塔里木盆地高温高压条件下奥陶系碳酸盐岩溶蚀机理实验研究

It had experienced a multi-stage, various types of Paleokarst transformation of The Tarim Basin carbonate karst reservoir, both the karstification of geological history in the near-surface environment, and through the superposition and transformation of karstification during burial; the reservoir types are mainly fractured, holes, cracks - holes and caves type. Buried karst of Ordovician carbonate dissolution and filling is constantly buried transformation role. Due to the subsidence of the basin, and the early karst is mainly sedimentary filling.The deep hydrothermal formed corrosion holes characterized by layered. The study is based on high-temperature and high-pressure reaction environment Institute of Karst Geology, Chinese Academy of Geological Sciences. The study, based on the instrument CJ(K) magnetic drive reactor in Institute of Karst Geology, Chinese Academy of Geological Sciences to create a high pressure reactor environment, use of karst formation conditions and Mechanism of Action technology, means of geochemical analysis and microscopic karst research techniques, in order to simulate Tarim Basin deep Ordovician carbonate dissolution mechanism under different temperatures, different pressures, different water chemistry characteristics, and different hydrodynamic conditions, and to study the dissolution morphology and structure characteristics. Mastered the different underground environment palaeokarst mechanism has important theoretical and practical significance.in guiding Tarim Basin Ordovician carbonate rocks, deep oil and gas exploration and development and finding new reserves blocks.

塔里木盆地碳酸盐岩岩溶储层经历了多期次、多种类型的古岩溶作用与改造，既有地质历史时期近地表环境下的岩溶作用，又经历了埋藏过程中岩溶作用的叠加与改造；其储层类型主要为裂缝型、孔洞型、裂缝-孔洞型及洞穴型。埋藏岩溶为奥陶系碳酸盐岩被不断埋藏后所产生的溶蚀和充填改造作用。由于盆地的沉降，早期岩溶以沉积充填为主；同时深部热液作用形成了以层状分布为特征的溶蚀孔洞。本次研究基于中国地质科学院岩溶地质研究所仪器CJ(K)磁力驱动反应釜创造高温高压反应环境，运用岩溶形成条件与作用机理研究技术、地球化学分析手段及微观岩溶研究技术，以此来模拟研究塔里木盆地深部环境下奥陶系碳酸盐岩在不同温度、不同压力、不同水化学特征、及不同水动力条件下的溶蚀机理，并研究溶蚀形态及结构特征。掌握地下不同环境古岩溶作用机制，对指导塔里木盆地奥陶系深部碳酸盐岩油气勘探和开发、寻找新的后备储量区块有着重要的理论和实践意义。

基于磁力驱动反应釜创造高温高压反应环境，通过对塔北露头区奥陶系碳酸盐岩野外古岩溶的调查、取样与建模，结合井下奥陶系碳酸盐岩钻井岩芯古岩溶缝洞系统描述与刻画，分析井下古岩溶识别标识，建立井下古岩溶结构模式，进而揭示井下深部奥陶系碳酸盐岩古岩溶发育规律。. 在野外露头岩溶和井下岩芯岩溶研究基础上开展室内高温高压溶蚀模拟试验50余组。结果表明在温度达到沸点100℃之前，灰岩、白云岩的溶蚀速率随着温度的增加而增大，超过100℃之后，灰岩、白云岩的溶蚀速率随着温度的增大而相对减小；外界环境不变的条件下，灰岩的溶蚀速率大于白云岩，而当温度达到150℃时，灰岩和白云岩的溶蚀速率相当。且在温度、搅拌速度及反应时间均不变的情况下，碳酸盐岩的溶蚀速率随着二氧化碳分压的增加而增大。. 在外界环境影响溶蚀作用的同时，岩石的化学成分和内部结构同样决定着碳酸盐岩溶蚀速率的大小。碳酸盐岩酸不溶物含量越高，溶蚀量就越小。其内部微缝合线和微方解石细脉等细微结构的存在与否，均影响着溶蚀速率的大小。结合高温高压溶蚀试验反应前后水溶液的化学成分对比分析，建立了高温高压岩溶作用模式。该实验成果很好的解释了塔里木盆地哈拉哈塘油田、麦盖提斜坡，及英买力等油田区块在埋深5000~6000m的蓬莱坝组白云岩中同样发育着优质储层的原因。本次研究，为进一步开展碳酸盐岩深埋藏过程中及深埋藏条件下岩溶期的溶蚀机理提供技术条件，为我国深部碳酸盐岩岩溶储层研究提供理论支撑。