On physical reliability of constitutive relations in plasticity for plane processes with bend point

Abstract We focus our attention on the physical reliability of plasticity at complex loading. It is important for reliable solution of boundary-value problems. The results of experiments on complex loading in the form of trajectory in the form of two-element trajectories for weakly hardened material are considered in this issue. An analysis of physical reliability of the simplest versions of plasticity theories for describing active processes of complex loading with bend point is given here. We provide analysis and recommendations as to preferable applications of classical theories for plane complex loading modes. It is shown that neglecting the loading process geometry lead to considerable errors in theoretical calculations.</jats:p

Case-study of Succesful Pilot Polymer Flooding in the South Turgay Basin's Oilfield

AbstractThis paper outlines implementation results of pilot polymer flooding project in the South Turgay basin's field in Kazakhstan. During pilot injection, production data and main parameters were gathered and analyzed.In the paper contains description of general information about selection of the appropriate reservoir area, including geology, water quality and other main parameters for the best polymer selection. Based on screening of these parameters an area was selected for pilot polymer flooding implementation. Polymer flooding carried out using two injection wells.After continuous injection, according to injection protocol, initial watercut decreased in the oil production of producing wells due to improvement in the reservoir sweep efficiency caused by flooding. Bottomhole pressures and injection rates in the injection wells varied insignificantly. Oil production increased comparing with the standard water flooding process that was applied initially.Oil production was monitored and analyzed by Operator Company since the begging of the injection. Production history from the beginning of pilot polymer flooding project demonstrates efficiency of this EOR method. Considering positive results of this injection stage Operating Company plans to continue polymer solution injection in the next stages of the field developmet.</jats:p

Applying of the associative polymer solutions to enhance oil recovery

Abstract Purpose of this report to inform the petroleum readership of recent advances in areas of the associative polymer flooding. Polymer flooding is the industrial enhanced oil recovery method, which successfully has applied in various types of reservoirs. The polymer flooding for high-temperature and high-salinity reservoir faces enormous challenges. Hydrolyzed polymer has been used as the main polymer type for the polymer flooding. Now researchers have turned their attention to associative polymer solutions. This report presents an overview of the associative polymer flooding. Some recent projects have shown an expanding technology. This report reviews published results of the use of associative polymers to enhance oil recovery in recent years. The associative polymer flooding is one enhanced oil recovery (EOR) method being developed recently to increase the oil supply. Polymer flooding application in high-temperature and high-salinity reservoirs is currently limited by polymers chemically and thermally degradation at high temperature and salinity. The associative polymer solutions improve the over-all reservoir conformance by providing mobility control. Water is injected after the polymer solution. Based on the number of new laboratory and pilot tests, field activity is continuing at a moderate level.</jats:p

Upgrading of the recording system of complex loading testing machine

The effectiveness of experimental studies of the mechanical properties of materials and the reliability of the results obtained are determined by the technical level of testing machines. The stress-strain state of the object is monitored using recording sensors. The reading accuracy for the existing CL unit is 8%. However, this accuracy appeared insufficient when studying the developed plastic deformations. The problem of insufficient accuracy is partially related to the outdated recording system of the experimental setup, both when taking the results of the experiments and when managing the experiment. Getting of the reliable data upon complex loading is necessary to identify the reserves of the bearing capacity of structural elements in conditions of multi-parameter loading. All the experiments on a CL testing machine were carried out at room temperature. An additional amplifier of the electric signal of the strain gauge sensor was introduced to improve the accuracy of the readings of the recording system. The results of modernizing the recording system of the CL testing machine intended for static isothermal tests of tubular specimens are presented. The testing machine provides testing of the samples under axial tensile force and torque.</jats:p

To the stability of the roadbed reinforced with gabions

Abstract Mountain and foothill regions of Uzbekistan in the winter-spring period are the subject to erosion as a result of precipitation and mudflows. This fact led to the beginning of their strengthening with gabion structures. Gabions also improve the operation of the entire structure under the dynamic influences’ action, including the seismic ones. In the work, research and testing in the laboratory and field conditions of the erected gabions effectiveness in road construction in the Parkent district of Tashkent region. The analysis of the gabion structures main structural parameters’ influence to strengthen the subgrade on their stability and deformability has been performed. Reinforcement of the road subgrade 4P187 “Kiziltof sh. - Parkent sh. (59 km) - Kumushkon” was performed with box-shaped gabion structures. This road stretch from the stake PK80 to PK90 was blurred as a result of mudflow. To strengthen this slope, a local program for its targeted strengthening has been approved. As the initial conditions for the considered site survey, the work to determine the physical and mechanical properties of soils lying in the road slope has been carried out.</jats:p

Numerical modeling of the problem of indentation of elastic and elastic-plastic massive bodies

Abstract The paper considers the dynamic pressing-in indenter in a plane elastic-plastic statement. A general statement of the problem of a rigid body under a flexible stamp pressing-in is given; it allows considering the elastic and plastic properties of the material and the process of the stress-strain state formation. The problem of a flexible stamp action on the outer boundary is realized using the finite-difference method. By solving the problem for a quadrangular profile, the distribution of the stress-strain state of the body under consideration and the formation of stresses over time are shown. The effect of plastic properties of the material on the stress state of the body is assessed by comparative analysis.</jats:p

To numerical approach for calculation of underground structures

Abstract The new approach for numerical calculating of stress and strain state of underground structures is presented in this issue. The advantage of this method is using in design scheme a real diagram of concrete and reinforcement materials. Also, these calculations are allowed to trace the process of deformation of reinforced concrete in each of the sections of the structure. In the technique, static calculations of reinforced structural elements when changing their initial conditions or stress state after strengthening are carried out taking into account new data. A three-dimensional finite element calculation is also carried out while taking into account regulatory loads. Assessment of levels of tangential and tensile stresses in walls makes it possible to target reinforcement and parameters of monolithic stiffness belts. Numerical results for discussion are presented in this paper.</jats:p