Histone Lysine Methyltransferase SDG8 Is Involved in Brassinosteroid-Regulated Gene Expression in Arabidopsis thaliana

Citation: Wang, X., Chen, J., Xie, Z., Liu, S., Nolan, T., Ye, H., et al. (2014). Histone lysine methyltransferase SDG8 is involved in brassinosteroid- regulated gene expression in arabidopsis thaliana.The plant steroid hormones, brassinosteroids (BRs), play important roles in plant growth, development and responses to environmental stresses. BRs signal through receptors localized to the plasma membrane and other signaling components to regulate the BES1/BZR1 family of transcription factors, which modulates the expression of 4,000-5,000 genes. How BES1/BZR1 and their interacting proteins function to regulate the large number of genes are not completely understood. Here we report that histone lysine methyltransferase SDG8, implicated in Histone 3 lysine 36 di- and tri-methylation (H3K36me2 and me3), is involved in BR-regulated gene expression. BES1 interacts with SDG8, directly or indirectly through IWS1, a transcription elongation factor involved in BR-regulated gene expression. The knockout mutant sdg8 displays a reduced growth phenotype with compromised BR responses. Global gene expression studies demonstrated that SDG8 plays a major role in BR-regulated gene expression as more than half of BR-regulated genes are differentially affected in sdg8 mutant. A Chromatin Immunoprecipitation (ChIP) experiment showed that H3K36me3 is reduced in BR-regulated genes in the sdg8 mutant. Based on these results, we propose that SDG8 plays an essential role in mediating BR-regulated gene expression. Our results thus reveal a major mechanism by which histone modifications dictate hormonal regulation of gene expression

Effects of Yishen Pinggan Recipe on Renal Protection and NF- κ

Inflammation is an important etiological factor of hypertensive renal damage. The effects of Yishen Pinggan Recipe (YPR) on urine microalbumin, histology, and NF-κB/P65, IκB-α, IL-1β, IL-6, and TNF-α in renal tissues were evaluated in SHR to explore the mechanism of its renal protection in hypertensive renal damage. The SBP of 12-week-old SHR was 192.41±3.93 mmHg and DBP was 142.38±5.79 mmHg. Without treatment, the 24-week-old SHRs’ SBP was 196.96±3.77 mmHg and DBP was 146.08±4.82 mmHg. After the 12-week-old SHR were administered YPR for 12 weeks, the rats’ SBP was 161.45±7.57 mmHg and DBP was 117.21±5.17 mmHg; YPR could lower blood pressure in SHR. And renal function damage was observed in 24-week-old SHR without treatment, manifested as urine protein and morphological changes which could be inhibited by YPR. In addition, YPR could reduce the expression of inflammatory cytokines (IL-1β, IL-6, and TNF-α) in kidneys. It could also inhibit the nuclear translocation of NF-κB p65 and degradation of IκB-α in renal cells, indicating that the NF-κB signaling pathway was inhibited by YPR. Finally, the study suggests that YPR could significantly improve the renal function in SHR. The mechanism could be attributed to its inhibition of renal NF-κB signaling pathway and inflammation

Experimental Study on the Physical Simulation of Water Invasion in Carbonate Gas Reservoirs

Water invasion in carbonate gas reservoirs often results in excessive water production, which limits the economic life of gas wells. This is influenced by reservoir properties and production parameters, such as aquifer, fracture, permeability and production rate. In this study, seven full diameter core samples with dissolved pores and fractures were designed and an experimental system of water invasion in gas reservoirs with edge and bottom aquifers was established to simulate the process of water invasion. Then the effects of the related reservoir properties and production parameters were investigated. The results show that the edge and bottom aquifers supply the energy for gas reservoirs with dissolved pores, which delays the decline of bottom-hole pressure. The high water aquifer defers the decline of water invasion in the early stage while the big gas production rate accelerates water influx in gas reservoirs. The existence of fractures increases the discharge area of gas reservoirs and the small water influx can result in a substantial decline in recovery factor. With the increase of permeability, gas production rate has less influence on recovery factor. These results can provide insights into a better understanding of water invasion and the effects of reservoir properties and production parameters so as to optimize the production in carbonate gas reservoirs

Water-gas ratio characteristics and development concepts for water-producing gas reservoirs

