Fluid Phase Simulation and Evolution of a Condensate Gas Reservoir in the Tazhong Uplift, Tarim Basin

Abstract

The fluid phase and the evolution of the condensate gas reservoir in the Lianglitage Formation (O3), Well ZG7-5, Tazhong Uplift, were studied by integrating the PVTsim and the PetroMod software. The fluid phase was successfully simulated, and the burial, temperature, pressure, and pressure coefficient histories were reconstructed. The evolution of the fluid phase and its properties (density, viscosity, and gas-oil ratio) under the ideal and gas washing conditions was also explored. The simulated pressure-temperature (P‐T) phase diagram confirms that the reservoir fluid is in the condensate gas phase at present, with an order of critical point-cricondenbar-cricondentherm (CP‐Pm‐Tm). The temperature and pressure show an overall increasing trend considering the entirety of geological evolution. Under ideal conditions, fluid transition from coexisting gas and liquid phases to a single condensate gas phase occurred during the Late Cretaceous (80 Ma, T=135.7°C, and P=58.19 MPa). The density and viscosity of the liquid phase decreased gradually while the density and viscosity of the gas phase and the solution gas-oil ratio increased during geological processes. With the consideration of gas washing, the critical phase transition time points for 100% and 50% gas washing fluid are 394 Ma, 383 Ma, 331 Ma, and 23 Ma, as well as 266 Ma and 23 Ma, respectively. The average liquid phase density, gas phase density, and liquid phase viscosity under 100% gas washing are larger than those under 50% gas washing before 23 Ma (Miocene), while the gas phase viscosity values are similar for both cases. This study visually suggests that the temperature and pressure histories, which are controlled by the burial history and heat flow evolution, and gas washing have significant impacts on the formation of the condensate gas reservoirs and evolution of the fluid phase and its features in the Tazhong Uplift.

Fluid Phase Modeling and Evolution of Complex Reservoirs in the Halahatang Depression of the Tabei Uplift, Tarim Basin

“…To clarify the phase characteristics and differences between the Tazhong and Tabei Uplift, we discussed phase characteristics of the studied typical reservoirs in the Tabei Uplift and differences of typical Ordovician, ZG7–5 (O), and Cambrian reservoirs, ZS1 ( ) and ZS5 ( ), in the Tazhong Uplift by combining our results with the previous works. 18 , 19 The phase diagram containing all reservoirs is displayed in Figure 10 , and concrete data are listed in Table 3 . The phase envelope of the oil and condensate gas reservoirs in the Tazhong Uplift both have a higher pressure range than the same type of studied reservoirs in the Tabei Uplift ( Figure 10 ).…”

“…For a better understanding of the phase behavior of fluids in complex reservoirs of the studied area, the results of this study were compared with the previous results in the Tazhong Uplift. 18,19 This study provides a quantitative way to recover the phase evolution process in complex reservoirs, which has shown guiding significance and scientific value for solving the complexity of oil and gas phase states, and also provides applicability and reference for the study of phase evolution in other areas.…”

Phase Behavior of the Mid-deep Carboniferous Near Critical Condensate Gas Reservoir in Junggar Basin, China

“…As per the SY/T 6285 standard Specification for Gas Condensate Reservoir and the national standard Classification of Natural Gas Reservoirs (GB/T 26979−2011), this reservoir is categorized as exhibiting an extraordinarily high condensate gas output. Typically, condensate gas reservoirs in the region showcase condensate oil content ranging from 100 to 300 g/cm 3 .…”

“…The discovery of the first near-critical condensate gas reservoir in the Junggar Basin, specifically within the mid-deep reservoir of the Carboniferous system at the Luliang uplift, marks a significant advancement in hydrocarbon exploration. , This reservoir, located at a well depth exceeding 5000 m, operates under a pressure (Pr) of 67.89 MPa and temperature (Tr) of 127.1 °C, which presents unique phase characteristics . Notably, (1) the SX well area exhibits favorable physical properties, dual medium characteristics, and a robust liquid supply capacity, contributing to stable production and pressure. , Additionally, (2) the identification of two distinct gas wells in the Junggar Basin, especially the well X, showcases exceptional performance metrics, including a notable “Two high and one low” well test performance, which diverges from typical reservoir behavior in the region .…”

Hydrocarbon Phase State Evolution and Accumulation Process of Ultradeep Permian Reservoirs in Shawan Sag, Junggar Basin, NW China

“…Therefore, it is necessary to restore the physical properties and phase states of hydrocarbons in reservoirs during the main hydrocarbon migration and accumulation periods to study the evolution and mechanism of hydrocarbon migration and accumulation in ultradeep reservoirs. There have been some studies about hydrocarbon phase states and evolution of deep and ultradeep reservoirs with high temperature and high pressure in the Tarim Basin, Sichuan Basin and Upper Yangtze Platform in China. ,− …”