Sedimentary facies and lithologic characters as main factors controlling hydrocarbon accumulation and their critical conditions  

作　　者：Jun-Qing Chen Xiong-Qi Pang Dong-Xia Chen 

机构地区：[1]State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum(Beijing) [2]Basin and Reservoir Research Center, China University of Petroleum (Beijing) [3]Unconventional Natural Gas Institute, China University of Petroleum (Beijing)

出　　处：《Journal of Palaeogeography》2015年第4期414-432,共19页古地理学报（英文版）

基　　金：supported by the National Basic Research Program of China(Grant No:2011CB201100);China National Natural Science Foundation Program(Grant No.41402107)

摘　　要：Taking more than 1000 clastic hydrocarbon reservoirs of Bohai Bay Basin, Tarim Basin and Junggar Basin, China as examples, the paper has studied the main controlling factors of hydrocarbon reservoirs and their critical conditions to reveal the hydrocarbon distribution and to optimize the search for favorable targets. The results indicated that the various sedimentary facies and lithologic characters control the critical conditions of hydrocarbon accumulation, which shows that hydrocarbon is distributed mainly in sedimentary facies formed under conditions of a long lasting and relatively strong hydrodynamic environment; 95% of the hydrocarbon reservoirs and reserves in the three basins is distributed in siltstones, fine sandstones, conglomerates and pebble-bearing sandstones; moreover, the probability of discovering conventional hydrocarbon reservoirs decreases with the grain size of the clastic rocks. The main reason is that the low relative porosity and permeability of fine-grained reservoirs, lead to small differences in capillary force compared with surrounding rocks and insufficiency of dynamic force for hydrocarbon accumulation; the critical condition for hydrocarbon entering reservoir is that the interfacial potential in the surrounding rock（ Un） must be more than twice of that in the reservoir（ Us）; the probability of hydrocarbon reservoirs distribution decreases in cases where the hydrodynamic force is too high or too low and when the rocks have too coarse or too fine grains.Taking more than 1000 clastic hydrocarbon reservoirs of Bohai Bay Basin, Tarim Basin and Junggar Basin, China as examples, the paper has studied the main controlling factors of hydrocarbon reservoirs and their critical conditions to reveal the hydrocarbon distribution and to optimize the search for favorable targets. The results indicated that the various sedimentary facies and lithologic characters control the critical conditions of hydrocarbon accumulation, which shows that hydrocarbon is distributed mainly in sedimentary facies formed under conditions of a long lasting and relatively strong hydrodynamic environment; 95% of the hydrocarbon reservoirs and reserves in the three basins is distributed in siltstones, fine sandstones, conglomerates and pebble-bearing sandstones; moreover, the probability of discovering conventional hydrocarbon reservoirs decreases with the grain size of the clastic rocks. The main reason is that the low relative porosity and permeability of fine-grained reservoirs, lead to small differences in capillary force compared with surrounding rocks and insufficiency of dynamic force for hydrocarbon accumulation; the critical condition for hydrocarbon entering reservoir is that the interfacial potential in the surrounding rock（ Un） must be more than twice of that in the reservoir（ Us）; the probability of hydrocarbon reservoirs distribution decreases in cases where the hydrodynamic force is too high or too low and when the rocks have too coarse or too fine grains.

关 键 词：sedimentary facies lithologic characters hydrocarbon accumulation hydrocarbon threshold hydrocarbon exploration 

分 类 号：P618.13[天文地球—矿床学]