Oil & Gas Geology ›› 2022, Vol. 43 ›› Issue (6): 1397-1412.doi: 10.11743/ogg20220610

• Petroleum Geology • Previous Articles     Next Articles

Sequence architecture, sedimentary evolution and controlling factors of the Permian Shan-1 Member, Qingyang gas field, southwestern Ordos Basin

Hui Xia1,2(), Long Wang1,2, Daofeng Zhang1,2, Jiping Wang1,2, Qianqian Fan1,2, Min Feng1,2, Yan Wang1,2   

  1. 1.Exploration and Development Research Institute, PetroChina Changqing Oilfield Company, Xi'an, Shaanxi 710018, China
    2.National Engineering Laboratory of Low-permeability Oil & Gas Exploration and Development, Xi'an, Shaanxi 710018, China
  • Received:2022-04-10 Revised:2022-09-22 Online:2022-11-21 Published:2022-11-21

Abstract:

The Qingyang gas field in the Ordos Basin is the most promising for reserve growth and production addition, with the first member of Permian Shanxi Formation (Shan-1) being the main pay zone. However, a lack of understanding to the sedimentary evolution and controlling factors of the member hinders further exploration and development of the field. A systematic study was then carried out on the development and evolution of sedimentary sequences of the member as well as its response to palaeogeomorphology, paleocurrent and lake level changes based on analyses of 3D seismic, logging, core and test data through logging wavelet transform, INPEFA and Fischer plots. The results show that the member contains a third-order sequence of a full transgressive-regressive cycle. The sequence can be further divided into the low stand, transgressive and high stand system tracts. Depositional systems are recognized to be shallow-water deltas and lacustrine systems. Fischer plots reveal that the lacustrine level change during deposition of the member experienced a rapid transgression to a slow regression, accompanied by the secondary lake-level fluctuation. The stacking succession recording PA (progradation to accretion) to R (retrogradation) then to AP (accretion to progradation) corresponds to the migration and evolution of sedimentary facies and the changes in accommodation space. The delta sandstone reservoirs, widely developed in ancient landform slope area during the low stand system tracts, are considered the potential targets for exploration and development of gas in the field.

Key words: lake level fluctuation, sequence architecture, sedimentary evolution, Shanxi Formation, Qingyang gas field, Ordos Basin

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