Sedimentary Facies Controls for Reservoir Quality Prediction of Lower Shihezi Member-1 of the Hangjinqi Area, Ordos Basin

: The tight gas reserves in the Hangjinqi area are estimated at 700 × 109 m 3 . Since the exploration of the Hangjinqi, numerous wells are already drilled. However, the Hangjinqi remains an exploration area and has yet to become a gas field. Identifying a paleo-depositional framework such as braided channels is beneficial for exploration and production companies. Further, braided channels pose drilling risks and must be properly identified prior to drilling. Henceforth, based on the significance of paleochannels, this study is focused on addressing the depositional framework and sedimentary facies of the first member (P 2 x 1 ) of the lower Shihezi formation (LSF) for reservoir quality prediction. Geological modeling, seismic attributes, and petrophysical modeling using cores, logs, interval velocities, and 3D seismic data are employed. Geological modeling is conducted through structural maps, thickness map, and sand-ratio map, which show that the northeastern region is uplifted compared to northwestern and southern regions. The sand-ratio map showed that sand is accumulated in most of the regions within member-1. Interval velocities are incorporated to calibrate the acoustic impedance differences of mudstone and sandstone lithologies, suggesting that amplitude reflection is reliable and amplitude-dependent seismic attributes can be employed. The Root Mean Square (RMS) attribute confirmed the presence of thick-bedded braided channels. The results of cores and logging also confirmed the presence of braided channels and channel-bars. The test results of wells J34 and J72 shows that the reservoir quality within member-1 of LSF is favorable for gas production within the Hangjinqi area.


Introduction
Tight sandstone can be defined as a potential reservoir with permeability less than 1 mD or 0.1 × 10 -3 μm 2 and porosity less than 12% [1]. As per contemporary reports of 2019, hydrocarbon shares more than 58% of the world's energy consumption [2]. To suffice the energy needs, tight sandstone gas is presently the leading unconventional natural gas source globally and has developed into a vital parameter for natural gas production [3]. In China, unconventional tight gas provides the most contribution of the unconventional resources and accounts for 39.2% reserves and 24.6% annual production of the total natural gas [3]. Therefore, many geoscientists are working on the reservoir quality prediction of sandstone reservoirs [4][5][6][7]. The Ordos basin (OB) is one of the most productive basins with the highest annual gas output in China [8,9]. The OB has the largest number of gas fields in China. These gas fields include Jingbian, Daniudi, Yulin, Zizhou, Wushenqi, Shenmu, Mizhi, and Sulige [10,11]. The Hangjinqi area lies at the northern OB, situated amid the Yimeng uplift and Yishan slope [12] (Figure 1b). Many exploratory wells have been drilled within the Hangjinqi area, and a substantial volume of gas in the upper Paleozoic sandstones has been found [13,14]. The Hangjinqi has the potential to become a significant gas exploration zone [15].  [9]), (b) Major tectonic units of OB (modified after [9]), (c) 3D seismic grid and wells incorporated in our study.
In the last few decades, geoscientists have emphasized quantitative methods for seismic interpretation because these can provide enhanced information regarding reservoir characterization and reservoir quality prediction [16,17]. Geological modeling is an advanced and essential tool for understanding the depositional framework of sedimentary systems. Geological modeling can be defined as the spatial depiction of surfaces to showcase variations, topography, relief of rocks corresponding to historical geological events. These spatial surfaces are modeled as isochronous surfaces interpolated over the full domain space [18]. Seismic attributes have developed into an advanced and essential tool in most hydrocarbon and developments projects because of their high resolution and high success rate [19][20][21]. The faults distribution deliver imperative evidence associated with tectonics, overpressure, burial history, and diagenesis [18,22,23]. Formation evaluations are widely used to interpret the lithology, porosity, permeability, water saturation, matrix volume, and shale content [24][25][26].
Limited studies have identified reservoir characterization, and most studies highlighted the reservoir diagenesis of the lower Shihezi formation (LSF) (P2x) [1]. The main issues in studying the sedimentary depositional pattern within the Hangjinqi area are as follows; (a) the presence of coal layers beneath LSF [15], (b) uplifting in the Paleozoic causes several lateral variations which were further triggered during the Yanshan structural movements [27]. Former studies conducted on the Hangjinqi area were focused on the evaluation of genetic types and source of upper Paleozoic tight gas [12], hydrothermal mineralization of uranium deposits [28], evaluation of clay mineral content, and type of reservoir properties [8], channel identification within second member and the third member of the LSF [15], structural evolution [11,29], and tectonic controls [30]. We focused on the identification of depositional framework and sedimentary facies controls to evaluate the reservoir quality prediction within the first member (P2x 1 ) of the LSF (P2x) by utilizing the cores, logs, velocities, and 3D seismic data ( Figure 1c). The presented study will showcase important insights related to favorable zones of sand deposition of the lower Shihezi member-1, that can be exploited for future studies.