Water production from gas wells is a key factor affecting the effectiveness of gas-reservoir development, and it poses serious challenges in terms of increasing the degree of recovery during the waterless production stage and reducing the impact of water production on gas-reservoir development in the middle and later periods. Thus, gas reservoirs must be efficiently exploited on the basis of identifying gas-water layers accurately, defining gas-water relationships, and understanding gas-water production performance. Accordingly, this study analyzes the production characteristics in gas reservoirs with different gas-water relationships, and it summarizes the rules that determine water-gas ratios. The results reveal that the water-gas ratio increases rapidly in the early stage of water production, but after a period of time, it enters a relatively stable state in which it is almost a fixed value. According to the material balance equation, the theoretically calculated water-gas ratio is fully consistent with the production rules for an entire confined gas reservoir. This shows that the reality of gas-well-water production must be faced, and that the development of water-bearing gas reservoirs must accommodate gas and water co-production. The gas-water relationship, water body scale, and reservoir heterogeneity determine the time of water breakthrough and the water-gas ratio. Therefore, we should change the traditional “water fear” concept in gas-field development, aim for an overall improvement in recovery, face up to the fact that gas wells produce water, and coordinate the development of multi-wells for entire gas reservoirs, all of which will achieve the ultimate goal of improved gas recovery

Experimental Study on the Effective Utilization of Reserves in Tight Sandstone Gas Reservoirs and Their Applications

The effective utilization of reserves in tight sandstone reservoirs is one of the major concerns in terms of the development of tight sandstone gas reservoirs. However, the characteristics of reserve utilization are not fully understood, and many uncertainties still exist in the process. For this purpose, long cores on the Su 6 block of Sulige tight sandstone gas field in China were selected, and a multipoint embedded measurement system was established to study the characteristics of effective reserve utilization. Then, the effects of the related reservoir properties and production parameters were investigated. Based on the similarity theory, the effective conversion relationship between the physical experiment and the actual field production was established. The results showed that the pressure distribution in the exploitation of tight gas reservoir is nonlinear, and water cut in the reservoir will hinder the effective utilization of reserves. The lower the reservoir permeability, the larger the negative effect of water on reservoir utilization. Lower gas production rate and higher original pressure are associated with a smoother drawdown curve, which results in larger reserve utilization. The moving boundary expands with time, and its initial propagation velocity increase and then decrease. Additionally, the water cut in the reservoir can delay the spread of moving boundary propagation. The experimental results are consistent with the actual results of the field production by the similarity criterion, which can reflect and predict the production performance in tight gas reservoirs effectively. These results can provide a better understanding of reservoir pressure distribution and effective utilization of reserves to optimize the gas recovery and development benefit in tight sandstone gas reservoirs

A coupling model for gas diffusion and seepage in SRV section of shale gas reservoirs

A prerequisite to effective shale gas development is a complicated fracture network generated by extensive and massive fracturing, which is called SRV (stimulated reservoir volume) section. Accurate description of gas flow behaviors in such section is fundamental for productivity evaluation and production performance prediction of shale gas wells. The SRV section is composed of bedrocks with varying sizes and fracture networks, which exhibit different flow behaviors – gas diffusion in bedrocks and gas seepage in fractures. According to the porosity and permeability and the adsorption, diffusion and seepage features of bedrocks and fractures in a shale gas reservoir, the material balance equations were built for bedrocks and fractures respectively and the continuity equations of gas diffusion and seepage in the SRV section were derived. For easy calculation, the post-frac bedrock cube was simplified to be a sphere in line with the principle of volume consistency. Under the assumption of quasi-steady flow behavior at the cross section of the sphere, the gas channeling equation was derived based on the Fick's laws of diffusion and the density function of gas in bedrocks and fractures. The continuity equation was coupled with the channeling equation to effectively characterize the complicated gas flow behavior in the SRV section. The study results show that the gas diffusivity in bedrocks and the volume of bedrocks formed by volume fracturing (or the scale of fracturing) jointly determines the productivity and stable production period of a shale gas well. As per the actual calculation for the well field A in the Changning–Weiyuan Block in the Sichuan Basin, the matrix has low gas diffusivity – about 10−5 cm2/s and a large volume with an equivalent sphere radius of 6.2 m, hindering the gas channeling from bedrocks to fractures and thereby reducing the productivity of the shale gas well. It is concluded that larger scale of volume fracturing and higher fracture density in the SRV section are important guarantees for efficient development of shale gas reservoirs

Experimental study on water invasion mechanism of fractured carbonate gas reservoirs in Longwangmiao Formation, Moxi block, Sichuan Basin

