Spatial Layout of Cotton Seed Production Based on Hierarchical Classification: A Case Study in Xinjiang, China

Cotton seed production is the main form of agriculture in Xinjiang, China. Unreasonable distribution of cotton seed production results in a waste of water, land, and human resources. In this study, we established a hierarchical classification integrating method; investigated the spatial suitability of climate, land and water resources, and infrastructure; examined the production risk and planting history; and integrated spatial suitability and production risk and history to produce the spatial layout of seed production for early-maturing cotton (EMC), early–medium-maturing cotton (EMMC), and long staple cotton (LSC) in Xinjiang. The results indicated that the appropriate areas for EMC, EMMC, and LSC seed production are 6.4 × 105, 5.5 × 105, and 3.6 × 105 ha, respectively. By combining the suitable areas of seed production for the three cotton species, we concluded that the superior and most suitable area for producing cotton seed of EMC, EMMC, or LSC is located in the western Tarim Basin. The sub-suitable area for cotton seed production of EMC, EMMC, or LSC is mostly distributed in the western and northern Tarim Basin. This research provides a good solution to the selection of cotton seed production base; however, adoption will depend on the actual preference and market factors.

Determination of oil charge timing in the Ordovician carbonate reservoir of the Tahe Oilfield, Tarim Basin, NW China

<p>Determining the timings of oil charge in sedimentary basins are essential to understand the evolutionary histories of petroleum systems, especially in sedimentary basins with complicated tectonic evolution and thermal histories. The Ordovician carbonate reservoir in the Tahe Oilfield, which is located in the northern Tarim Basin, comprises the largest marine reservoirs in China with reserves up to 3.2×10<sup>8</sup> t. This study aims to determine the timings of oil charge in the Ordovician carbonate reservoir in the Tahe Oilfield, Tarim Basin, which basin is subjected to multiple phases of tectonic deformations and oil charge. The phases of calcite veins that contain oil inclusions were systematically investigated by cathodoluminescence observation, in situ rare earth element, C, O, and Sr isotope analyses. The homogenization temperatures of aqueous inclusions that are coeval with oil inclusions were measured to determine the timings of oil charge by combining the burial and geothermal histories. Two phases of calcite veins were judged by the differences in cathodoluminescence color, Ce anomaly, δ<sup>18</sup>O, and <sup>87</sup>Sr/<sup>86</sup>Sr values, which might be caused by variations in the water-rock interaction processes during different calcite phases. Primary oil inclusions with yellow fluorescence were observed in the two phases of calcite veins, suggesting two phases of oil charge. By combining the homogenization temperatures of aqueous inclusions with the burial and geothermal histories, the timing of phase I oil charge was inferred to be 336–312 Ma, and the timing of phase II oil charge was inferred to be 237–217 Ma.</p>

Study of Geostatistical Inversion in the Lithologic Distribution and Velocity Modeling of Thick Igneous Rock in the FY Area, Northern Tarim Basin, China

In the northern Tarim Basin, a large number of thick igneous rocks are encountered in the drilling process in the Permian. Their lithology and velocity are very strongly, which has a great influence on migration imaging of the “beaded” areas. It is very important to conduct the fine lithology identification and high-precision velocity modeling of the igneous rocks for the exploration and development of the reservoirs. A geostatistical inversion method to obtain the igneous-rock lithologic distribution pattern and velocity modeling in the FY area of the northern Tarim Basin is introduced in this paper. The results show that the application of the geostatistical inversion method greatly improves the resolution of lithology identification. This helps us further understand the Permian igneous rocks distribution in the FY area. Comparison between the seismic facies classification maps of the FY study area shows that the obtained velocity model can reflect the lateral distribution of igneous rocks well. At the same time, the velocity model can reflect the variation of igneous rocks velocity in detail and has a high precision. The average velocity error of the wells participating in the inversion is less than 2%, and the minimum average velocity error is 0.23%. Finally, the velocity model is applied to seismic data processing, and the processing results indicate that it can help to improve seismic migration imaging. The study demonstrates that the geostatistical inversion method can provide a high-precision velocity model for formation pressure prediction and seismic data processing and interpretation, ultimately guiding the exploration and development of oil.

Research on the lithofacies and paleogeography of the lower Cambrian Xiaoerbulake Formation in the northern Tarim Basin, northwestern China

Based on the study of cores, thin sections, and outcrops, the sedimentary facies of the lower Cambrian carbonate rocks in the northern Tarim Basin can be divided into four types: restricted platform, open platform, ramp, and basin. Based on the lithologic analysis of thin sections, two-dimensional seismic data interpretation, and an isopach map of the lower Cambrian Xiaoerbulake Formation in the study area, seven sedimentary facies of carbonate rocks were identified, including inner platform depression, shoal, intershoal sea, platform margin, gypsum salt lake, ramp, and basin. The depositional model of the lower Cambrian Xiaoerbulake Formation in the northern Tarim Basin is constructed based on this integrated research. The topset, foreset, and bottomset of oblique progradational reflections are interpreted as the platform margin beach, ramp, and basin environments, respectively. The thicker area with micritic dolomite as the dominant lithology is interpreted as a platform depression. The low-amplitude hummocky reflections are interpreted as shoals that consist of a variety of granular dolomite and algal dolomite. The thinner uplifted area with gypsum and dolomite present in cores is interpreted as a restricted platform with a gypsiferous dolomite tidal flat or lake environment. Well LT1, which was drilled recently in the platform margin and ramp region, as indicated by seismic progradational clinoform reflections, has produced high yields of oil and gas. Supported by the above research results, the map of the lithofacies and paleogeography of the Xiaoerbulake Formation in the northern Tarim Basin was recompiled.