Experiment of Carbonate Dissolution: Implication for High Quality Carbonate Reservoir Formation in Deep and Ultradeep Basins

Abstract

As the most frontiers in petroleum geology, the study of dissolution-based rock formation in deep carbonate reservoirs provides insight into pore development mechanism of petroleum reservoir space, while predicting reservoir distribution in deep-ultradeep layers. In this study, we conducted dissolution-precipitation experiments simulating surface to deep burial environments (open and semiopen systems). The effects of temperature, pressure, and dissolved ions on carbonate dissolution-precipitation were investigated under high temperature and pressure (∼200 ∘ C; ∼70 Mpa) with a series of petrographic and geochemical analytical methods. The results showed that the window-shape dissolution curve appeared in 75∼150 ∘ C in the open system and 120∼175 ∘ C in the semiopen system. Furthermore, the dissolution weight loss of carbonate rocks in the open system was higher than that of semiopen system, making it more favorable for gaining porosity. The type of fluid and rock largely determines the reservoir quality. In the open system, the dissolution weight loss of calcite was higher than that of dolomite with 0.3% CO 2 as the reaction fluid. In the semiopen system, the weight loss from dolomitic limestone prevailed with 0.3% CO 2 as the reaction fluid. Our study could provide theoretical basis for the prediction of high quality carbonate reservoirs in deep and ultradeep layers.

A study on reservoir architecture difference of extra-deep strike-slip fault zone in the Shunbei area, Tarim Basin

“…Therefore, the faults are right-lateral left stepover obliquely distributed, and compressional uplifts are mainly developed in the overlapping section of faults. While, at the T 7 4 interface, the S-1 fault zone is under the background of tension torsion tectonic stress, the faults are left-lateral left stepover obliquely distributed as the consequence. In the faults overlapping section, pull-apart and drop-offs are mainly developed.…”

“…At the early stage of the evolution of the S-5 strike-slip fault zone, the structural characteristics of a single strike-slip fault match to the Riedel shear model. In episode in the middle Caledonian period, a right-lateral left stepover strike-slip fault zone was developed on the T 7 4 interface, indicating that it was affected by NE direction compressive stress at the stage. The segmentation deformation characteristics of the S-5 strike-slip fault zone are caused by the local stress differences near the fault and the superposition of multi-stage faults.…”

“…Due to the increasing di culty of exploration and development of conventional oil and gas reservoirs worldwide, unconventional reservoirs have attracted intensive attention (Zou et al, 2014;He et al, 2017).…”

A study on reservoir space type of Ordovician ultra-deep marine carbonate reservoir in T-Sh Oilfield, Tarim basin

“…Due to the increasing di culty of exploration and development of conventional oil and gas reservoirs worldwide, unconventional reservoirs have attracted increasing attention (Zou et al, 2014;He et al, 2017). The Tarim Basin, which is situated in the Xinjiang Uygur Autonomous Region of the People's Republic of China, is host to the T-Sh oil eld.…”

Comparative Study on the Reservoir Characteristics and Development Technologies of Two Typical Karst Weathering-Crust Carbonate Gas Reservoirs in China

“…It is one of the main gas fields in Changqing gas area. As for the Sinian gas reservoir in the Anyue gas field, Sichuan Basin, it is a monolithic weathering-crust carbonate rock gas reservoir with the oldest payzone, the most complex gas reservoir characteristics, and largest GIIP in China [9,10]. Currently, it is reported that GIIP of this gas reservoir amounts to trillions of cubic meters, and the gas field is building its production capacity.…”