Fault-fracture systems of the Xujiahe tight sandstone in the Northeast Sichuan Basin, Part I: Distribution of fault damage zones
LIAO Zonghu, CHEN Weilun , LI Wei , LIU Hui , ZOU Huayao , HAO Fang
1 College of Geoscience, China University of Petroleum-Beijing, Beijing 102249, China 2 School of Geosciences, China University of Petroleum-Huadong, Tsingdao 266580, China
Fault damage zones are often associated with complex fracture systems that provide important pathways for subsurface fluid migration, affecting oil and gas reservoirs, mineral deposits, groundwater, etc. To date, subsurface fault characterization has been relatively limited due to lack of data. The purpose of this paper is to characterize the planar distribution of the damage zones of the reverse fault systems on top of the Xujiahe tight sandstone in the Malubei area of Tongnan by using three-dimensional seismic attributes. The seismic attributes include, maximum and minimum curvature attributes, seismic variance, and comple mentary amplitude profiles.
The results show that the Tongnanba anticline was subjected to the superimposed effects of several tectonic movements, forming the present-day north-east anticline with a series of secondary north-west folds and fault fragmentation zones. Six NNW-trending fault damage zones were identified in the study area. There are three fault damage zones with lengths >10 km, and three shorter ones with lengths of 3~6 km. Each of the damage zones has a different width of between 270~1250 m, as an important part of the fault-fracture system in the area. The analysis indicates that both Ma101 and Ma201 are in the structural-high parts surrounded by the large faults (F3, F6), with the advantage of a fracture network. The fault F2 may be a source-reservoir pathway and in communication with the lower marine phase, while the other regions lack accumulation potential as they are located far away from faults and in a lower part of the structure. This paper provides a new approach to the identification and depiction of geometrical patterns of subsurface fault damage zones through the analysis of multiple seismic attributes, which is important to the delineation of the subsurface fault-fracture systems and the corresponding accumulation models of natural gas in the Sichuan Basin.
LIAO Zonghu, CHEN Weilun, LI Wei, LIU Hui, ZOU Huayao, HAO Fang. Fault-fracture systems of the Xujiahe tight sandstone in the Northeast Sichuan Basin, Part I: Distribution of fault damage zones. Petroleum Science Bulletin, 2020, 04: 441-448.
