Advanced Materials Research Vol. 402

Abstract: With the tailings dam reinforcement project newly built in Yakou as the example and limit equilibrium horizontal slice method as the methodology, this paper has researched the feasibility of applying geosynthetics in fine tailings dam reinforcement. The results from limit equilibrium horizontal slice method show that the stability of reinforced tailings dam with geosynthetics increases by 14~17%; while results from numerical simulation method show that the principal stress vector direction and the principal displacement vector direction of the dam body can be changed to be favorable to the stabilization of dam by using geosynthetics to reinforce the tailings dam.

Abstract: CO₂ injection has been an important enhanced oil recovery method adopted at the later stage of oilfield development, and a series of studies and field experiments has been done in recent years. However, there are some problems in this process, such as viscous fingering, gravity override, channeling of CO₂ in heterogeneous reservoir. These challenging issues are closely related to the CO₂ injection ways. At present, it is at development stage and calls for more research on optimally choosing CO₂ injection methods to displace oil. This research mainly uses different CO₂ injection methods to displace oil, in order to optimally choose the CO₂ injection method that fit this experiment area, and does research on the effects and principles of CO₂ drive to enhance oil recovery. Compared with gas flooding and WAG, CO₂ foam greatly reduce the mobility of the injected gas and expand the sweep volume. This is consistently observed in the numerically simulated foam process at the field level.

Abstract: Due to the existing fine copper concentrate particles in the thickener overflow which can’t be reused, the water and copper resources have been wasted for a long time. In this study, the combination of coagulant (PAC and PAFC) with flocculant (N83376) were used to enhance the process of sedimentation of copper concentrate pulp, and the results of the above were compared with those when coagulant and flocculant was used alone. It is suggested that PAC and PAFC were both effective with the combination of N83376, however, excess of PAFC resulted in dispersion of particles. Therefore it was feasible to select PAC and N83376 as final combined reagent. The effectiveness of the coagulant and flocculant were evaluated based on the turbidity and the removal rate of suspended solids (SS) of the supernatant. It can achieve 17.03NTU of turbidity and 94.82% of SS removal rate with 750g/t PAC and 1.25g/t N83376, at pH 9~11. The results of filtration test indicate that the performance of copper concentrate pulp after coagulation-flocculation was improved. The filter rate was 0.45 ml/s faster than without reagent, and the water content of filter cake also decreased 1.84%.

Abstract: Characteristics and reasons of particles migration in low-permeability gas reservoirs are studied in this paper based on indoor experiments. In order to control the migration of clays, applying effect of two clays stabilizing agents compared and analyzed. The results show that particles transportation and blockage is a serious damage fact of which producing pressure differential is the main reason in low-permeability gas reservoirs. Stabilizing agents can effectively control the expansion and diffusion of clays, but the effect on fine silt is limited.

Abstract: A series of electric analogy experiments are designed based on the water and electricity similarity principle and frictional pressure drop in wellbore. The contribution of every branch of the multi-lateral well on oil production and the impacts of the number and the angle of branches on productivity has been studied. The results show that the productivity increases as the number and the angle of branch increases, but the increasing tendency slows down. The interference between the horizontal hole and the branch on the side with fewer branches is less than that of the other side. Experimental results provide the basis for optimizing morphology of the branch wells.

Abstract: Mining has a nearly relation with the development of our country and people’s life, in order to improve the informationization of the mining, in this study, realize modeling the objects of the mining by dividing them into four parts, point, line, surface and body models, according to the characteristics of the ground environment and the types of the entities in the mining area. Then, study the methods and realize the modeling and visualization of the ground scene of the mining area by using the technology, ArcEngine, ADO and three-dimensional model. By verifying, this method has better simulation results.

Abstract: The Jabung oilfield in Indonesia is characterized by complex geological structural movement, large tectonic stress and high temperature gradient. Accidents such as borehole collapse and sticking were frequently encountered when drilling shale formations, which often result in serious damage. In this paper, a series of experiments were conducted to evaluate the performance of shale in drilling fluid, including linear expansion rate evaluation tests and rolling recovery evaluation tests. Also X-ray diffraction was used to analyze the mineral composition of shale. The mechanical parameters of shale were obtained through statistical analysis. By using ABAQUS software, the temperature difference induced by thermal stress distribution was analyzed. After that, the borehole stress distribution was determined by coupling the additional stress with in-situ stress. Finally, based on borehole stability mechanical models, the effects of well trajectory on borehole stability were analyzed. We found that the chemical properties of drilling fluid, wellbore trajectory and temperature has a great influence on wellbore stability, and the impact of temperature changes and of well trajectory are the largest factor.

Abstract: Kuche depression of Tarim Basin went through tectogenesis many times, due to the southward thrust compressional stress from Tianshan fold uplift, the geology condition of this area is extraordinarily complex, there are problems such as depth difference in geological horizons, abnormal pressure formations and irregular distribution of special lithologies, etc. All of these problems have brought even more difficulties in engineering design and construction. Accidents such as well leakage, drilling sticking and complex situations happened frequently. All of those have influenced the engineering progress seriously and lowered the actual effect of drilling. In order to resolve the problems and complex situations above, we did detailed researches on accidents in the Kuche piedmont belt of Tarim Basin and studied reasons for complex situations, and then we proposed engineering resolutions and evaluated them.

Abstract: Expandable screen called slotted base pipe functions as skeleton structure in expandable screen. The expansion process is very complicated due to the existence of slots on slotted base pipe and contact friction between expansion tools and tubular. In this work, based on elastic-plastic mechanical analysis of the expandable slotted tube in expansion process, the 3D nonlinear finite element analysis model of contact process was built. Aiming at two specifications of 4-1/2 and 6-5/8 inches 316L stainless steel slotted tubular, expansion deformation process at room temperature with expansion ratios of 25-35% range was simulated. With those works, it hopes to provide a useful foundation for the formulation of expansion technology of expandable screen.

Abstract: In view of actual conditions that AutoCAD is widely used in coal mines in China, the concrete method based on CASS software is intruduced, which can realize the visual prediction and analysis of mining subsidence. Because CASS software has been developed based on AutoCAD, when the digital mining map of CAD format is used, the switchover of data format is not required, and the input, output and edit of the digital mining map is very convenient. The displacement and distortion information of mining subsidence forecast can be represented in the digital mining map by means of the visual graph, which can easily analyze and evaluate mining subsidence. Using the visual method, the efficiency and accuracy of technical decision can be enhanced, and it has practical significance for the mine planning and design and the prevention and control of mining subsidence.