Applied Mechanics and Materials Vols. 448-453

Abstract: Based on Landman variable density perforation model, a horizontal well variable-density completion coupling model is derived under non-homogeneous formation conditions. And an actual well is taken for example to calculate the production fluid profile of horizontal well under different perforation densities. The results show that the production fluid profile of the high and low permeability section tends to be even with the decrease of the perforation density of the high-permeability section. Based on the coupling model, optimization methods for the variable-density completion of horizontal well under uneven stratum conditions are put forward. The production fluid profiles of optimized perforation model, actual perforation model, and even perforation model are compared. According to the results, the horizontal well corresponding to the optimized perforation model is with the most balanced inflow profile.

Abstract: During the process of development for shale gas reservoirs, the permeability of fractures will decrease due to stress-sensitive effect. Adsorption is also an important mechanism which determines the production of shale gas reservoirs. Therefore, the effect of stress sensitivity and adsorption must be considered in the numerical model for pressure transient analysis. In this paper, a dual-porosity model was established considering both mechanisms, and finite-difference method was used for discretizing fluid equations. Then Newton method was applied for solving the resulting algebraic equations, and the typical curves in terms of dimensionless pseudopressure and time were drawn with different sets of parameters. The numerical well-testing model provides theoretical basis for interpreting production data of shale gas reservoirs.

Abstract: With the beginning of unconventional exploration and exploitation of natural gas in Brazil, the question of how to transport the product is concerned. Being the transport an essential part to supply energy to consumers, to move towards energy efficiency one should seek sustainability in the logistic process from the production until delivery at final destination. The objective of this study is the regional assessment of two transport modes for natural gas: by pipeline or as secondary energy in the form of electricity. Since society no longer accepts development at any cost, to determine the best mode of transport three other factors have been added to the techno-economic factor, which are environmental and social impacts, and political risks, defining specific methods to internalize externalities. The full cost analysis considers the four factors under a balanced importance degree for planning towards sustainability. A case study deals with the energy transport (natural gas and electricity) to meet consumer markets in the state of Minas Gerais, between exploratory gas fields at Sao Francisco river basin. The research method employs the most relevant elements of analysis within the four dimensions, assigning specific valuations according to transport mode particularities and providing the best product transportation mode. To attend the region demand for energy, full cost analysis points to energy transport in the form of electricity as the best alternative.

Abstract: In this paper, by using nonlinear dynamical theory and Arbitrary Lagrange Eulerian (ALE) algorithm in LS-DYNA ^3D finite element program, a method of numerical simulation is used to study dynamical response of buried gas pipeline underground shock wave of underground explosion. The simulation results shows that it is feasible for the numerical simulation method in this paper to study dynamical response of buried pipelines underground shock waves from explosion. the conclusion in this paper may provide significant reference for the risk evaluation and disaster prevention of buried gas pipeline.

Abstract: Darcy's law is found be not applicable to fluid flow in small pore throat, and the mechanism for the nonlinear flow is still unclear to date. The paper analyzed the influence of various types of micro forces in porous media on fluid flow, based on the existing experimental results and theoretical knowledge of micro-scale flow. Mathematical model for flow in small tube was established with the consideration of Van der Waals force between solid and liquid. By simulating velocity distribution and the average flow under the Poiseuille flow, we get that with the decrease of the micro tube size, the Van der Waals force between solid and liquid increases and the effect on flow pattern of fluid in the tube increases, so that the Van der Waals force between solid and liquid in the tiny pore flow should not be ignored.

Abstract: In order to optimize select the best experimental conditions on testing tight sandstone starting pressure gradient in the laboratory, the advanced equipment of ASF300^TM Used to do experiments of constant pressure injection and constant flow injection under the conditions of two modes: constant confining pressure and constant net confining pressure, the data obtained was analysed in the form of linear regression fitting, obtained four different starting pressure gradient values under the different conditions. The experimental results and test methods were careful analysed and comprehensive evaluated according to each different experimental conditions and combined with the existing theory. The experimental results indicate that constant flow experiment is not suitable for large-scale use in the laboratory because of its longer time consuming under the condition of constant confining pressure mode, and the starting pressure gradient values are often larger, net confining pressure can be controlled more than 11 MPa to reduce experimental error. Under the condition of constant net confining pressure mode, the result is reliable, but it takes time longer too. On the contrary, the experiment of constant pressure injection takes time shorter, and the results are accurate under the mode of constant net confining pressure. But under the mode of constant confining pressure the value is on the high side. Based on the above, the best condition of testing starting pressure gradient for tight sandstone is net confining pressure mode and the fluid injected in the form of constant pressure.

Abstract: When the buried depth of water level is very large, the air compressor is used in pumping test. In the limited conditions, the value of the water level was not measured, but the recovery value of water level could be measured. In this case, the s_p value of the water level drawdown was not able to be measured accurately when the pumping test stopped. So the hydraulic conductivity of aquifer could only be determined according to the linear graphic method of the water level recovery test. However, water level recovery characteristics of each period were not the same, and the raising rate of water level were not equal. Thus, there was a deviation when the hydraulic conductivity was solved with the linear graphic method. According to the existing data, the thesis combined the water level recovery fitting of the entire curve fitting with Dupuit formula of artesian well, determining the s_p value and hydrogeological parameters of aquifer. After comprehensive analysis, the parameters obtained are more reasonable, which can provide a good reference for in-situ mining of oil shale in this area.

Abstract: Nano/micro polymer particles of acrylamide (AM), acrylic acid (AA), methyl methacrylate (MMA) are used to enhance oil recovery. Swelling kinetics of nano/micro polymer particles were investigated through experimental analysis and statistical analysis. The effect of salinity and temperature on swelling behavior over time is studied experimentally. The swelling kinetics of nano/micro polymer particle was described by second order kinetics. Equilibrium swelling ratio and swelling rate were obtained through nonlinear regression. The quantitative relationships between equilibrium swelling ratio and salinity, temperature were presented. Results show that the swelling ratio increases with increasing temperature or decreasing salt concentration. The study provides a direct perspective of swelling characteristics of nano/micro polymer particles for oil recovery enhancement.

Abstract: Heavy oil Anaerobic degradation by microbial had important theoretical significance and application value of reservoir residual oil biological gasification. The microbial consortium SLY-1 which was enriched from heavy oil reservoir in Shengli oilfield had been cultured at 55°C. DGGE showed that there were two isolated strains which were Anaeromyxobacter sp. and Anaerobaculum sp. respectively and three uncultured bacteria included in SLY-1. After 380d’s culture, SLY-1 had been produced 1006 μmol of methane accounting for 95.2% and 4.8% of other gases (butane, pentane, 2,2-two methyl butane hydrocarbon, 2-cyclopentane etc.). The rate of heavy oil degradation by microbial consortium SLY-1 reached 30.6%. The high viscous microbial consortium could lay the foundation for the residual low-grade heavy oil gasification.

Abstract: Buried hill reservoir fracture description and reservoir simulation technology have been a hot research, but also is one of the key issues that restrict the efficient development of such reservoirs. Based on JZ buried hill reservoir which heterogeneity is strong, some wells water channeling fast and difficult to control the situation for fracture affect, a typical block of dual medium reservoir numerical models which was comprehensive variety of information, discrete fracture characterization and geological modeling is established. The fractured reservoir numerical model is simulated through Eclipse software to seek the law of remaining oil distribution. Through the reservoir geological reserves and production history matching, the remaining oil distribution of main production horizon is forecasted. On this basis, the results of different oilfield development adjustment programs are predicted by numerical simulation.