Geology of the Study Area
The evolution of the OB is the consequence of the interaction among the Paleo-Asian Ocean and North China Block (NCB) (Figure 1a). The OB was formed in the western margin of the NCB during the Paleozoic. The OB was uplifted during the late Cretaceous and converted to a Plateau [28]. However, the OB was separated from the NCB during the Cenozoic, which resulted in six tectonic regions at the top of the Archean-Proterozoic basement [30][31][32][33][34]. The six tectonic units include Weibei uplift, Yimeng uplift, Western thrust belt, Jinxi flexural belt, Yishan slope, and Tianhuan depression [30,35]. The Hangjinqi region is positioned at the Yishan ramp and Yimeng uplift intersection. The Hangjinqi area is considered a favorable area for hydrocarbon migration due to the development of the paleo-high in the northern OB [36]. From the west to the east region of the study area, three main faults are disseminated, among which Porjianghaizi fault (P-fault) (also referred as Boerjianghaizi fault in the literature) is the largest fault that separates the Hangjinqi area into the north and south regions [30] (Figure 1b).
The petroleum play of the study area includes the source rocks of Taiyuan (C3t) and Shanxi (P1s) formations of Carboniferous and lower Permian, which consists of numerous layers of coal bed seams (CBM) and thick beds of mudstones. The main reservoir within the Hangjinqi area consists of the LSF (P2x) of the middle Permian. The LSF (P2x) consists of three members. These members are categorized as a first member (P2x 1 ), second member (P2x 2 ), and third member (P2x 3 ) [30] (Figure 2). The tight sandstones of the LSF having low porosity and low permeability act as the main reservoir, comprising coarse-grained pebbly sandstone, coarse-to-fine sandstones, sandy conglomerate and mudstones layers [15,37]. The thick-bedded mudstones of upper Shihezi (P2s) and Shiqianfeng (P3s) formations act as the main seal rocks [12].

Materials and Methods
The database incorporated in our study consist of 3D seismic, cores, well logs, and interval velocities. The seismic grid of 2500 km 2 and 62 wells are included to observe the depositional framework on a regional scale within the Hangjinqi area. Several geophysical logs from wells J34, J52, J72, such as gamma-ray (GR), spontaneous potential (SP), deep resistivity (LLD), shallow resistivity (LLS), caliper (CAL), and sonic (DT) are incorporated [37,38]. The interval velocities from well J72 are included to identify the acoustic impedance differences among lithologies of the member-1 of the LSF. The core samples from wells J34, J72 and J91, including coarse-grained pebbly sandstone, coarse-to-fine sandstones, sandy conglomerate and mudstones layers, are utilized in our study. The test results of wells J34 from north, J52 from the center, and J72 from southern region were utilized to evaluate the reservoir quality prediction through formation evaluation.
Initially, cores of wells J34, J72 and J91 are incorporated in the study to observe rock type characteristics and sedimentary features such as bedding, grading, sorting, shape, color, and lithologies to identify the facies, subfacies, and microfacies. In the second part, a synthetic seismogram is made using seismic and well log data to interpret the targeted horizons within the member-1 of the LSF. Our study focuses on the first member of the LSF, which lies between the T9d and T9e horizons. T9d was marked at the top of the Shanxi Formation (P1s), while T9e was marked at the lower boundary of the second member (P2x 2 ) of the LSF (Figure 2). Faults distributed within targeted horizons of T9d and T9e are interpreted to identify the impact of tectonic activity. Geological modeling and seismic attribute methods are performed to interpret the reservoir quality prediction. Geological modeling is an effective tool to identify the distribution of sedimentary facies. The geoscientists are constantly evolving geological modeling methods for enhanced prediction of subsurface depositional systems [39,40]. Structural and thickness maps are employed to delineate the topography and thickness distribution of sediments.
For decades, geoscientists have employed seismic attribute analysis to classify sedimentary facies [41][42][43]. Seismic attributes provide valuable, reliable information regarding bed thickness, continuity, fractures, porosity, lithofacies, and sequence boundaries [44]. Interval velocities of well J72 are incorporated to differentiate the sandstone and mudstone lithologies. Later, the Root Mean Square (RMS) attribute is extracted for the lower Shihezi member-1 to identify the geometry of the fluvial braided channels.
In the end, a depositional facies map was produced to show the depositional framework using integrated analysis of structural maps, thickness map, fault distribution maps, sand-ratio map, and horizon RMS attribute map. The reservoir quality is studied through petrophysical analysis using wells J34, J52 and J72 via interpretation of the perforation intervals at reservoir depths of member-1 of the LSF in the Hangjinqi area, northern OB, China.

