唐佳阳，唐胜利

(1.西安科技大学地质与环境学院，煤炭绿色开采地质研究院，西安 710054；2.中煤西安设计工程有限责任公司，西安 710054)

Single Well Numerical Simulation of Middle JurassicYan’an Formation Coal No.2 Buried,Thermal and Hydrocarbon Generation History Evolution Process in Coalmine No.1,Huangling Mining Area

Tang Jiayang1，2, Tang Shengli1

1.College of Geology and Environment, Xi’an University of Science and Technology, Xi’an 710054;2.China Coal Xi’an Design Engineering Co., Ltd. Xi’an 710054)

Abstract：To study coal measures source rock hydrocarbon generation and expulsion stages, hydrocarbon generation potential and coalbed methane reservoiring evolution features have to carry out recovery simulation study on coal seam “three histories” (i.e. buried history, thermal evolution history and hydrocarbon generation history) evolution process. According to strata lithologic characters, residual strata buried depths today, porosity and vitrinite reflectance etc data or geological information, using PetroMod 1D simulation software carried out reestablishment of “three histories” evolution process in the coalmine No.1, Huangling mining area. The result has shown that the Jurassic coal-bearing strata in the coalmine belong to “early stage subsidence, later stage uplift” type, and experienced two “subsidence-uplift” stages. The first “subsidence-uplift” stage happened during middle Jurassic up to Paleocene, buried depth of coal measures strata fast increasing first (up to the end of Jurassic), then tardily increasing (up to the end of Cretaceous), with maximum depth 1576m, during Paleocene, crust uplift and denuded 190m; during middle Jurassic to earlier early Cretaceous, coal and rock heating temperature and vitrinite reflectance “tardily first then fast and then tardily” increasing. Up to the end of Cretaceous, differential differentiation had been happed, coal No.2 bottom coal and rock heating temperature 79℃～126℃,vitrinite reflectance from 0.50% evolved to 0.70%, coal No.2 top coal and rock heating temperature 78℃～108℃, vitrinite reflectance from 0.50% evolved to 0.67%; during Paleocene, coal and rock heating temperature lowering down, coalification stopped. The second “subsidence-uplift” stage happened during Eocene up to present,coal measures strata subsidence 100m first,then happened maximum uplift under 85.4m/Ma

rate, coal heating temperature further lowering down up to present 22℃. Coal organic matter pyrogenic decomposition hydrocarbon generation (thermogenic gas) has stopped, but microbiological deterioration organic matter hydrocarbon generation (secondary biogenic gas) is underway.

Keywords：buried history; thermal history; hydrocarbon generation history; Yan’an Formation; Huangling mining area

0 引言

成煤原始物质经泥炭化和煤化作用过程可演化为不同变质程度的煤岩并在不同演化阶段生成不同成因类型的煤层气[1]。研究含煤地层在不同地质历史时期的埋藏史、受热演化史和成熟史(简称 “三史”)，可为揭示煤系气的成因机制、成藏条件及成藏动力学系统提供理论依据。国内外学者通过对剥蚀量的恢复计算及地质演化过程的数值模拟技术，研究了不同含煤盆地的构造-埋藏演化过程[2-4]。例如，韩载华[2]采用声波时差和镜质组反射率两种方法对西湖凹陷8口井三个主要剥蚀面上的剥蚀量进行计算，并对不同次级构造单元的埋藏史进行恢复，认为该地区剥蚀厚度小于500m，其中中央反转构造带剥蚀量最大；李兴伟[3]通过Petromod 1D软件对松辽盆地北部大庆长垣地区埋藏史和热演化史和生烃史进行了模拟，认为该区埋藏过程为“两升三降”型，并且青一段烃源岩在明水末期埋深最大，已达排烃门限，为成藏关键时期；罗寿兵等人[4]通过地层回剥技术，结合地层接触关系、构造运动期次、钻井地层厚度和岩性资料的分析，得到5种不同地质意义的沉降类型，并认为四川复合型前陆盆地的沉降机制主要为挠曲负载，即由于造山带载荷与沉积载荷不同导致了自晚三叠世以来两次大的沉降量。因此，针对不同地区开展主要目的层的“三史”地质演化过程研究可为分析盆地形成机制、烃源岩生排烃阶段及油气资源潜力评价提供基础信息[5-6]。……