Structure characteristics and major controlling factors of platform margin microbial reef reservoirs: A case study of Xiaoerbulak Formation, Lower Cambrian, Aksu area, Tarim Basin, NW China

Architecture and paleogeography of the Early Paleozoic carbonate systems in the east-central Tarim Basin (China): Constraints from seismic and well data

“…Well TS1 crossing this seismic facies and outcrop observations reveal the presence of algae-dominated microbial limestones/dolostones (Cambrian and Early Ordovician, Fig. 3K; Bai et al, 2017aBai et al, , 2017b and receptaculitids or calathium (Middle Ordovician, Fig. 3J; Gu et al, 2009), indicating high-energy condition.…”

“…5D, 6D, 7D, 8D and 9D). Subsurface well data are poor to characterize the seismic facies, but coeval outcrops and cores data west of the study area document the presence of dolarenites interbedded with algal dolostones, indicating inner and middle ramp environment (Zhao et al, 2011;Bai et al, 2017a), corresponding in the seismic profile to SF3 (Fig. 4).…”

“…Further constraints about the facies types and distribution (Liu et al, 2003;Gu et al, 2005;Bai et al, 2017aBai et al, , 2017b are provided by outcrops of Cambrian and Ordovician successions (exposed mostly along the western border of the Tarim Basin).…”

“…The Middle-Upper Cambrian rimmed platform is dominated by algal dolostones interbedded with dolarenites. Microbial buildups and shoals characterize the platform margin (Liu et al, 2016;Bai et al, 2017a). Slope facies of the rimmed platforms in the Early Ordovician consist of laminated dolostones and limestones interbedded with grainstones.…”

“…These platforms host numerous gas reservoirs (Jia, 1997), a fact that makes the understanding of the evolution of these carbonate systems critical for hydrocarbon exploration. Numerous previous studies about the overall Tarim carbonates focused on the stratigraphy and paleogeography (Zhao et al, 2010;Lin et al, 2011;Zhao et al, 2011;Chen et al, 2015), depositional architectures of platforms and platform evolution (Gao et al, 2006;Fan et al, 2007Fan et al, , 2008Gu et al, 2009;Wang et al, 2011a;Zhao et al, 2014;Gao and Fan, 2015;Ni et al, 2015;He et al, 2017), the growth mode and characteristics of reef buildups (Xiao et al, 1996;Liu et al, 2003;Gu et al, 2005;Bai et al, 2017aBai et al, , 2017b and controlling parameters, including tectonics, subsidence, eustasy, climate/temperature, salinity and nutrients supply (Zhang et al 2014;Zhao et al, 2014;Liu et al, 2016;He et al, 2017;Zhang, 2017). 20 seismic profiles and 13 selected wells were considered to further detail the evolution of the Cambrian and Ordovician carbonate successions in east-central Tarim Basin, in order to reconstruct the evolution of the depositional systems through time and facies distribution, as well as to identify the role of post-depositional tectonics on the present-day geometry recorded in the seismic profiles.…”