Description and Interpretation of Drilling Cores and Well-Logging
The fluvial paleo-environments are characterized by porous and permeable coarsegrained sediments such as sandy conglomerate and coarse-grained pebbly sandstone that deposit in the braided channels and establish good quality reservoirs [45]. The sandstone in the braided channels generally exhibit the characteristics of erosional base, good sorting, sub-angular grains, graded bedding and trough cross-bedding [46]. Thin beds of pebbly-sandstone and sandy conglomerate are usually developed at the bottom shows braided bars or channel-bars [47].
The available geological cores of wells J72, J34 and J91 from the member-1 of the LSF are incorporated to identify the characteristics of the microfacies. The core of well J72 at depths of 2943. .55 m shows the presence of a sandy conglomerate having massive bedding ( Figure 3a). A 0.08 m mudstone present in the upper part of the core of well J72 at depths of 2943.55-2943.75 m is in abrupt contact with underlying coarse-grained pebbly sandstone having erosional surface ( Figure 3b). The core of well J72 at depths of 2944.86-2944.97 m, shows the presence of a conglomerate in the lower part, having lithological interface of conglomerate to fine sandstone discontinuity ( Figure 3c). The core of J34 at depths of 2340.84-2340.96 m shows the presence of a light gray coarse-grained pebbly sandstone which is intermixed with gray-white oil traces that is composed of quartz gravel and mud gravel. The coarse-grained gravel sandstone sediments are uneven, disorderly distributed, and locally enriched. The sediments are sub-angular and have medium sorting ( Figure 3d). The core of J34 at depths of 2341.90-2342.06 m shows light gray thick-bedded coarse sandstone, mainly composed of quartz, followed by rock debris and a small amount of feldspar and mica. The sediments are sub-angular, have good sorting with relatively loose argillaceous cementation (Figure 3e). The core of well J91 at depths of 2953. 19-2953.28 m shows the presence of a gray brown mudstone (Figure 3f). The core of well J91 at depths of 2981.08-2981.30 m shows the presence of a light gray medium sandstone. Further, an argillaceous stripe with oblique bedding can also be seen in the middle part of the core surface, and several argillaceous stripes with horizontal bedding are also present in the lower part indicating braided channel facies (Figure 3g). The core of well J91 at depths of 3002.62-3002.85 m shows the presence of light gray coarse-gained pebbly sandstone and light gray medium sandstone. Gravel is enriched in the upper part of the core, and multiple argillaceous stripes are seen in the lower part of the medium sandstone, exhibiting ripple bedding (Figure 3h). Integrated geophysical logging and geological cores data of various wells were incorporated in our study to describe the depositional framework of the member-1 of the LSF. The depositional environment of LSF in the Hangjinqi area is deduced as the braided river. The river course and flood plain are interpreted as subfacies, whereas braided channel, channel-bar, and overbank are interpreted as microfacies. The existence of gray brown mudstone ( Figure 3f) and mud gravel in the light gray oil traces present between the light gray coarse-grained gravel sandstone (Figure 3d), and right box-car shaped characteristics with high GR values (Figure 4), indicates floodplain. These mudstone sediments were deposited in the overbank regions. The abrupt change of mudstone present in the upper part with underlying coarse-grained pebbly sandstone shows that there is a transition from floodplain to braided channel (Figure 3b). The presence of light gray coarse-grained pebbly sandstone (Figure 3b (Figure 3g), sub-angular grains with good sorting (Figure  3e), finning-upward trend (Figures 3b and 4), and left box-car shaped gamma-ray curve characteristics (Figure 4), signifies the fluvial nature of braided channel sediments. The coarse-grained pebbly-sandstone and sandy conglomerate at the bottom of the member-1 of LSF indicates channel-bars [47] (Figure 4).

