Limitation of fault-sealing and its control on hydrocarbon accumulation——An example from the Laoyemiao Oilfi eld of the Nanpu Sag  

作　　者：Jiang Zhenxue Dong Yuexia Li Hongyi Liu Luofu Liu Guangdi Li Xiaoying 

机构地区：[1]Basin and Reservoir Research Center, China University of Petroleum, Beijing 102249, China [2]State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China [3]Research Institute of Exploration and Development, Jidong Oilfield, PetroChina, Tangshan, Hebei 063004, China [4]School of Resources and Information Technology, China University of Petroleum, Beijing 102249, China

出　　处：《Petroleum Science》2008年第4期295-301,共7页石油科学（英文版）

基　　金：the Key Project of Chinese National Programs for Fundamental Research and Development (973 Program, No. 2006CB202308);the National Natural Science Foundation of China (Grant No. 40472078)

摘　　要：Based on previous studies on the internal structures of fault belts, the fault belts in the Laoyemiao Oilfield of the Nanpu Sag can be divided into three units, a crushed zone, an upper induced fracture zone and a lower induced fracture zone according to the log response characteristics. The upper induced fracture zone is characterized by the development of pervasive fractures and has a poor sealing or non-sealing capability. It therefore can act as pathways for hydrocarbon migration. The lower induced fracture zone consists of fewer fractures and has limited sealing capability. The crushed zone has a good sealing capability comparable to mudstone and can thus prevent lateral migration of fluid. Through physical modeling and comparing laboratory data with calculated data of oil column heights of traps sealed by faults, it is concluded that the fault-sealing capability for oil and gas is limited. When the oil column height reaches a threshold, oil will spill over from the top of reservoir along the lower induced fracture zone under the action of buoyancy, and the size of reservoir will remain unchanged. Analysis of the formation mechanisms of the fault-sealed reservoirs in the Nanpu Sag indicated that the charging sequence of oil and gas in the reservoir was from lower formation to upper formation, with the fault playing an important role in oil and gas accumulation. The hydrocarbon potential in reverse fault-sealed traps is much better than that in the consequent fault-sealed traps. The reverse fault-sealed traps are favorable and preferred exploration targets.Based on previous studies on the internal structures of fault belts, the fault belts in the Laoyemiao Oilfield of the Nanpu Sag can be divided into three units, a crushed zone, an upper induced fracture zone and a lower induced fracture zone according to the log response characteristics. The upper induced fracture zone is characterized by the development of pervasive fractures and has a poor sealing or non-sealing capability. It therefore can act as pathways for hydrocarbon migration. The lower induced fracture zone consists of fewer fractures and has limited sealing capability. The crushed zone has a good sealing capability comparable to mudstone and can thus prevent lateral migration of fluid. Through physical modeling and comparing laboratory data with calculated data of oil column heights of traps sealed by faults, it is concluded that the fault-sealing capability for oil and gas is limited. When the oil column height reaches a threshold, oil will spill over from the top of reservoir along the lower induced fracture zone under the action of buoyancy, and the size of reservoir will remain unchanged. Analysis of the formation mechanisms of the fault-sealed reservoirs in the Nanpu Sag indicated that the charging sequence of oil and gas in the reservoir was from lower formation to upper formation, with the fault playing an important role in oil and gas accumulation. The hydrocarbon potential in reverse fault-sealed traps is much better than that in the consequent fault-sealed traps. The reverse fault-sealed traps are favorable and preferred exploration targets.

关 键 词：Limitation of fault-sealing fault belt oil column height hydrocarbon accumulation Nanpu Sag 

分 类 号：TE65[石油与天然气工程—油气加工工程]