成岩过程中长石和碳酸盐矿物溶蚀机理及其物性响应

发布时间：2018-06-15 22:54

  本文选题：长石 + 碳酸盐矿物　； 参考：《中国石油大学(华东)》2015年博士论文

【摘要】：含油气盆地碎屑岩储层埋藏过程中成岩地质流体及其控制下的矿物溶蚀、溶蚀物质传输及次生矿物沉淀等物理化学作用过程,对储层质量具有重要的改造作用,属于地质学前沿研究。论文综合利用沉积岩石学、实验地球化学、模拟地球化学、石油地质学等多学科交叉方法,系统总结了碎屑岩储层中长石和碳酸盐矿物的(选择性)溶蚀现象和长石溶蚀次生产物的不均匀沉淀现象,厘定了东营凹陷胜坨地区沙三中亚段-沙四段碎屑岩储层和南堡凹陷高柳地区沙三段碎屑岩储层成岩事件及成岩流体演化过程;结合热动力学约束的流体-岩石相互作用模拟实验,提出了胜坨地区相对封闭体系中有机质热演化生成CO_2等酸性流体选择性溶蚀长石(不溶蚀碳酸盐矿物)形成规模性次生孔隙的机理,以及高柳地区相对开放体系中大量大气淡水和有机质热演化生成CO_2等酸性流体共同溶蚀长石和碳酸盐矿物形成规模性次生孔隙的机理。结合长石溶蚀-物质传输-次生矿物沉淀数值模拟实验约束下次生矿物(粘土矿物和石英胶结物)不均匀沉淀的数值模拟实验和实际地质体中长石溶蚀次生孔隙、次生矿物特征,明确了封闭成岩体系和开放成岩体系中矿物溶蚀作用的物性响应和次生矿物的再分配模式。岩石学特征表明,碎屑岩储层中可发育长石弱溶蚀-碳酸盐矿物强沉淀组合(I)、长石强溶蚀-碳酸盐矿物不(弱)溶蚀组合(Ⅱ)、长石强溶蚀-碳酸盐矿物强溶蚀组合(Ⅲ)、长石弱溶蚀-碳酸盐矿物强溶蚀组合(Ⅳ)等4种类型的长石和碳酸盐矿物成岩组合关系,其中组合I和Ⅱ在胜坨地区普遍发育,组合III在高柳地区普遍发育。在碳酸盐胶结作用相对较弱的储层中可发育长石弱溶蚀-少量粘土矿物-少量石英胶结物组合(Ⅰ’)、长石弱溶蚀-大量粘土矿物-少量石英胶结物组合(Ⅱ’)、长石大量溶蚀-大量粘土矿物-大量石英胶结物组合(Ⅲ’)、长石大量溶蚀-大量粘土矿物-少量石英胶结物组合(Ⅳ’)、长石大量溶蚀-少量粘土矿物-少量石英胶结物组合(Ⅴ’)等5种类型的长石溶蚀-次生溶蚀产物成岩组合关系,其中组合Ⅰ’和Ⅲ’在胜坨地区发育,组合Ⅳ’在民丰地区发育,组合Ⅴ’在高柳地区发育,Ⅱ’可见于高柳地区小部分储层。CO_2和CH_3COOH溶解长石和碳酸盐矿物的化学平衡常数和热动力学约束下的水-岩反应数值模拟表明,在钾长石-方解石-酸-H2O体系中,相同温度条件下溶蚀钾长石的化学反应平衡常数大大高于溶解方解石的化学反应平衡常数,同一流体-岩石体系中溶解方解石比溶解钾长石需要更低的pH,造成碳酸盐矿物的溶解对流体规模和侵蚀性具有更强的依赖性,从而在地质时间尺度流体-岩石相互作用过程中发育钾长石溶蚀-方解石不溶蚀(甚至沉淀)的现象。酸浓度和水体积增大促进矿物溶解,离子盐效应促进矿物溶解,同离子效应抑制矿物溶解,钾长石溶蚀生成伊利石比生成高岭石更能促进钾长石的溶解。胜坨地区沙三中亚段-沙四段断裂发育弱,流体超压发育,自生矿物稳定同位素和地层水化学特征表明,储层成岩过程中大气水影响弱,储层具有典型的相对封闭成岩体系。在该体系中,早成岩阶段泥岩中有机质微生物发酵作用为早期碳酸盐胶结物提供碳源,造成胶结物在互层的砂岩层边部大量沉淀,形成长石弱溶蚀-碳酸盐矿物强沉淀组合;中成岩阶段,缺少大气淡水供给,地层内部水体有限,碳酸盐矿物溶解被化学平衡抑制,有机质热脱酸生成大量CO_2和有机酸进入储层并选择性溶蚀长石矿物,形成规模性次生孔隙。高柳地区断裂体系发育,流体超压弱且发育局限,自生矿物稳定同位素和地层水化学特征表明,储层成岩过程中大气淡水影响强烈,储层具有典型的相对开放成岩体系。初始埋藏沉降阶段,随着地层温度的升高,储层中沉淀出较多碳酸盐胶结物;构造抬升阶段和后续埋藏阶段,断裂体系强烈发育使得大量大气淡水下渗到中深部储层,同时在中成岩阶段,有机质热脱酸作用贡献一定量的酸性流体,在大规模水体存在的相对高温条件下,储层中长石和碳酸盐矿物同时发生溶解作用,形成规模性次生孔隙。砂层中注入富CO_2酸性流体时,耦合长石溶解-物质传输-次生矿物沉淀的数值模拟表明,从上游到下游,适当条件下砂层中发育3个区带:溶解带—过渡带—沉淀带。溶解带溶解长石,不沉淀次生矿物;过渡带溶蚀长石,沉淀高岭石;沉淀带溶蚀长石,沉淀高岭石和石英矿物。温度增大、矿物反应速率升高、注入水流速降低及离子浓度增大倾向于缩短溶解带和过渡带;温度降低、矿物反应速率降低、注入水流速增大及离子浓度降低扩展溶解带和过渡带。在断裂体系不发育地层中,近地表低温-高流速砂层倾向于形成矿物组合Ⅴ’,浅层砂层倾向于形成矿物组合Ⅳ’,中深层高温-低流速砂层倾向于形成矿物组合Ⅲ’;断裂的发育增加矿物组合Ⅳ’和Ⅴ’在中深层砂层发育的可能性。在胜坨地区中成岩阶段相对封闭的高温-低流速成岩体系中,碳酸盐胶结物不(弱)溶解,同时长石颗粒溶蚀产物发生准原地沉淀,长石溶蚀次生孔隙为调配型次生孔隙,溶蚀作用未能有效改善储层物性。在高柳地区中成岩阶段大气淡水大量供给的高温-高流速开放成岩体系中,长石和碳酸盐矿物同时被强烈溶解,且长石溶蚀产物被有效带出储层,矿物溶蚀次生孔隙为增孔型次生孔隙,溶蚀作用有效改善物性。
[Abstract]:During the burial process of the clastic rock reservoir in the oil and gas basin, the physical and chemical processes, such as the rock geological fluid and its controlled mineral dissolution, the transport of the dissolved material and the secondary mineral precipitation, have an important transformation effect on the reservoir quality. It belongs to the study of the geological pre-school. The paper combines sedimentary petrology, experimental geochemistry, and simulated earth. Chemical, petroleum geology and other interdisciplinary methods have systematically summarized the phenomenon of (selective) dissolution of feldspar and carbonate minerals in the clastic reservoir and the uneven precipitation of the secondary production of feldspar, determined the debris reservoir of the S3 middle subsection Sha four section of the Shengtuo area of Dongying sag and the three fragment of Sha three section in the high willow area of Nanpu Sag. The formation of rock formation and the evolution process of diagenetic fluid, combined with the simulation experiments of fluid rock interaction with thermal dynamic constraints, proposed the mechanism of the formation of the secondary porosity of the acidic fluid selective corroded feldspar (not dissolved carbonate minerals) in the relative closed system of the Shengtuo region and the formation of CO_2 and other acidic fluids. The thermal evolution of a large number of atmospheric fresh water and organic matter in the relative open system produces the mechanism of the formation of large secondary pores by the common dissolution