## 2 Geological Setting  
The study block, the Kekeya condensate gas field, is located at the western end of the second tectonic belt on the southern edge of the Yecheng depression in the southwest of the Tarim Basin, at the northern foot of the Kunlun Mountains. It belongs to the Kekeya fold belt and is administratively located within Yecheng County, Xinjiang Uygur Autonomous Region, approximately 50 km south of Yecheng County [26,27] (Figure 1). The main area of the Kekeya condensate gas field features a relatively simple terrain, consisting of a Gobi plain with an elevation ranging from 1830 to 1890 m. To the south, there are sand dunes, and the region experiences a typical continental arid climate. To the west, the structure connects to an anticline with a chessboard-like nose, while to the east, it gradually rises, narrows, and is thrust-covered by the Fushakriyong tectonic belt. The structure is a short-axis anticline, with a slightly steeper northern wing and a slightly gentler southern wing, nearly symmetrical in shape. Except for the outcropping Tertiary strata in the axial part, the surface is mostly covered by Quaternary strata. The Kekeya structure has undergone tectonic movements during the late Hercynian, Indosnian, and Yanshan periods. The structural prototype began to take shape in the late Miocene Kiziloy period and early Anjuan period. The late Pliocene to Quaternary was the formation and large-scale development period of the anticline trap, and from the late Oligocene to the late Miocene, the Kekeya area continued to rise and become structurally defined [28,29]. The Kekeya structure was discovered in 1956, and drilling began on 1 May 1976. On 17 May 1977, Well Kekeya\(-1\) produced a high-yield oil and gas flow, leading to the discovery of the Kekeya condensate gas field. As of 17 May 2022, the Kekeya condensate gas field has cumulatively produced 5.188 million tons of crude oil and 12.41 billion cubic meters of natural gas, with an oil and gas equivalent of 15.07 million tons. Figure 1: Regional tectonic setting of the Kekeya Gas-Condensate Field (after PetroChina Tarim Oilfield Company). In the reservoir of the study area, the primary types of reservoir space are primary porosity, secondary porosity, and microfractures. The porosity types are mainly intergranular porosity and intragranular porosity, with good connectivity. The average permeability is 19.4 \(\times\) 10\({}^{-3}\)\(\upmu\)m\({}^{2}\), classifying it as a low-to-medium permeability reservoir. The distribution of the reservoir is uneven in the plane, controlled by sedimentary facies and lithology, with better connectivity in the north-south direction and poorer connectivity in the east-west direction. The study area developed thick layers of continental clastic rocks, with the Miocene to Pliocene clastic deposits gradually becoming coarser, indicating a tectonic uplift of the basin's source area. The sediment thickness of the Miocene Xihepu Formation reflects the area's rapid subsidence rate and abundant sediment supply, indicative of its paleogeographic characteristics. There are significant lithological differences between the study area and the central depression, mainly characterized by the absence of thick gravel facies, and instead, red fine sandstones, siltstones, and sandstone mudstones dominate. Medium\(-\) to coarse-grained sandstones and gravels appear only as interlayers. The sedimentary characteristics suggest that during the deposition of the Miocene, the depositional water energy in the area was relatively weak [30; 31; 32; 33]. Currently, due to the long-term depletion-style development of the oil and gas field, formation pressure has decreased, resulting in a decline in production capacity, which poses significant challenges for subsequent development. Early on, due to insufficient production data, there was a lack of understanding regarding the distribution characteristics of the sand bodies and the reservoir's extent.