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为了研究碳酸盐岩储层原油裂解过程中硫、钙元素赋存状态的变化,采集塔河油田TK772井奥陶系鹰山组产层的原油,通过半开放实验体系“地层孔隙热压生排烃模拟仪”开展仿真地层条件的成气模拟实验,利用同步辐射X射线吸收近边结物(XANES)技术对固体产物中的硫、钙元素的化学赋存状态进行精确检测。结果表明,原油直接裂解(原油+灰岩实验(系列1))固体产物中含硫化合物以噻吩类和硫酸钙为主,是原油裂解过程中部分噻吩类物质被氧化的结果;含钙化合物以碳酸钙为主。有溶解硫酸盐存在的原油裂解(原油+灰岩+硫酸镁实验(系列2))固体产物中含硫化合物以硫酸钙为主,噻吩类为辅,可能是溶解硫酸盐(硫酸镁)的加入、硫酸盐热化学还原反应(TSR)和溶蚀-沉淀作用共同作用的结果。系列2中伴随着温压的升高,H2S的生成和硫酸钙相对百分含量增加,指示原油裂解过程中发生了硫酸盐热化学还原反应(TSR);硫酸钙的生成和富集表明,TSR过程产生的酸性流体可以对碳酸盐岩储层产生明显的溶蚀作用,同时可能会生成次生膏盐。
In order to study the changes of the occurrence state of sulfur and calcium elements during the cracking process of crude oil in carbonate reservoirs, crude oil from the Yingshan Formation of the Ordovician Yingshan Formation in the TK772 Well of Tahe Oilfield was collected. Through the semi-open experimental system, Hydrocarbon simulator "to carry out simulated formation conditions of gas into the experiment, the use of synchrotron radiation X-ray absorption near edge structures (XANES) technology for solid products in the sulfur and calcium chemical state of occurrence of an accurate detection. The results showed that thiophene and calcium sulfate were the main sulfur compounds in the crude oil cracking (Crude Oil + Limestone Experiment (Series 1)), which was the result of partial oxidation of thiophene in the crude oil cracking process. Calcium carbonate based. Crude cracking with the presence of dissolved sulphate (Crude Oil + Limestone + Magnesium Sulfate Experiment (Series 2)) The sulfur compounds in the solid product are mainly calcium sulphate, with the addition of thiophenes, possibly due to the addition of dissolved sulphate (magnesium sulphate) , Sulphate thermochemical reduction (TSR) and dissolution-sedimentation. In series 2, with the increase of temperature and pressure, the formation of H2S and the relative percentage of calcium sulfate increased, indicating the thermochemical sulfate reduction (TSR) occurred during the cracking of crude oil. The formation and enrichment of calcium sulfate indicated that TSR Acidic fluids generated during the process can cause significant erosion of carbonate reservoirs and secondary gypsum salts may form.