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

Abstract

The tight gas reserves in the Hangjinqi area are estimated at 700 × 109 m3. 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 (P2x1) 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.

Estimation of porosity and facies distribution through seismic inversion in an unconventional tight sandstone reservoir of Hangjinqi area, Ordos basin

“…Also, the Hangjinqi has several wells, however, the prospective porous zones are uncertain (Aqsa et al, 2022b). The reservoir within the Hangjinqi area and nearby fields lie within the tight sandstone reservoirs of Shihezi and Shanxi Formations (Wang et al, 2020;Anees et al, 2022a;Zhang et al, 2022). Also, it has been discovered that the Upper Paleozoic sandstones of the Hangjinqi region contain a significant amount of gas (Qin et al, 2022).…”

Sand-ratio distribution in an unconventional tight sandstone reservoir of Hangjinqi area, Ordos Basin: Acoustic impedance inversion-based reservoir quality prediction

“…The tight sandstones of the Lower Shihezi Formation, which include sandy fluvial conglomerate and coarse-to-fine-grained sandstones, are acting as the primary reservoir within the Hangjinqi area (Zhang et al, 2009;Anees et al, 2019). Recent studies show that the member-1 of the Lower Shihezi Formation has good reservoir quality and has the potential to develop gas reserves on a regional and commercial scale (Anees et al, 2022a). In addition, the northern region of the member-2 and member-3 of the Lower Shihezi Formation also suggested good favorable zones for gas exploration (Anees et al, 2022b).…”

Application of Machine Learning for Lithofacies Prediction and Cluster Analysis Approach to Identify Rock Type

“…This is a linear mathematical strategy for condensing a big set of variables (seismic characteristics) into a smaller set that retains the majority of the independent information variation found in the larger data set [18,19]. One can distinguish sedimentary units with similar log characteristics by gathering data from several good logs [20][21][22][23][24]. In the literature, sedimentary units established on this basis and characterized from wireline logs were referred to as electrofacies or logfacies [17,[25][26][27].…”