天然气资源评价重点参数研究

Study on Key Parameters of Natural Gas Resource Assessment

天然气资源评价重点参数主要包括产气率、运聚系数、区带评价参数与可采系数等4项。首先,通过生物气模拟、不同类型干酪根的产气率模拟实验,建立生物气、煤岩、不同类型泥岩与碳酸盐岩的产气率图版;其次,通过相关分析,建立运聚系数与地质参数的关系模型:运聚系数=0.298-0.00259×烃源岩年龄+0.218×有机碳含量-0.00223×成藏关键时刻-0.00236×盖层厚度+0.0009×盖层埋深-0.286×不整合数+0.000104×储层年龄;第三,在大量统计分析的基础上,建立中国天然气区带地质评价参数体系与取值标准;最后,基于岩性和驱动类型两大因素将天然气藏分为5种类型,其中:碎屑岩水驱气藏的可采系数为50%-70%,碎屑岩气驱气藏75%-90%,碳酸盐岩水骆气藏55%-80%,碳酸盐岩气驱气藏80%-95%,致密气藏40%-55%。

There are mainly 4 key parameters of natural gas resource evaluation, including gas production rate, migration-accumulation coefficient, play evaluation parameters, and recovery rate. First, gas production rate charts of biotic gas, coal, mudstone, and carbonate are built up through biotic gas simulation experiments and pyrolyses. Second, the relationship of migration-accumulation coefficient and different geologic parameters is K = 0. 298 - 0. 00255 + 0. 218C - 0. 002237' - 0. 00236D + 0. 0009H - 0. 2867V + 0. 000104R (K-migration-accumulation coefficient, S-age of source rock, C TOC, T-critical moment, D-thickness of Cap, H-depth of cap, N-times of unconformities, R-age of reservoir rock). Third, play evaluation parameter system and classification standards are built up based on lots of statistics. In the end, recovery rate of 5 types of natural gas reservoirs are analyzed and the results are: recovery rate of gas drive-clastic reservoirs is (75%-90%), water drive-clastic ones 50%-70%, gas drive-carbonate ones 80%-95%, water drive-carbonate ones 55%-80%, and tight ones 40%-55%.