Title: Formation and evolution of concealed fault zone in sedimentary basin and its reservoir-controlling effect

Authors: Weiwei Zhou; Weifeng Wang; Chenchen Shan; Guangzeng Wang

Addresses: School of Geosciences in China, University of Petroleum, Qingdao, 266580, Shandong Province, China ' School of Geosciences in China, University of Petroleum, Qingdao, 266580, Shandong Province, China ' School of Geosciences in China, University of Petroleum, Qingdao, 266580, Shandong Province, China ' School of Geosciences in China, University of Petroleum, Qingdao, 266580, Shandong Province, China

Abstract: Concealed fault zones are a type of weak deformation fault zones that form in sedimentary covers and have expressive forms. This paper introduces an effective way to identify such structures according to the distributions of reservoirs, sedimentary facies, sub-sags (or sags) and salients (or ridges), and classified concealed fault zones into five types according to their scales, i.e., trap-scale, sub-sag-scale, sag-scale, depression-scale and basin-scale and characterised their structural features. Concealed fault zones go through five consecutive evolutionary stages, from the initiation of induced fractures (R shears), to the development of localised en echelon faults (R fault), to the appearance of discontinuous main faults (Y faults), to interconnected Y faults that accommodate the strike slips of basal faults, and finally to a through-going revealed strike-slip fault. Case studies show that oil-gas reservoirs often distribute as en echelon, string- or band-like features in concealed fault zones, so they might be promising oil-gas exploration targets in the future. [Received: June 29, 2015; Accepted: September 8, 2015]

Keywords: concealed fault zones; basal faults; analogue modelling; reactivation; strike-slip faults; fault zone formation; sedimentary basins; reservoir control; reservoir distributions; sedimentary facies; sub-sags; sags; salients; ridges; oil-gas reservoirs; oil exploration targets; gas exploration targets.

DOI: 10.1504/IJOGCT.2016.077315

International Journal of Oil, Gas and Coal Technology, 2016 Vol.12 No.4, pp.335 - 358

Received: 06 Jul 2015
Accepted: 08 Sep 2015
Published online: 28 Jun 2016 *

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