of feldspar and carbonate minerals by CO_2 and other acidic fluids. The numerical simulation of the dissolution of feldspar - material transfer - secondary mineral precipitation confines the inhomogeneous precipitation of the next mineral (clay minerals and quartz cementation) The numerical simulation experiment and the secondary pore of the feldspar dissolved in the actual geological body and the secondary mineral characteristics clearly define the physical response of the mineral dissolution and the secondary mineral redistribution pattern in the closed diagenesis and the open diagenesis system. The petrological characteristics indicate that the weak dissolution of the feldspar and the carbonate mineral precipitate assemblage can be developed in the clastic reservoir. (I) the combination of feldspar strong dissolution carbonate minerals (II), strong dissolution of feldspar and strong dissolution of carbonate minerals (III), 4 types of feldspar and carbonate mineral assemblages, such as feldspar weak dissolution and strong dissolution of carbonate minerals (IV), the combination of I and II in Shengtuo area, and the combination of III in high willow area. Development. In reservoirs with relatively weak cementation, a weak dissolution of feldspar can be developed - a small amount of clay minerals - a small amount of quartz cementation (I '), weak feldspar dissolution - a large number of clay minerals - a small amount of quartz cementation (II'), massive dissolution of feldspar - A large number of clay minerals - a large number of quartz cementation (III ') and massive dissolving of feldspar. A large amount of clay minerals - a small amount of quartz cementation (IV "), a large amount of feldspar dissolution - a small amount of clay minerals - a small amount of quartz cementation (V") and other 5 types of feldspar dissolution - secondary dissolution product diagenesis, in which combination I 'and III' are bred in Shengtuo area, combination IV is developed in Minfeng Area and combination V 'is high The development of the willow area, II 'can be seen from the chemical equilibrium constant of.CO_2 and CH_3COOH dissolved feldspar and carbonate minerals in the small part of the high willow area and the numerical simulation of water rock reaction under the constraints of thermal dynamics. It is shown that in the potassium feldspar acid -H2O system, the chemical reaction equilibrium constant of the etched potash feldspar is much higher than that in the potassium feldspar acid -H2O system. The chemical reaction equilibrium constant of calcite dissolves, and the dissolving calcite in the same fluid requires a lower pH than the dissolved potassium feldspar, resulting in a stronger dependence of the dissolution of the carbonate minerals on the scale and eroding of the fluid, thus developing the potassium feldspar dissolution in the process of the interaction of the fluid rock phase in the geological time scale. The phenomenon of dissolution (even precipitation). Acid concentration and water volume increase to promote mineral dissolution, ionic salt effect promotes mineral dissolution, and ion effect is used to inhibit mineral dissolution. The dissolution of potassium feldspar can promote the dissolution of potassium feldspar more than the formation of kaolinite in the formation of kaolinite. The fracture of the four segment of the middle Sha 3 middle sand section of Shengtuo area is weak, and the fluid overpressure develops, self The stable isotopes of Mineral Minerals and the chemical characteristics of stratigraphic water indicate that the atmospheric water is weak in the reservoir diagenesis, and the reservoir has a typical relative closed diagenetic system. In this system, the organic matter fermentation of the organic matter in