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(IAOFq) of each field, and its connotation and applicability are further discussed through theoretical deduction. In log-log plot, G vs. IAOFq exhibit highly dependent linear trend, which implicates the compatibility between G and IAOFq 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.

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.

New method for plugging channeling in oil field by nitrogen foam

In order to present a new method for plugging channeling in oil field,the injection modes and validity period of foam system which plugged the formation water layer were studied by means of the experimental model which simulated the real conditions of oil wells existing channeling.Above all,the influence factors including reservoir pressure,permeability,oil saturation and gas-to-liquid ratio were studied through dynamic experiment.Then,in light of the technology characteristics of foam injection in oil field,the comparison between gas-liquid and liquid-gas injection modes was studied.The result shows that the gas-liquid injection mode can ensure the foam injectivity and plugging performance.The plugging validity of nitrogen foam injected into the formation water layer was evaluated in different plugging pressure gradients by the dynamic method which is more reasonable than the static evaluation method in laboratory.The research demonstrates that the plugging validity period of foam decreases with plugging pressure gradient increasing.If the plugging pressure gradient is 0.15 MPa/m,the validity period is 160 h.Finally,a empirical equation and a plate about the plugging validity and the plugging pressure gradient were obtained for forecasting the validity period of foam.

一株分离自地层水的石油降解菌的特性研究:Ochrobactrum intermedium环境分离菌株与临床分离菌株的比较基因组分析（英文）

目的:对一株地层水分离的石油降解菌Ochrobactrum intermedium 2745-2进行生理生化特性的研究、全基因组测序以及比较基因组研究。创新点:首次对一株分离自地层水的石油降解菌O.intermedium 2745-2进行了生理生化特性研究以及基因组测序,从基因组角度解释菌株2745-2对石油的降解能力。通过菌株2745-2与同种其他临床分离菌株的比较基因组学分析,表明2745-2仍具有多种与致病性相关的基因。方法:通过微生物富集培养的方法从油井的地层水中分离石油降解微生物,通过聚合酶链反应(PCR)扩增16S核糖体RNA(r RNA)序列进行比较和分析确定菌株的分类地位属于O.intermedium(图1)。采用Illumina Hi Seq2000对菌株2745-2进行高通量测序,采用Velvet 1.2.07和RAST server分别进行数据组装和注释(表1)。PHAST寻找基因组中的噬菌体相关序列(图4和表2)。通过BLAST+和BRIG对环境分离菌株(2745-2)和临床分离菌株(M86、229E和LMG3301T)进行基因组比较(表3、表4和图5)。结论:首次对一株环境分离的O.intermedium(2745-2)进行全基因组测序,揭示具有多种与石油降解相关的基因。通过环境分离菌株(2745-2)与临床分离菌株(M86,229E和LMG3301T)的基因组比较分析,表明2745-2仍具有多种致病性相关的基因。