The Geological Characteristics of Reservoirs and Major Controlling Factors of Hydrocarbon Accumulation in the Ordovician of Tazhong Area, Tarim Basin

Abstract

The ancient deep-buried marine carbonate reservoir takes on strong heterogeneity and fluid complexity, and features large acreage and low abundance. For the ancient deep carbonate exploration in China now, it is challenging to find accumulating positions with high abundance and deploy high-efficiency wells. Based on the E&D practices of Ordovician carbonate reservoir and the high-efficiency well correlation in the Tazhong area, Tarim Basin, it is found that the high-efficiency wells distribute along the peaks of third-order structure zone and the relative high parts of platform, about 0.3-1.5km away from the strike-slip fault, and longitudinally, mainly in large unfilled Ordovician fracture-cavity reservoirs in the lower O 1 y 1 , the lower O 1 y 2 and the O 3 l 3. The large scale unfilled fracture-cave system (as favorable reservoir space), the strike-slip fault (as pathway for efficient hydrocarbon charge in late stage) and the sufficient hydrocarbons (charged intensively in multi-stages) contribute to the high abundance hydrocarbon enrichment in the Ordovician karst carbonate reservoir across the Tazhong area. This research recommends to use precise structure interpretation and palaeogeomorphic and palaeotectonic reconstruction to identify the gas source faults and favorable charging position, use precise fracture-cavity description to assess the cavity quantitatively, and use seismic wave impedance inversion and hydrocarbon detection to predict the distribution of large unfilled cavity reservoirs, in order to effectively estimate the high-abundant oil/gas area, locate the high-efficiency well area and improve the E&D performance in ancient deep carbonate rocks.

Geology and Hydrocarbon Accumulation of the Large Ultra-Deep Rewapu Oilfield in Tarim Basin, China

“…As a matter of fact, hydrocarbon preservation's lower temperature limit and effective reservoir burial depth's lower limit may vary largely due to different basin properties, or maybe these lower limits refer to a wide depth range (Zhu et al, 2006;Ma et al, 2007), and we can not give a definite answer by now. In addition, mutual complement between burial time and burial depth is crucial as well (Zhu et al, 2012a;2013a), which may exert great influence on the lower depth limit and result in complexity and diversification of deeplayer fluid phases (Zhang et al, 2011c;Yang et al, 2014;Wang et al, 2013;Zhu et al, 2011a;2013b;Chen et al, 2012). Tarim Basin marine deposit combination was developed mainly in the Paleozoic era, and it has undergone polycyclic superimposition and reconstruction, leading to its complicated oil and gas distribution (Yang et al, 2011;Zhu et al, 2013c;2013d).…”

Formation and distribution characteristics of Proterozoic–Lower Paleozoic marine giant oil and gas fields worldwide

“…The multiperiod tectonic movements resulted in the uplift and erosion of strata, forming large unconformities and providing conditions for the formation of weathering crust karst reservoirs. For example, the multiperiod tectonic movements in the PLP marine strata in the Tarim, Sichuan, East Siberian, and Permian basins produced large-scale karst reservoirs (Postnikova et al 2002;Dutton et al 2005;Kang 2008;Zhang et al 2007b;Luo et al 2008;Liu et al 2010;Zhao et al 2012b;Wang et al 2013b;Zhou 2013;Du et al 2014;Yang et al 2014). S o u t h a n d C e n t r a l O m a n S a lt B a s in E a s t e r n F l a n k Fig.…”

Studies on thermal maturity and hydrocarbon potential of lignites of Bikaner–Nagaur basin, Rajasthan

“…Hydrocarbon resource of a basin is related to source rock, depositional, and tectonic structures and thermal maturation of the organic matter (Yang et al, 2014;Zhu et al, 2015). Contributions have been made by Demaison (1980), Dembicki et al (1983), Mishra and Cook (1992), Peters (1986), Singh and Singh (1998), and Teichmuller and Durand (1983).…”

“…With progress in the coalification, not only the rank changes, but there is also change in the chemical composition and properties of the macerals. Hydrocarbon resource of a basin is related to source rock, depositional, and tectonic structures and thermal maturation of the organic matter (Yang et al., 2014; Zhu et al., 2015). Contributions have been made by Demaison (1980), Dembicki et al.…”