库车坳陷白垩系深层致密砂岩储层溶蚀作用实验模拟研究
- 1. 中国石油杭州地质研究院, 杭州 310023;
- 2. 中国石油集团碳酸盐岩储层重点实验室, 杭州 310023
基金项目:
国家科技重大专项(2016ZX05003-001,2017ZX05001-002)
作者简介:
曾庆鲁,男,1985年出生,硕士,工程师,油气储层地质,E-mail:zengql_hz@petrochina.com.cn
- 收稿日期:
2017-08-07
- 修回日期:
2017-11-09
- 刊出日期:
2018-10-10
摘要: 库车坳陷前陆区白垩系发育特低物性、强非均质性和高稳产砂岩储层,溶蚀作用显著,但成因机制尚不是很明确。利用高温高压热模拟实验还原了目的层在成岩演化过程中1种表生流体和2种埋藏流体环境下溶蚀作用差异,揭示了成岩矿物演化过程及储集空间结构变化特征。结果表明,表生成岩期大气淡水淋滤弱酸性流体环境(CO2饱和溶液,pCO2=1 MPa)溶蚀作用最为显著,长石类矿物发生明显溶蚀,石英和黏土矿物相对难溶,Na+、Ca2+和K+等离子析出明显,Si4+和Al3+析出较少,样品表面沉淀出较多的疑似多边形石英和铝硅酸类矿物;成岩晚期油气充注酸性流体环境(乙酸溶液,2 mL/L)溶蚀作用其次,易于溶解白云石、石膏和长石类矿物,Ca2+、Mg2+、Na+和Si4+等离子析出明显,样品表面无沉淀;成岩早—中期碱性流体环境(NaHCO3溶液,pH=7.46、HCO3-=0.6 mol/L)溶蚀作用相对较弱,石英、长石和部分黏土矿物均发生了不同程度的溶蚀,且随着温度、压力的增加,溶蚀作用程度增加。综合分析表明:表生流体是研究区砂岩储层溶蚀孔隙发育的关键因素,其次为有机酸和碱性埋藏流体。这一认识能够丰富致密砂岩储层孔隙成岩演化理论,为下一步寻找规模储层发育区和气田有效开发提供理论支撑。
Experimental Simulation for Dissolution of Cretaceous Tight Sand Rocks as Deep Reservoir in Kuqa Depression
- 1. PetroChina Hangzhou Research Institute of Geology, Hangzhou 310023, China;
- 2. Key Laboratory of Carbonate Reservoir, CNPC, Hangzhou 310023, China
Funds:
National Science and Technology Major Project, No. 2016ZX05003-001, 2017ZX05001-002
- Received Date:
2017-08-07
- Rev Recd Date:
2017-11-09
- Publish Date:
2018-10-10
Abstract: The sandstone reservoirs in the Kuqa foreland area of Tarim Basin have the characteristics of very low physical properties, strong heterogeneity and high-stable production, in which the dissolution of reservoir rocks is significant, but their formation mechanism is not very clear by far. A series of thermal simulation experiments under high temperature and high pressure were performed to restitute the dissolution effects of target layers in addition of one epidiagenetic fluid and two kinds of burial fluids for a better understanding of the diagenetic process, and then to realize the diagenetic evolution of minerals and spatial changes of reservoir structures. In the epidiagenetic stage, there was weak acidic fluid environments leached by atmospheric fresh water and replaced with saturated CO2 solution (pCO2=1 MPa) in the experiment. The results showed that the dissolution was very significant and feldspar minerals emerged significant dissolution, while the quartz and clay minerals were relatively insoluble. Na+, Ca2+ and K+ were separated out more obviously with Si4+ and Al3+ less. Many suspected polygonal quartz and aluminosilicate minerals have precipitated on the sample surface. The dissolution was secondary in the acidic environment (instead by acetic acid solution, 2 mL/L) formed by hydrocarbons filling in the later diagenetic stage and dolomite, gypsum and feldspar minerals were easily to be dissolved. Ca2+, Mg2+, Na+ and Si4+ were separated out apparently without precipitation. The dissolution is relatively weak in NaHCO3 solution (pH=7.46, HCO3-=0.6 mol/L) which is instead of the alkaline environment of early-middle diagenetic stage and the dissolution of quartz, feldspar and clay minerals appeared in different degrees which increase with the increase of temperatures and pressures. Comprehensive analysis showed that superficial fluid was the key factor for dissolved pore development of sandstone reservoirs in the study area, followed by organic acid and alkaline buried fluid. This understanding not only enriches the theory of porosity and genesis evolution of tight sandstone reservoirs, but also provides theoretical support for the next prospecting of scale reserves and effective development of gas fields.
曾庆鲁, 张荣虎, 王力宝, 赵继龙, 佘敏. 库车坳陷白垩系深层致密砂岩储层溶蚀作用实验模拟研究[J]. 沉积学报, 2018, 36(5): 946-956. doi: 10.14027/j.issn.1000-0550.2018.079
ZENG QingLu, ZHANG RongHu, WANG LiBao, ZHAO JiLong, SHE Min. Experimental Simulation for Dissolution of Cretaceous Tight Sand Rocks as Deep Reservoir in Kuqa Depression[J]. Acta Sedimentologica Sinica, 2018, 36(5): 946-956. doi: 10.14027/j.issn.1000-0550.2018.079
Citation: |
ZENG QingLu, ZHANG RongHu, WANG LiBao, ZHAO JiLong, SHE Min. Experimental Simulation for Dissolution of Cretaceous Tight Sand Rocks as Deep Reservoir in Kuqa Depression[J]. Acta Sedimentologica Sinica, 2018, 36(5): 946-956. doi: 10.14027/j.issn.1000-0550.2018.079
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