粘土矿物产状和微结构对地层损害的影响

对120块岩样XRD、SEM分析结果表明,下二门油田纵向粘土矿物演化规律明显,浅、上层系以蒙皂石—高岭石组合为主,中、下层系为绿泥石—高岭石—伊/蒙间层组合,深层系为绿泥石—伊利石组合。发育七种粘土微结构类型,地层微粒的稳定性由占主导地位的微结构类型决定。微结构稳定性序列为层流状>绒球状>畴状>叠片支架状>絮团状>蜂窝状>支架状。预测碱敏、水敏、盐敏和出砂是最严重的地层损害方式。

Influence of Clay Minerals Occurrences and Microstructures on Formation Damage

The experimental data from 120 samples for XRD and SEM analysis show that in Xiaermen Oil Field, clay evolut from shallow to deep with apparent characters. The clay minerals groups in the shallow-upper, Middle-lower, and deep layers are smectite-kaolinite, chlorite - kaolinite -interlayered I/S, and chlorite-illite respectively. Seven types of clay minerals microstructures have been described. The study on these clay minerals microstructures displays that the stability of formation is determined by the dominated types of microstructure in the reservoirs. The order of microstructure stability (from strong to poor) is as following lamina, cabbage, domain, book house, pseudo sphere, honeycomb and cardhouse. Predictions based on comprehensive analysis of sensitive minerals, pore structures, formation fluids and core flow tests indicate that the most serious factors of formation damage are alkaline, fresh water and salted water sensitivity, as well as sand production.