the early diagenetic stage provides carbon source for the early carbonate cementation, resulting in a large number of cementation in the boundary of the interbedded sandstone layers. Precipitation, forming a combination of feldspar weak dissolution and carbonate mineral precipitation; in the middle diagenetic stage, the supply of fresh water is lacking, the water in the stratum is limited, the dissolution of carbonate minerals is suppressed by chemical equilibrium, a large number of CO_2 and organic acids are generated by organic matter and organic acids are formed into the reservoir and selectively dissolved feldspar minerals, forming a large secondary pore. High willow area The fracture system is developed, the fluid overpressure is weak and the development is limited. The stable isotopes of the authigenic minerals and the stratigraphic water chemistry indicate that the reservoir has a strong influence on the atmospheric fresh water during the formation of the reservoir, and the reservoir has a typical relative open diagenetic system. In the stage of uplift and subsequent burial, a large amount of atmospheric fresh water is strongly developed into the middle and deep reservoirs. At the same time, in the middle diagenetic stage, a certain amount of acid fluid is contributed by the thermal deacidification of organic matter. In the relatively high temperature condition of the large-scale water body, the feldspar and carbonate minerals in the reservoirs dissolve at the same time. A large-scale secondary pore is formed. In the sand layer, when the rich CO_2 acid fluid is injected into the sand, the numerical simulation of the coupling feldspar dissolution material transfer and secondary mineral precipitation shows that from upstream to downstream, 3 zones are developed in the sand layer under appropriate conditions: dissolved zone - transition zone - precipitation zone. Dissolved feldspar, no secondary minerals, and transition zone dissolved feldspar. Precipitation of kaolinite; precipitate zone dissolved feldspar, precipitated kaolinite and quartz minerals. The temperature increases, the rate of mineral reaction increases, the velocity of the injection flow decreases and the ion concentration increases to shorten the dissolution zone and the transition zone; the temperature decreases, the mineral reaction rate decreases, the injection flow speed increases and the ion concentration is reduced to the expanded dissolving zone and transition zone. In the undeveloped strata, the near surface low temperature high velocity sand beds tend to form mineral assemblage V ', and the shallow sand beds tend to form mineral assemblage IV', and the middle depth high temperature low velocity sand beds tend to form mineral assemblage III '; the development of fracture growth increases the possibility of mineral assemblage IV and V' in the middle depth sand development. In the relatively closed high temperature and low velocity diagenetic system of the middle diagenetic stage in the Tuo area, the carbonate cements are not (weak) dissolved, while the dissolution products of feldspar particles are quasi situ precipitation, and the secondary pores of the feldspar are secondary pores, and the dissolution can not effectively improve the physical properties of the reservoir. In the high temperature and high velocity open diagenetic system, the feldspar and carbonate minerals are strongly dissolved, and the feldspar dissolution products are effectively taken out of the reservoir, and the secondary pores of the mineral dissolution are the pore type secondary pores, and the dissolution effectively improves the physical properties.
【学位授予单位】：中国石油大学(华东)
【学位级别】：博士
【学位授予年份】：2015
【分类号】：P618.13
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本文编号：2023974