Seismic Interpretation
Integrated seismic and well log data was employed to make a relationship between the seismic interfaces and geological characteristics. Through the seismic-to-well tie method, two horizons are marked T9d and T9e [48,49] (Figure 5). These two marked horizons denote the first member (P2x 1 ) of the LSF. The interpolations of the interpreted horizons show the major P-fault, which divides the study area into northern and southern parts (Figure 6a,b).  The middle Permian sediments of LSF show parallel internal geometry configuration on the seismic section. The external geometry shows the features of narrow undercutting that indicate channel fill. The seismic reflection configuration of the member-1 of LSF shows the characteristics of medium-amplitude, good-continuity, and medium-frequency (Figure 7a,b). According to the geological data, the lithology of these middle Permian sediments comprised coarse-to-fine-grained sandstone, mudstone with thin intercalations of siltstone. The narrow seismic section of Carboniferous below the Permian sediments shows the disordered weak reflections of low-amplitude and low-continuity which are associated with soft-sediments. The seismic reflections are divergent due to the presence of faulting. These soft sediments are associated with mudstone and coal layers (Figures 2  and 7b).

Fault Characteristics of Lower Shihezi Member-1
The results of the fault distribution of targeted T9d and T9e horizons show that Pfault mainly controls the Hangjinqi area. The P-fault is extending laterally and is the main reason for the presence of frequent low-to-medium ranked faults. The author [31] subdivided the Hangjinqi fault zone (HFZ) into east (P-fault), central (WF), and west (SF) (Figure 1b). The three segments of faults subtly established in the east Hangjinqi area is as follows: (a) late Haixi fault (weak extrusion) developed near well J75 and Shiguhao area, (b) early Yanshan late fault (strong extrusion) developed in the regions of Shiguhao and Azhen areas, and (c) late Yanshan early fault (weak extension and positive inversion) developed in P-fault zone, Lijiaqu fault zone and Shiguhao and Azhen area [11]. The Hangjinqi area is characterized by many thrust faults. The P-fault is north-trending thrust fault [9]. Many small-scale local faults are scattered along the whole region. However, the northern region has suffered more tectonic activity than the southern region (Figure 8a,b).

Structural Mapping
Structure maps provide the relief of the strata below the surface, such as syncline, anticline, and faults. The structural maps of T9d and T9e horizons are made by incorporating the average velocities of all the wells. The results show significant structural variations. The structural depth ranges from 1950 m to 3100 m for T9d (Figure 9a), while it ranges from 1900 m to 3000 m for T9e (Figure 9b). The structural trend of both targeted horizons shows almost same trend having same structural depths. The southern region shows depths of around 2800-3050 m. In contrast, the northern region shows shallow depths of 1950-2400 m. The P-fault played a significant role in dividing the Hangjinqi area into northern and southern regions. The topography of these maps suggests that the northern area is uplifted compared to the southern region. The northeastern (NE) region shows stratigraphic thinning of about 1900 m, compared to northwestern (NW) and southern regions, which shows that the NE region is more uplifted than other regions.

Thickness Mapping
The thickness map displays the thickness of the targeted strata. The variations in the thickness indicate erosion surfaces, slope identification, and structural discontinuities. A thickness map was drawn amongst these two targeted horizons of T9d-T9e. The results suggest vast thickness variations in the member-1 (P2x 1 ) of the LSF. The thickness ranges from 40 m to 110 m. The thickness is lesser in the northern region as compared to the southern region. The thickness in the north part ranges from 45 m to 85 m, while it ranges from 65 m to 105 m in the south area ( Figure 10). The northeastern region's lesser thickness of about 45 m suggests erosion due to uplifting based on the following reasons; (a) faulting intensity towards the north is high, (b) presence of scouring surface and friable argillaceous material in the cores, (c) prominent coarse-grained arenaceous lithology. The NE region is more uplifted as compared to NW and southern regions. These results agree with the results of the structural mapping, which also shows the same trend. The uplifted NE region suggests the origin of the braided channel river within the member-1 (P2x 1 ) of the LSF. The gentle slope trend lies from NE to SW region, providing the flowing direction of braided channels. The thicknesses of the different layers were disturbed by the presence of major P-fault, which offset the sedimentary layers.

Sand-Ratio Distribution
Sand-ratio map provides information regarding the distribution of sandstone and mudstone across the targeted layers. It also showcases the distribution of sand gas accumulation zones. Sand-ratio map was calibrated for the member-1 of the LSF, which lies in between T9d and T9e horizons. The yellow color in the sand-ratio map shows the deposition of minimum sand and maximum mud, whereas cyan color shows the deposition of maximum sandstone and minimum mudstone ( Figure 11). The sand-ratio ranges from 0.4 to 0.9 in the region. However, most areas show maximum values of 0.65-0.9, which shows that the member-1 of LSF is favorable to gas accumulation. The results also give the indication of thick braided channels. The high values of sand/mud ratio gives the indication of channel-bars.

