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Petroleum Science and Technology - Volume:7 Issue: 4, Autumn 2017

Journal of Petroleum Science and Technology
Volume:7 Issue: 4, Autumn 2017

  • تاریخ انتشار: 1396/10/04
  • تعداد عناوین: 8
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  • Yanfeng Liu, Yuetian Liu, Lu Sun, Jian Liu Pages 3-12
    The features of bad flow unit continuity and multiple layers emphesize the importance of a well pattern design for the development of a fluvial-delta reservoir. It is proposed a method to predict well pattern connectivity (WPC) based on the exploration and evaluation of wells. Moreover, the method helps evaluate the risk of well placement. This study initially establishes the parameters for characterizing the lateral and vertical flow unit distributions. Then, extensive statistics on the mature oil-field sands of synthetic geological models are obtained to generate the prediction model of WPC which will reveal the correlation among WPC, flow unit distribution, and well spacing (WS). Finally, a case study is conducted to validate the proposed method for predicting WPC. The procedure of the method is comprised of two steps. The first step is to calculate the parameters which characterize the vertical sand body distribution of the target formation by using the well drilling and logging information. The second step is to integrate the calculated parameters and designed WS into the proposed formula to forecast WPC. The new method of WPC prediction has the advantage of integrating the static and dynamic information of similar mature oil fields with each other. By utilizing the model, making an important decision on well pattern design and a reservoir production forecast in the newly discovered continental fluvial-delta reservoir would be reasonable.
    Keywords: Well Pattern Connectivity, Flow Unit Distribution, Well Spacing Optimization, Reservoir Performance
  • Vahid Azamipour, Mehdi Assareh Pages 13-31
    This paper introduces an effective production optimization and a water injection allocation method for oil reservoirs with water injection. In this method, a two-stage adaptive simulated annealing (ASA) is used. A coarse-grid model is made based on average horizon permeability at the beginning iterations of the optimization to search quickly. In the second stage, the fine-grid model is used to provide the accuracy of the final solution. A constrained optimization problem to maximize an objective function based on net present value is implemented. Allocation factors from the streamline simulation are used to help for the appropriate estimation of initial water injection rates. The proposed optimization scheme is used for a field sector simulation model. The results show that the optimized rates confirm the increment of total oil production. Optimized oil production and total water injection rates lead to an increase in the total oil production from 385.983 (initial guess) to 440.656 Msm3. This means a recovery factor increment by 14.16%, while the initial rates were much higher than the optimized rates. Moreover, the recovery factor of optimized production schedule with an optimized total injection rate is 2.20% higher than the initial production schedule with an optimized total water injection rate. The allocation of the water injection rates and the revision of allocation rates result in 446.383 and 450.164 Msm3. The revision of the water rates allocation provides a reduction of water cut during production.
    Keywords: Life-Cycle Optimization, Adaptive Simulated Annealing, Water flooding, Streamline Simulation
  • Mingjun Li, Ma Yongxin, Yi Xiangyi Pages 32-40
    Inflow control devices (ICD), which prevent water breakthrough by controlling the inflow profile of a well, have been used successfully in many oilfields. This paper will introduce a new discovery and an unsuccessful example. Moreover, this paper investigates meticulously and thoroughly to find the application conditions of the new discovery. Based on permeability rush coefficient and permeability differential, a series of plans are carried out to study ICD application conditions. Finally, a new discovery is developed. There are inflow-control device applications for ICD’s, which can work well in heterogeneous reservoirs for controlling water and increasing oil production, but they cannot work well in a homogeneous formation. The effect of ICD on controlling water and increasing oil is very sensitive to the degree of reservoir heterogeneity. The cumulative oil production increases with increasing permeability rush coefficient and permeability differential.
    Keywords: Inflow Control Devices, Controlling Water, Increasing Oil Recovery, Application Conditions
  • Mohammad Reza Talaghat, Ahmad Reza Bahmani Pages 41-53
    In this work, a mathematical model is established to describe the removal of CO2 from gaseous mixtures including CH4 and CO2 in a polypropylene hollow fiber membrane contactor in the presence of conventional absorbents such as monoethanolamine (MEA), methyldiethanolamine (MDEA), and a blend of them. Modeling was performed in axial and radial directions under the fully-wet condition for countercurrent gas-liquid flow arrangement. Both of axial and radial diffusions have been considered in three segments, including shell, membrane, and tube. To evaluate the model, the results of this model were compared with the experimental data and the results of COMSOL software and the results were in agreement with the experimental data and COMSOL outputs. In addition, the effect of various parameters on the removal percentage of carbon dioxide from gas mixtures was studied. It was found out that the CO2 removal percentage is the best by using MEA solution as the absorbent. This modeling shows that the removal of CO2 increases by adding MEA into MDEA solution. In this study, the factors that influence the removal percentage of CO2 from gaseous mixture were investigated. The CO2 removal efficiency increased with an increase in the liquid flow rate, number of fibers, membrane length, porosity-to-tortuosity ratio, and solvent concentration. The results show that increasing gas flow rate reduces CO2 removal due to decreasing the contact time. Finally, the performance of this membrane was compared with other membranes such as polyvinyl difluoride (PVDF) and polytetrafluoroethylene (PTFE). The results show that the percentage of CO2 removal by the polypropylene HFM is higher than that of the PVDF and PTFE hollow fiber membranes in the presence of MEA as the absorbent.
