Advanced Materials Research Vols. 524-527

Abstract: Oil displacement efficiency of oil sands can be improved by combining low-frequency resonant wave with chemical displacement agent. Through experiments targeted on oil displacement effect of the compound oil displacement agent, we selected the most suitable one for a certain oilfield: 15~20 g/L NaOH+20~25 g/L Na₂CO₃＋9~12 g/L XY. Besides, on the basis of selected compound oil displacement agent, the influence of vibrational wave on oil displacement effect was also investigated according to vibration principle of low-frequency artificial vibration. Results show that, when the frequency of artificial vibration is 25-40Hz, acceleration exceeds 0.6 m/s² and effective time is 12min, oil displacement efficiency achieved 97.26%, indicating that oil displacement effect of recombination action is better than that of chemical method alone, hence low-frequency resonant wave can be used in oil sands displacement.

Abstract: The concentration of carbon dioxide gas in atmosphere is remarkably increasing because of burning fossil fuels, such as coal, natural gas and oil. CO₂ is an important Greehouse Gas which results in global warming, and it also threatens human life security and social economy sustainable developing. CO₂ geological storage is considered to be a fairly significant way to seal CO₂ permanently, it can also slow down global warming. Coals have a super adsorption capacity, especially to CO₂, because of the special dual porosity and huge specific surface. Therefore, CO₂ can be injected and sequestrated in coal seams by geological storage. Geological storage of CO₂ can not only reduces its concentration in atmosphere, but also can enhance coalbed methane production synchronously. The paper discusses CO₂ injection and sequestration in coal bed to enhance CBM production mechanism, feasibility and propose a technical route. Experiments show that the technical route of CO₂ geological storage to enhance CBM production is feasible, and the technical of CO₂ geological storage is good for slowing down globle warming and reducing gas accidents.

Abstract: In this paper, An improved genetic algorithm that Powell genetic annealing exact penalty function method was proposed to deal with the non-linear characteristics in gas well production dynamic optimization model. The direct method with Powell to unconstrained optimization problems as a parallel operator as selection, crossover and mutation operator, was embedded into the basic genetic algorithm. Powell operator was defined in genetic algorithm and using annealing exact penalty function control penalty term, so the hybrid genetic algorithm for the global optimal solution to unconstrained optimization problem was made. The method avoided the difficulties of solving the model gradient, and effectively overcome searching local optimal solution and not high success probability by artificially giving more initial point to calculate and seek the optimal solution with Powell method. And the method significantly improved the convergence probability of the global optimal solution in the genetic algorithm. The method was practical and effective by analysis of examples, and it can give suggestion for gas well reasonable production system.

Abstract: This paper presents experimental work on the research of the mechanism of oil displacement of steam drive and high-temperature-compound steam drive, which in order to improve the conventional steam drive technology and increase the recovery of heavy oil. Many experiments were done with the sand-packed model under the formation condition. The results show that: (a) the high-temperature-compound steam drive could extend the water breakthrough time, increase the permeability of oil phase, reduce the residual oil saturation; (b) reducing the viscosity by CO2 dissolution, maintaining the pressure, improving the oil flow ratio, dissolved gas drive，Improving oil displacement efficiency，all of above were the increase production mechanism of high- temperature-compound steam drive.

Abstract: Channeling flow frequently occurs during the high pressure water injection of low permeability reservoir. The injection process is complex and covers so many parameters of which the contribution to channeling flow is necessarily to be studied. In this paper, numerical simulation is combined with sensitivity analysis method to calculate the significance of the weight of parameters to the channeling flow. First the values of different parameters are produced by using Latin hypercube method; second, by using these parameters, finite element model have been established and simulated, and the quantity of channeling flow has been calculated; then Spearman rank relation is applied to measure the relation of parameters and channeling flow. The results states that, in 10 years continuous injection, the well spacing and injection pressure have significant impact on the channeling flow. This states that during the application of high pressure water injection, the pressure and well spacing should be controlled especially.