Velocity Optimization and RMS Attribute Map
Before extracting several horizon attributes to identify sand zones, interval velocities of different lithologies are utilized for attribute optimization. The member-1 of the LSF comprised various lithologies such as coarse sandstone (pebbly sandstone, sandy conglomerate), fine sandstone, and mudstone. The results show that the mudstone and coarse-to-fine sandstone have different interval velocities. These differences in the interval velocities indicate the difference in acoustic impedance amongst various lithologies (Figure 12a). Thus, seismic amplitude reflection can be seen in the section, which confirms that the ampllitude attributes can be utilized to identify sand zones. Numerous seismic attributes are employed to identify the behavior of sand accumulation. Several amplitude attributes are evaluated to acquire the best possible results. The RMS attribute provided good results, hence incorporated in the study. RMS map is made between the targeted T9d and T9e horizons. The horizon RMS attribute map shows variations in amplitude values associated with lithological changes, sand/mud zones, and various depositional environments. The high values are associated with shoreward sand facies, whereas low-amplitude values are associated with mud-saturated zones. The RMS map shows high values throughout the map except for the SW region, which suggests that the sand is thoroughly distributed throughout the targeted area. The RMS amplitude values are maximum towards the NE region, where the values are quite low at the SW region. However, wells J72, J69, J91, and J55 towards the SW region lie reasonably in high amplitude values. The noticeable square pattern towards the SW region is due to the presence of another 3D grid that lies in the Hangjinqi area, and is not an artefact (Figure 12b). Corollary, the results of RMS attribute analysis show that the member-1 of the LSF has the potential to produce a good reservoir.

Reservoir Quality Prediction through Petrophysical Modeling
There is one perforation interval within the well J34 (Figure 13a). The depth of the perforated layer ranges from 2337-2341 m. The thickness of the perforated interval is 4 m. The average porosity value of the perforated interval is 13.1 %. The average permeability value of the interval is 0.8 mD. The perforated layer is less affected by mud intrusion and diameter expansion. The log curves of the reservoir section show high resistivity, low GR, low SP, low density, medium AC, and high porosity-permeability values. The test gas production volume is 3192 m 3 /day, and the water volume is 0 m 3 /day. The gas logging curve of the total hydrocarbon value is high at reservoir interval. These log interpretation results suggest that the reservoir is a pure gas layer. Henceforth, well J34 within the LSF belongs to a good sandstone gas reservoir. One perforation interval lies within the member-1 of the LSF within well J52 ( Figure  13b). The depth of the perforated layer ranges from 2317.5-2321.5 m. The total thickness of the perforated interval is 4 m. The average porosity value of the interval is 14.5%. The average permeability value of the interval is 2.6 mD. The perforated layer is less affected by mud intrusion and diameter expansion. The log curves of the reservoir section show medium resistivity, low GR, low SP, medium density, relatively low AC, and high porosity-permeability values. The test gas production volume is 0 m 3 /day, and the water volume is 12 m 3 /day. The gas logging curve of total hydrocarbon value (TG) is minimum close to reservoir depth. These log interpretation results suggest that the reservoir is a dry well. Henceforth, the reservoir within J52 of the LSF belongs to a dry well. The possible reason for the zero gas production within J52 is its location near the P-fault. The faults offset the layers, and the gas through the open spaces was migrated towards the northern region from the southern region.
There is one perforation interval within the well J72 (Figure 13c). The depth of the perforated layer ranges from 2939-2943 m. The thickness of the perforated interval is 4 m.
The average porosity value of the perforated interval is 9.8%. The average permeability value of the interval is 0.31 mD. The perforated layer is less affected by mud intrusion and diameter expansion. The log curves of the reservoir section show medium resistivity, low GR, low SP, low density, medium AC, and low porosity-permeability values. The test gas production volume is 11220 m 3 /day, and the water volume is 2.2 m 3 /day. The gas logging curve of the total hydrocarbon value is close to 10 at reservoir interval. These log interpretation results suggest that the reservoir is not a pure gas but a water-gas layer. Henceforth, well J72 within the LSF belongs to a medium tight sandstone reservoir because of medium resistivity and low porosity-permeability values and water in the gas.