    Keywords: Hollow Fiber Membrane, CO2 Removal, Separation, Modeling, Blend of Amines
  • Zhang Jun, Zeng Jia Pages 54-64
    During the flood development in an oil field, the creep characteristic of mudstone is one of the important factors causing casing damage. In this study, based on the theory of fractional order differential and taking into account the creep damage evolution rules, a fractional nonlinear creep-damage model is proposed to reflect the instantaneous deformation in loading processes and the accelerated creep stage of mudstone. After assuming that the relationships between strain and time can be expressed by the exponential functions, the creep-damage constitutive model to describe the relationship between stress and strain stress of mudstone is established under the condition of accelerated strain rate loading. Furthermore, uniaxial creep tests and conventional triaxial compression tests were carried out to validate the proposed model. It is found that the fractional nonlinear creep-damage model can effectively describe the characteristics of the three stages of mudstone creep; moreover, this model can reduce the number of components and the parameters. Both the fractional nonlinear creep model and the creep-damage constitutive model have a high fitting relationship with the test results. Also, the initial elastic modulus and confining pressure are in a good linear relationship. Finally, the parametric sensitivity analysis of the theoretical model is carried out. The correctness and applicability of models were confirmed from three respects of the derivation process, test results, and the theoretical analysis.
    Keywords: Fractional Calculus, Stress-Strain Relationship, Damage Mechanics, Mudstone Accelerated Creep
  • Ehsan Khamehchi, Seyed Arman Hosseini Kaldozakh, Ali Alizadeh Pages 65-76
    In oil industries, water injection into oil reservoirs for pressure maintenance, oil displacement, and oil recovery is a common technique. Formation damage during water injection is a major problem in this process. Formation damage from the incompatibility of formation water (FW) and injection water (IW) causes a reduction in the permeability around the injection wells. Therefore, it is necessary that the formation damage be minimized using specific techniques such as the injection of scale inhibitors and water compatible with formation water. It has been proven that moving water through relatively weak magnetic field changes water properties. These changes involve density, electrical conductivity, salts dissolving ability, sedimentation rate of solid particles etc. This study was conducted to investigate the effect of magnetized water injection on the decline in rock permeability. Therefore, a magnetic field device was designed and combined with a formation damage setup. The results indicate that, in the presence of magnetic field, water injection causes less damage to rock, and the permeability reduction in this case is lower than when non-magnetized water is injected. In addition, the results show that a higher magnetic field flux reduces the permeability damage.
    Keywords: Formation Damage, Water Injection, Magnetized Water, Scale Precipitation
  • Jiang Ping, Zhang Lei, Ge Jijiang, Zhang Guicai, Yuan Yufeng, Wang Yang, Pei Haihua Pages 77-90
    Investigating multi cyclic gas (N2 and CO2) huff and puff have been conducted by long sandpack simulations with four different crude oils from Jiangsu oilfield. According to the production differential pressure and the production regularity during huff and puff, the production process was divided into three sections; the first one is free gas production section; the second section is low viscous oil production section, and the third one is gas driving exploitation section. According to the results, the production decreases with the increase of cycle times at a certain backpressure, and the effect of multi-cycle huff and puff is improved as the backpressure decreases. In the same cycle, the oil production increases as the backpressure declines. In the first huff and puff cycle, positive synergistic effects are generated while CO2 and N2 are being mixed, and there is an optimum ratio between them. The amount of CO2 in the optimum ratio increases as the backpressure rises. The effect of single gas is better than that of mixed gas in multi-cycle huff and puff, and the effect of CO2 is better than that of N2. The effect of huff and puff is not influenced by the injection mode. At a high backpressure, the huff-and-puff effect becomes better as the oil viscosity increases, but at low backpressure, it becomes worse with an increase in oil viscosity. The huff-and-puff effect also gets worse as the temperature rises. The oil recovery degree is improved as the CO2 injection amount increases, but there is an optimal oil exchange ratio. The depressurization process should be neither too quick nor too slow in the CO2 huff-and-puff process. The cyclic oil production is improved with the increase of injection rate while the average injection rate is lower than 90 L/min. The equilibrium time of CO2 is shorter than that of N2. The economic return of N2 huff and puff is better than that of CO2 at high producing pressure drop, and light oil has higher economic returns than heavy oil.
    Keywords: Depressurization, Free Gas Production, Huff-and-Puff Effect, Injection Mode, Oil Reservoirs
  • Liu Jun, Wang Wei, Liu Qing You, Zhang Jian Zhong, Xiao Guo Hua, Sang Guo Pages 91-101
    Water injection strings in highly deviated wells are subjected to complex forces on the string bore. In this work, a mechanical model is developed for these forces and for those on downhole tools. On the basis of this model, and taking account of the characteristics of the string in different working conditions, a temperature field model and a pressure field model are introduced, and a statically indeterminate structural calculation method is adopted. A force tester for highly deviated wells is developed and used in eight tests on strings in the Jidong Nanpu oilfield making a comparison between the measurements from the tests and the results of calculations using the mechanical model indicates that the mechanical model exhibits high computational accuracy, with the errors at the wellhead being no more than 10%, and that the forces on packers calculated from the model are in accordance with those measured in the tests. Thus, the mechanical model developed in this work is suitable for analyzing the forces on water injection strings and downhole tools in highly deviated wells.
    Keywords: highly deviated well, water injection string, packer, mechanical model, mechanics experiment