Abstract: The SAGD test zone in the Guantao reservoir of the Du84 Block in the Liaohe Oilfield belongs to a massive reservoir with top water, which may have the challenge of top water breakthrough along with the propagation of steam chamber. Flue gas assisted SAGD technique is proposed to slow down water break through. Laboratory experiments have been conducted to study the dissolubility of flue gas in Liaohe dehydrated super-heavy oil. The result of the experiments indicates that the viscosity of oil/gas mixture reduces drastically, and the rate of viscosity reduction almost shows linear increase after flue gas dissolved in super-heavy oil. The steam chamber extension feature and development characteristics of SAGD and flue gas assisted SAGD were compared by numerical simulation. The results show that flue gas exits in the top of reservoir because of gravitational differentiation, which can inhibit steam overlay, reduce heat loss to cap rock, and increase heat efficiency.

Abstract: Abstract. Low permeability water-flooding gas reservoir easy to cause the well bottom effusion in the middle of development,Effusion was often can't take out.Then with the function of capillary forces，the effusion will be absorbed in pore of rocks around the bottom well,and the Porous Medium part was block, The gas phase circulation pore canal becomes small,finally gas-phase effective permeability will be influence in the rocks,reduced pore channel permeability,made the productivity decline。The paper,the base of special experiment,analysis relation between the rate of damage about core permeability and imbibitions water saturation,and Introducing the correlation coefficient to the capacity formula of reverse imbibitions gas reservoir ,then get the capacity formula of the water flooding gas reservoir for realize the similar gas reservoir reverse imbibitions damage degree provides the basis.

Abstract: Aiming at the heterogeneity characteristics of fractured reservoir, a new type of nitrogen foam flooding agents is proposed. The gas/liquid ratio of nitrogen foam flooding is selected as 3:1, and the injection rate is selected as 3mL/min by the evaluation of foam resistance factor using core flooding equipment. In addition, this foam system has a better performance in the situation of low oil saturation. The results of nitrogen foam flooding show that it can enhance oil recovery by 38% after water flooding using artificial cuboid fractured core, indicating this nitrogen foam formula is suitable for EOR in fractured reservoir.

Abstract: It is of great significance to select the reasonable support pattern and support parameters for accurately determining the magnitude of the broken rock zone of roadway. At present, the test methods of the broken rock zone of the roadway surrounding rock all have stated disfigurements and deficiency. The borehole imaging method has advantages: simple operation and the test results being intuitive and reliable. The test results and analysis of the broken rock zone of rail crossheading in 3down 109 coal face of Luxi Coal Mine show that the test results consistent well with the actual situation and they have practical reference value for the test and application of the broken rock zone of the roadway surrounding rock.

Abstract: With the characteristics of low permeability, pressure and abundance, it's extremely hard to exploit the super low permeability reservoirs in ChangQing oil field. For this reason, the water injection recovery technique has been widely used. Analysis showed that a serious problem of high energy consumption exist in the water injection system, the power consumption of which accounts for about 44%. And the energy cost of pump units reach up to 43%, it's the highest energy consumption link in the system. In this paper the load rate classification method (LRCM) is firstly adopted to statistical analyze water injection stations, which are divided into the owing and over load rate stations. As a result, the owing load rate stations accounts for 83.8%, with a serious phenomenon of the Big Horse Pull A Small Carriage, causing the large-scale backflow in the station, and the efficiency is low, the energy consumption is on the high side. Aimed at water injection stations with different load rate, the methods of reasonable shutting down the pumps, pump replacement, optimizing the transmission ratio and piston size, as well as the speed control technology have been used to make the outlet flow and actual demand reasonable matching. The test result shows that the energy saving technology is well targeted, simple, practical and low cost. The pump units’ efficiency improves obviously, the consumption reduces by 10%, which greatly improve the oilfield economic benefits.