further research and exploration. Therefore, carrying out research on the distribution of Changxing formation of the Permian reef-bank reservoir in Jiannan area, precisely depicting the developing characteristics of reef-bank reservoir, as well as predicting and locating distribution area of new reef-bank reservoir has both important theoretical and practical significance.In this paper, following basic theories of carbonate sequence stratigraphy, sedimentology, reservoir geology, logging geology and seismic sedimentology, based on fine observation of outcrops and cores, combining with rock slice, logging, seismic and testing data, we carry on study on Changxing formation reef-bank reservoir by methods of combination of macro and micro facies and combination of geological theory and seismic technology. And several conclusions have been made:1.Based on the observation of outcrops and cores, combing with seismic data, two types of sequence boundaries were recognized, and Changing formation was divided into two third-order sequences. Sql was corresponding to first member, Sq2corresponding to the second member, of which transgressive systems tract (TST) and highstand systems tract (HST) were developed. Changxing formation was in unconformity with and the underlying Longtan formation and the overlying Feixianguan formation, of which thickness is180-340m. Reef and bank were mainly developed in HST.2.According to the sedimentary characteristics of the Changxing formation, there are two kinds of depositional models:"ramp model" and "platform model". The sedimentary pattern of Changxing formation is mainly the latter, which can be furtherly divided into4types of sedimentary facies:continental shelf, platform margin slope, platform margin reef and open platform, and interplatform bank, as well as several microfacies:platform bank, platform margin bank (reef), etc. The deposits are mainly bioclastic limestones (or dolostones), reef limestones, grain limestones (or dolostones) and the grain limestones (or dolostones). And the platform margin facies is the most favorable formation and evolution sedimentary facies belt of reservoir.3.According to much fine observation of core and rock slice, reef dolostones, grain dolostones, crystalline grain dolostones, and bioclast limestones were identified as main rock types of reservoir. Reservoir space was composed of intergranular dissolved pore, intragranular dissolved pore, intercrystalline pore, intercrystalline dissolved pore and fracture. Physical property data shows reservoirs in Changxing formation belongs to low-porosity and low-permeability reservoirs, physical property of dolostone is generally better than that of limestone. Through various mercury physical parameters analysis, reservoir throats in the study area are identified as micro and medium throat mainly; and reservoir properties has some correlation with the average pore-throat size, sorting coefficient and skewness.4.The development of reef and bank reservoir is strictly controlled by sedimentary microfacies, rock type, sea-level changes and diagenesis. Reef and bank is the most favourable sedimentary microfacies; hermatolith and grain dolostones are the main rock types; reef and bank are developed at the stage of sea level falling; the formation of reservoir is modified by diagenesis, in which destructive diagenesis include compaction, recrystallization and cementation, constructive diagenesis being dolomitization, dissolution and cataclasis. Almost all rocks of reservoir were dolomitized, physical property were improved by dissolution and cataclasis. Therefore, reservoir of Changxing formation with low porosity is at late diagenetic stage.5.Based on the geological study and seismic research, favorable reservoir development area were recognized by optimizing proper method of impedance inversion. It indicates that reservoirs were mainly distributed in the reef-bank of Jianzhuxi in the middle of study area, including well Jian431area and western Linxichang, while dolostones of the second member deposited. And when reef-bank developed, reservoirs were mainly distributed in the middle of Jianzhuxi, central-southern Jinzhuping, the high position of paleogeomorphology in north, Linxichang organic reef and partial high position of well Jian47area. Reservoir thickness is calculated by selecting threshold value of acoustic impedance inversion body. The result shows that middle Jianzhuxi, northern exposed beach and eastern Linxichang organic reef have bigger reservoir thickness. The distribution of reservoir thickness is highly in accordance with the distribution regularities of sedimentary facies.6.On the basis of these studies, we make predictions of favorable reservoir zone of Jiannan area. By making a comprehensive analysis of Changxing formation reef distribution, dolomite reservoir thickness map, dolomite reservoir thickness distribution forecast maps and other single factor, and taking into account of the development of reservoir properties and structure-sensitive position, the favorable zones for the Changxing formation reservoir is finally determined. We predicte class I, II and IE reservoir development zones, among which the class I is the most favorable reservoir development zone.更多还原