Applied Mechanics and Materials Vols. 295-298

Abstract: Aim at the diversity of coalbed methane well completion methods, grey system is used to select completion method. Firstly, implement production prediction and economic evaluation. Then evaluate five indexes: cumulative gas production, net present value, dynamic payback period, internal rate of return and risk factor. The most appropriate completion method can be got. When apply this evaluation method to Sihe mining of Qinshui basin, results show that pinnate horizontal well is the most suitable completion method, followed by fractured vertical well.

Abstract: Unified Fracture Design for fracturing optimization is a simple and reliable way to push the limit of the injection ability, reported frequently in recent years. However, most studies focus on fracture design under pseudo-steady state flow regime. The analysis of the different pressure systems between water injection well and oil production well tells us that the steady flow regime in the formation takes up most life span of water injection wells, associated with the field experience. To maximize injection capability for fractured vertical water wells under this regime, a physical optimization method is developed based on the concept of proppant number. Meanwhile, two new type curves without consideration of formation damage are obtained for quantifying the correlation between dimensionless injectivity and dimensionless conductivity. Then, calibrated design procedures accounting for gel damage and non-darcy effect, are also proposed. Finally, sensitivity studies are addressed to clarify the effect of several variables on the optimum fracture geometry.

Abstract: Stress-sensitive widely exists in fractured reservoir. In this paper, a mathematical model of flow in stress-sensitive reservoir with horizontal well is established based on experimental data and with process of linearization. By using of Lord Kelvin point-source solution, Bessel function integration and Poisson superimpose formula, the dimensionless pressure response function of horizontal well in infinite stress-sensitive reservoir is obtained. And then the derivative type curve is calculated. Based on the type curve, the characteristics and influencing factors of the fluid flow through porous medium of horizontal well in stress-sensitive gas reservoir are analyzed.

Abstract: The separation of oil/water transition layer in settling tank becomes deterioration during the late oil production. For improving the dehydration of oil - water layer in settling tank, the oxidation technique by chlorine dioxide was adopted for the demulsification. Chlorine dioxide typically is strong oxidizing reagent. The touched materials would be corroded by the chemical. Therefore, it is necessary to evaluate the corrosion of chlorine dioxide for the steel in the settling tank. In this paper, the research was made to the determination of corrosion rate and corrosion morphology of steel equipped for oil/water transition layer treated with Chlorine dioxide oxidation. The experiments showed that, in the oil/water transition layer after treatment, water phase has the highest corrosion rate of up to 0.151 mm/a and lower than the company-formulated standard of 1.0 mm/a, which falls into the permission range (0.1-1.0 mm/a) of the corrosion standard Class 3. From steel-hanging corrosion morphology, it can be seen that the steel corrosion is weaker before the treatment while becoming stronger with the addition of ClO2 system and acidic solution. The reaction and mechanism were also explained on the corrosion chemistry of oil/water transition layer treated by oxidation process. With the experimental data, the oxidation and corrosion performance of chlorine dioxide can be controlled effectively to play an important role for stable production of oilfield.

Abstract: In order to meet the need of separating oil from water in the settling tank of the oilfield, ClO2-oxidation demulsification for oil-water transition layer in settling tank is introduced. In this paper, effects of reaction conditions on ClO2-oxidation demulsification were studied. The results show that the reaction temperature, reaction time and PH value have a heavy effect on the dehydration rate of the oil-water transition layer. With the increasing of the reaction time, the dehydration rate largely rises, and it can reach 84.18% and keep steady when the reaction is in 4 hours. With going the temperature up, the dehydration rate increases in a nonlinear way, and it can reach 85.23% at the temperature of 55°C. By decreasing the PH value, the dehydration rate significantly rises, and the maximum dehydration rate of 84.18% was achieved when adding 0.5 vol. % of the acid. The chemistry was discussed based on the principles and experiments. By demonstrating the experimental data and discussion, we can effectively control the oxidation performance of chlorine dioxide, which is very meaningful for oilfield on the aspect of stable production of petroleum.

Abstract: This paper confirms that the mining of the coal bed methane (CBM) are most significantly influenced by the hydrogeology parameters of the reservoir itself, the hydrogeology parameters, the supply properties and the geological structure of the roof and floor and other neighboring water-bearing rocks hydraulically associated with the coal bed as well as the difficulty degree of CBM mining; a evaluation indicator system structure of the hydrogeology conditions are established based on the foresaid conclusions and the CBM mining hydrogeology conditions are divided into “beneficial, moderate and adverse” grades; this paper finally divides the threshold to grade the hydrogeology condition evaluation indicators and a complete CBM mining hydrogeology conditions evaluation indicator system is founded to evaluate the hydrogeology conditions.

Abstract: The quantity and availability of water injection are affected by geological environments in complex small fault-block oilfields, especially nearby faults. It is a general method to qualitatively determine fault sealing ability by water injection availability. The availability analysis of several injection wells can judge sealing ability of five faults of block M28-1 in JD oilfield. The water injection data show that fault F1, F4, F5 are main areas of pressure releasing for unsealing. Fault F2 and F3 are distributed on each side of the water injection well, which have a little influence on loss of water injection for sealing.

Abstract: Southern Shizhuang Block has simple structure characteristics, relatively thick coal seams (3.1-10.5 m, 6 m in average), and favorable burial depth (450-900 m). The gas content of the No.3 coal seam in the Shanxi formation ranges from 6-20 m³/t, and it increases from the southeast to northwest area in the southern Shizhuang Block. Gas content is high in the structural low in the area, which means the gas accumulation is controlled by the geological characteristics of local structure and hydrogeologic conditions.

Abstract: Pressure maintenance such as gas cycling which re-injection of produced lean gas into the reservoir are common practices and effective measures to improve the development performance of gas condensate reservoir. However, effectively control of gas channeling and control water cut of horizontal well in gas reservoir with aquifer both the keys to improve the development effectiveness. There are many factors that respond for gas channeling and water cresting, single factor experiment is difficult to obtain reliable result. Orthogonal experimental design, also called Taguchi experimental design, is widely used in various fields of scientific research. This paper applied Taguchi experimental design, an L9 orthogonal was used to the X gas reservoir numerical simulation to carry out sensitivity analysis among four factors which are the well pattern, gas cycle time, gas offtake, recirculating ratio.

Abstract: The system adopted the way of the combination of software and hardware which used to detect oil pipeline leakage and located the accurate leak point. The hardware circuit using STC12C5A60S2 SCM、various types of sensors and MAX485 network and so on. Application of the Kingview technology to design a set of leakage monitor screen in software component. The system uses different sensors to measure the changes in various parameters of pipeline. And by changing parameters to judge whether a leakage happened. If it judged the presence of oil spill then upload the alarm information step by step, after terminal PC receives various parameters of information and then display the information of each code on monitoring interface and alarm the exact location, at the same time sends alarm sound.