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The dolomite reservoirs in the fourth member of Leikoupo formation of the western Sichuan gas field have good prospects for natural gas exploration and development. However, the conventional and one-dimensional nuclear magnetic resonance (1D NMR) logging data are not sufficient for a definitive classification of the reservoir fluid type, likely because of heterogeneity of the reservoirs. Through geological characteristics analysis, log response analysis and two-dimensional (2D) NMR experiment, the environmental factors and technical parameters leading to the differences between the laboratory results and actual logging data were determined. According to the analysis of T2-T1 and T1/T2 (R) differences, the distribution range of drilling fluid, bound fluid, movable water and natural gas signals in the 2D NMR spectra was delineated to build a gas-water 2D NMR identification chart. The results obtained using the identification chart were verified with the actual drilling test results. Complementary to conventional and 1D NMR logging, the 2D NMR identification method was proposed, and can be used to determine the fluid properties in the dolomite reservoirs effectively.

Formation porosity can be calculated from one-dimensional nuclear magnetic resonance (NMR) logging data with a fixed cutoff value and the volume model of conventional logging data. However, the porosity calculated with this method often appears to be overestimated in the enlarged hole section. In this work, the calculation methods for T2 and T1 nuclear magnetic porosity from NMR results of core samples and two-dimensional NMR logging data were investigated. Firstly, the characteristics of NMR relaxation spectra of fluids at different pore sizes were obtained and used to analyze the distribution range of pore diameter and affecting factors of the cutoff value of the drilling fluid peak. A model for estimating the cutoff value of the drilling fluid relaxation time was then established. A method for calculating the effective porosity was then proposed with variable cutoff value of clay bond water relaxation time, according to the deterministic principle about cutoff value of clay bond water relaxation time in un-enlarged and enlarged hole section. The method proposed was applied to the data from many wells, and demonstrated better accuracy than the traditional method using T1 distribution spectra. The method can effectively solve the problem of overestimated porosity in the enlarged hole section and meet the requirement for reservoir evaluation.

Two-dimensional nuclear magnetic resonance (2D NMR) logging has been increasingly used in the reservoir modeling and fluid identification. A series of problems were encountered when applying the technique in the Chuanxi gas field, including poor efficiency in logging data collection and mismatch between the logging evaluation and reservoir properties. By comparing two commonly-used 2D NMR logging intersection methods and analyzing in-field results, we optimized the design. It was found the T2-T1 method was more suitable than the T2-D method for tight reservoir evaluation. The activation set TGR01 (tight gas reservoir 01) derived from the optimized method, was shown to be superior to the existing method for the tight gas reservoir. At the same time, the T2-T1 intersection method was found to be able to identify different fluids effectively, and applicable to the evaluation of tight gas reservoir.

Uterine stromal cell decidualization is a dynamic physiological process in which cell proliferation, differentiation and apoptosis are orchestrated and occur in a temporal and cell-specific manner. This process is important for successful embryo implantation. Many cell-cycle regulators are involved in decidualization. The protein cyclin G1 is a unique regulator of the cell cycle with dual functions in cell proliferation. It was reported that cyclin G1 is expressed in mouse uterine stromal cells during the period of peri-implantation. To prove the function of cyclin G1 in mouse uterine stromal cells during this period, immunohistochemistry was used to stain mouse uterine tissues on days 4-8 of pregnancy. The results showed obvious spatial and temporal expression of cyclin G1 in uterine stromal cells, and that it is expressed in the cells of the primary decidual zone (PDZ) on day 5 and secondary decidual zone (SDZ) on days 6 and 7, when the stromal cells experienced active proliferation and differentiation was initiated. Applying the decidualization model of cultured primary stromal cells in vitro, we further revealed that the expression of cyclin G1 is associated with decidualization of stromal cells induced by medroxyprogesterone acetate (MPA) and estradiol-17β (E2). RNA interference was used for the knockdown of cyclin G1 in the induced decidual cells. Flow cytometry analysis indicated that the proportion of cells in the S stage was increased, and decreased in the G2/M phase. Our study indicates that cyclin G1, as a negative regulator of the cell cycle, plays an important role in the process of decidualization in mouse uterine stromal cells by inhibiting cell-cycle progression.