Fractured carbonate gas reservoirs feature high heterogeneity and difficulty in development, and the invasion of edge and bottom water intensifies the complexity of exploitation of such gas reservoirs. In this study, reservoir cores with a permeability of 0.001 mD, 0.1 mD, and 10 mD were selected by analyzing the fracture characteristics of the Longwangmiao gas reservoir, and water invasion in fractured carbonate gas reservoirs with edge and bottom water was simulated using an experimental system to investigate the effects of different parameters on gas reservoir exploitation. The results show that the larger the water volume ratio, the more serious the water invasion and the lower the recovery factor. But water aquifer did not strongly affect the recovery factor once the water aquifer exceeded a critical value. The higher the gas production rate, the faster the water invasion and the smaller the recovery factor. The recovery factor peaked when the gas production rate was equivalent to the gas supply capacity of the matrix to the fractures. For gas reservoirs with the overall permeability, the higher the matrix permeability, the higher the recovery factor. Although an appropriate fracturing scale was able to enhance the recovery factor when its matrix permeability was low, an excessive fracturing scale would cause water to flow along the fractures at a rapid rate, which further caused a sharp decline in the recovery factor. With the increase of matrix permeability, fractures exerted a decreasing effect on gas reservoirs. These results can provide insights into a better understanding of water invasion and the effects of reservoir properties so as to optimize gas production in fractured carbonate gas reservoirs

Correlation between per-well average dynamic reserves and initial absolute open flow potential (AOFP) for large gas fields in China and its application

Based on performance data of over 600 wells in 32 large gas fields of different types in China, the correlation is established between per-well average dynamic reserves (G¯) and average initial absolute open flow potential (q¯IAOF) of each field, and its connotation and applicability are further discussed through theoretical deduction. In log-log plot,G¯ vs.q¯IAOF exhibit highly dependent linear trend, which implicates the compatibility betweenG¯ andq¯IAOF attained through development optimization to reach the balance among annual flow capacity, maximum profits and certain production plateau, that is to match productivity with rate maintenance capacity. The correlation can be used as analogue in new gas field development planning to evaluate the minimum dynamic reserves which meet the requirement of stable and profitable production, and facilitate well pattern arrangement. It can also serve as criteria to appraise the effectiveness and infill drilling potential of well patterns for developed gas fields. Key words: large gas fields in China, initial AOFP, dynamic reserves, type curve, infill drilling potentia

Research on types of gas reservoirs divided by seepage capacity and their seepage mechanism, law and productivity

In view of the diversity of gas reservoir classification and the differences of characteristics of geology and development in different gas reservoirs, it is necessary to study the adaptability of gas reservoir classification. This paper analyzes and summarizes the current classification methods of gas reservoirs, studies the microscopic pore characteristics and seepage mechanism of different gas reservoirs. The commonalities and individualities of seepage laws in different gas reservoirs are determined, the key factors that determine the development dynamics and effects of gas reservoirs are proposed, and the gas reservoirs types are divided from the perspective of development. The results show that the development characteristics of gas reservoirs are determined by the seepage law, and the seepage law is determined by the microscopic pore characteristics. Therefore, from the perspective of development, the microscopic pore characteristics are the fundamental of gas reservoir classification. Gas reservoirs can be divided into four types: tight, low permeability, medium and high permeability, and fractured. This classification method can unify the types of gas reservoirs according to the seepage laws of different gas reservoirs, establish corresponding seepage models, evaluate productivity, and predict performance. It is of great significance for rational, efficient and scientific development of gas fields

Shale high pressure isothermal adsorption curve and the production dynamic experiments of gas well

The high pressure static adsorption curves of shale samples from Silurian Changning-Weiyuan Longmaxi Formation were tested by using high pressure isothermal adsorption equipment. The physical modeling of depletion production was tested on single cores and multi-core series by using self-developed shale gas fluid-solid coupling experiment system. The adsorption and desorption laws were summarized and a high pressure isothermal adsorption model was established. The calculation formula of gas content was corrected, and the producing law of adsorption gas was determined. The study results show that the isothermal adsorption law of the shale reservoir under high pressure was different from the conventional low pressure. The high pressure isothermal adsorption curve had the maximum value in excess adsorption with pressure change, and the corresponding pressure was the critical desorption pressure. The high pressure isothermal curve can be used to evaluate the amount of adsorbed gas and the producing degree of adsorption gas. The high pressure isothermal adsorption model can fit and characterize the high pressure isothermal adsorption law of shale. The modified gas content calculation method can evaluate the gas content and the proportion of adsorbed gas more objectively, and is the theoretical basis of reserve assessment and production decline analysis. The producing degree of adsorption gas is closely related to the pressure, only when the reservoir pressure is lower than the critical desorption pressure, the adsorption gas can be produced effectively. In the process of gas well production, the pressure drop in the near-well area is large, the production of adsorption gas is high; away from the wellbore, the adsorption gas is low in production, or no production. Key words: shale, high pressure isothermal adsorption, excess adsorption, critical desorption pressure, shale gas, adsorption curv