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Laboratory-Scale Investigation of Rock Mechanical Behavior under Reservoir Condition

Razaghi, Negar | 2021

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 54190 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Shad, Saeed; Pak, Ali
  7. Abstract:
  8. Geomechanics has an immense impact on petroleum engineering and applies to the most aspects of petroleum extraction, from exploration and drilling to production and even reservoir abandonment. Studying the mechanical behavior of rocks in hydrocarbon reservoirs and overburden layers will lead to better characterization of mechanical state of the environment. Therefore, a solid understanding of rock mechanical behavior can play a crucial role in reducing operational issues of oil and gas extraction in different phases and prevent extra cost and time consumption. To illustrate, studies of wellbore stability and integrity, casing burst and collapse, drilling optimization, sand production, environmental issues such as heave and subsidence, and feasibility study of hydraulic fracturing operations are some significant applications of geomechanics in the petroleum industry.In this regard, it is evident that determination of the rock mechanical parameters based on laboratory studies can be considered as a crucial phase of any projects related to the extraction of hydrocarbon fluid from reservoirs. Typically, the mechanical properties of rocks can be obtained using both static and dynamic approaches. In this study, the focus is on determining the static rock’s mechanical properties. The static methods are based on the survey of stress-strain behavior resulting from the direct placement of rock samples under certain stress conditions.Based on the review of the research background, less attention has been paid to laboratory-scale numerical simulation in petroleum engineering compared with other engineering branches. According to the potential of numerical simulation tools and the development of appropriate constitutive models, lab-scale numerical simulations can be considered as efficient, low-cost, and robust alternatives to some expensive and also destructive laboratory tests. Therefore, in this study, the geomechanical behaviors of reservoir rocks under uniaxial and triaxial stresses have been investigated using both experimental and numerical modeling approaches. A new empirical correlation between peak stress, Young’s modulus, and stress condition has been proposed using non-linear regression analysis on experimental results. The analogies between the mechanical response of concretes, rocks, and other brittle and quasi-brittle materials to applied stresses were considered to develop appropriate numerical models; so that prior comprehensive studies on the mechanical behavior of concretes have been used. In this research, numerical models were developed based on non-linear finite element analysis in ABAQUS software, and the concrete damaged plasticity (CDP) model was used as the constitutive model. The uniaxial and triaxial compression tests were simulated, and the validation of numerical simulations has been evaluated compared to laboratory results through the stress-strain curves. The results demonstrate an acceptable agreement between the prediction of numerical simulation of the rock’s response to the applied stress conditions and the result obtained from laboratory experiments. Moreover, based on results of numerical simulations associated with mathematical and theoretical analysis, new stress and strain models have been presented for confined rocks. The current study has been carried out on high-strength reservoir rock samples belong to one of the reservoir formations in Iran. Still, it deserves mentioning here that the proposed procedure can be generalized to other high-strength rock samples
  9. Keywords:
  10. Numerical Modeling ; Nonlinear Finite Element Analysis ; ABAQUS Software ; Numerical Simulation ; Experimental Investigation ; Geomechanical Properties ; Reservoir Geomechanics

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