深埋藏环境下的白云岩溶解-沉淀机制

In recent years, deep and ultra-deep dolomite reservoir has shown great potential in petroleum exploration. However, the prerequisite in prediction of high quality deep ultra-deep dolomite reservoirs lays on the mechanism of dolomite dissolution/precipitation. In this study, we proposed to conduct dissolution-precipitation simulation experiments on the deep-ultra deep dolomite samples from Tarim basin under deep burial environments (semi-open and closed systems). The effects of temperature, pressure, dissolved ions (calcium, magnesium, etc.) and pH on the dolomite dissolution-precipitation process will be investigated under high temperature and high pressure (~200ºC; ~70Mpa) with a series of petrographic and geochemical analytical methods. In addition to the growth characteristics and microstructure of most recent drilling cores, we aim to identify the fluid environments of dissolution/precipitation on dolomite reservoirs, and build the geological model for the development of high quality dolomite reservoirs in deep burial environment. Our study will provide basic theory in predicting high quality reservoirs.

近年来的油气勘探实践表明深层-超深层白云岩具有良好的勘探潜力，深埋藏环境下白云岩的溶解-沉淀机制是制约深层-超深层白云岩优质储层预测的关键科学问题。本项目以塔里木盆地深层-超深层白云岩为研究对象，利用岩相学和地球化学相结合的分析手段，开展深埋藏环境(间歇开放环境/封闭环境)溶蚀-沉淀模拟实验，查明高温高压条件下(~200ºC; ~70Mpa)温度、压力、溶液离子(钙、镁离子等)、pH等对白云石溶解-沉淀过程的影响，结合最新钻井岩心白云岩储层发育特征和微观结构，明确深埋藏环境下白云岩储层溶蚀改造/沉淀致密化的流体环境，建立深埋藏环境下优质白云岩储层发育的模式，为深层-超深层白云岩储层预测提供理论基础。

为明确深埋藏环境中白云岩溶蚀-沉淀机制，查明深埋藏环境下白云岩储层溶蚀改造/沉淀致密化的流体环境，建立深埋藏环境下优质白云岩储层发育的模式，项目组经过三年研究，研发了仿真地质环境的高温高压溶蚀模拟实验装置，开展了模拟高温高压地质流体环境的白云岩溶解-沉淀实验及数值模拟计算；分别选取典型井塔深1井、顺南501井寒武系白云岩储层为典型实例，观察其岩心并开展了系统的白云岩沉积与成岩作用分析；结合实验和典型实例解剖分析了不同类型地质流体参与白云岩储层形成过程，揭示“镁离子-硫酸根离子络合”促进白云岩成储，指出受温度控制的溶蚀窗内易于成储，明确了在中-深层埋藏过程中烃源岩热演化过程中伴生的有机酸、CO2能够促进碳酸盐岩成储。成果及时应用于塔里木盆地勘探选区之中，支撑了风险井部署。现已发表论文6篇(SCI 1篇，EI 2篇)，国际会议论文1篇，申请发明专利3件；参与组织碳酸盐岩储层学术研讨会1次（其中，国际学术研讨会一次），大型学术培训一次，共200余人次。