Controlling Factors and Demarcation of Favorable Zones of Sand Accumulation
The evolution of P-fault in the Hangjinqi area controls the migration of the hydrocarbon in the northern region [9]. In addition to the P-fault, many local faults were also developed in the northern region, whereas the faults developed in the southern region were small in numbers and sparse (Figure 8). During the Taiyuan-LSF periods, the depositional environment of the basin was changed from marine environment to continental depositional environment ( Figure 2). Therefore, the structural and thickness map results showed an uplifting trend in the northern region and a deepening trend in the southern zone, thus forming a gentle slope. Moreover, the P-fault was steadily linked by separate reverse faults during the late development of the evolution process, due to which structural transformation zones paved the way for transporting the channels. Therefore, the sedimentary facies of the middle Permian sediments of the LSF comprises fluvial deposits. The main controlling factors include the development of paleogeomorphology, variations in tectonic movements due to the presence of major P-fault, maximum sediment supply, and supporting climate conditions for the formation of braided river channels as the dominant depositional microfacies for the member-1 of the LSF within the Hangjinqi area.
The depositional facies map made through the integrated results of the sand-ratio map and RMS attribute map confirmed the presence of braided river channels ( Figure 14). These braided channels are very thick in the northern region and flow towards the south region. The channels are narrowing, and the major micro-facies developed are channelbars and bradided channel deposits. The RMS and sand-ratio values are quite high, indicating thick-bedded sandstone deposition. The sand-ratio values towards the NE and SE regions are quite high compared to the SW region. The channels towards the SW region are thin, and the sand-ratio and RMS values are relatively low. The wells J73, J93, Y19, and J54 lie within the low RMS zone. In addition, wells J66, Y26, J18, J19, J41, J43, J44, J73, and J83 show minimum sand-ratio values. On the contrary, wells J33, J37, J39, J70, J75, J76, and J91 lie within the maximum sand-ratio zone. Three wells J34, J52 and J72, were chosen to study the test results. The test results of well J34 shows that the perforation layer is a pure gas layer. The high RMS and high sand/mud values at J34 also support these results. The test results of well J52 shows that the perforation layer is a dry gas layer with zero gas volume. The results of the proposed depositional facies map are reliable, showing that J52 lies within minimum sand-ratio zone. Since J52 lies in the vicinity of P-fault, it was heavily affected by tectonic activity. Due to uplifting towards the northern region, the accumulated gas in the southern region was affected and migrated laterally towards the northern region through the open areas in the P-fault [29]. The test results of well J72 shows that the perforation layer is a gaswater layer. Well J72, located towards the SW region of the Hangjinqi area, lies within the relatively medium sand-ratio zone. The RMS values are also optimal for producing a relatively good reservoir in J72 wells. Wells J34 and J72 lies in the channel-bar deposits, whereas well J52 lies within the inter-channel region. Thick braided channels are passing through J34, narrow channels through J72, while no channel are passing through J52. These results shows that J34 lies in the most favorable zone, while J52 is least favorable zone. Overall results of the proposed depositional facies maps predicts that the reservoir quality within the member-1 of the LSF is good for regional gas production.

Conclusions
This study has identified the depositional framework and sedimentary facies controls by analyzing the rock type characteristics, faults and facies distribution, sand-ratio accumulation, and other significant sedimentary features using drilling cores, logs, and 3D seismic data in the member-1 of the lower Shihezi formation in the Hangjinqi area. The results of the cores and well logging showed depositional framework of member-1 reservoir was established into braided channels and channel-bars. The thickness and structural maps suggested that the north area is uplifted as compare to south region. The uplifting in the northeastern region shows that the braided channels flows from north towards south region. The uplifting towards the north causes the structural thinning towards the southern region making a gentle slope towards the southwestern region, due to which the channels become narrower towards SW region. The thick-bedded sand bodies are discontinuous and scattered along the whole area due to the presence of the P-fault, which played a major role in migrating the gas of nearby well J52 from the south towards the uplifted northern region. The test results of well J34 and J72 showed the presence of gas. In addition, we have also highlighted the regions of maximum sand/mud ratio and channel-bars, which are favorable for gas production. In a nutshell, we predicted that the reservoir quality within the member-1 of the lower Shihezi formation is favorable and can produce gas reserves regionally and economically. The proposed facies model will provide further insights towards the development of Hangjinqi area into Hangjinqi gas field.

Data Availability Statement:
The data underlying this article cannot be shared publicly due to reason that it is confidential for the privacy of individuals that participated in the study. However, the data will be shared on reasonable request to the corresponding author.