Browsing by Author "Dong, Chao"

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    An integrated multi-component reservoir-wellbore thermal model
    (2012) Dong, Chao; Chen, Zhangxing (John)
    As more and more wells have been put into operation, accurate modeling of wellbore flow plays a significant role in reservoir simulation, particularly in thermal recovery processes such as Steam Assistant Gravity Drainage (SAGD) and Cyclic Steam Stimulation (CSS). The main objective of wellbore modeling is to predict heat exchange and phase behaviour in the vertical and horizontal wellbores and therefore to predict their effect on the entire simulation process. Coupled reservoir and well modeling can provide a detailed description of these thermal processes. To model these processes, a thermal K-value multi-component reservoir model is developed. This model has the ability to simulate three-dimensional multi-component, three-phase thermal processes such as SAGD and CSS. Two corresponding sets of wellbore models, Sink/Source Well (SSW) and Multi-Segment Well (MSW) models, are developed and tested to achieve several result. The SSW model consists of a set of well control methods. It is chosen as the reference wellbore model in this study and validated with commercial software. In this study the MSW model is also constructed and tested for several thermal recovery processes. The MSW model includes mass and energy conservations for each component, constraints and a general pressure drop relationship. The multiphase wellbore flow is represented using a no- lip or slip model. It has the ability to deal with complex configurations such as multi-tubing situation; several reults are included in the thesis. Three type of coupling schemes for the MSW model are also tested and compared in this research: full, iterative or advancing-level coupling to the reservoir. In addition, An algorithm of dynamic gridding for solving a wellbore flow model is coupled with the General Propose Reservoir Simulator (GPRS), which has the capability to simulate the isothermal black oil reservoir model to obtain detailed information on such important quantities as flow pattern and mixture velocity in any specific location of wellbore. We apply the black oil model to the simulation of several cases on dynamical local mesh refinement isothermally, and compare the results with fixed coarse and fine meshes. The experiments demonstrate that the algorithm can yield accurate results with acceptable computational time.
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    ItemOpen Access
    Development of a Thermal Wellbore Simulator with Focus on Improving Heat Loss Calculations for SAGD Steam Injection
    (SPE Reservoir Evaluation & Engineering, 2016) Chen, Zhangxing (John); Xiong, Wanqiang; Bahonar, Mehdi; Dong, Chao
    Typical thermal processes involve sophisticated wellbore configurations, complex fluid flow and heat transfer in tubing, annulus, wellbore completion, and surrounding formation. Despite notable advancements made in wellbore modeling, accurate heat loss modeling is still a challenge using the existing wellbore simulators. This challenge becomes even greater when complex but common wellbore configurations such as multi-parallel or multi-concentric tubings are used in thermal processes such as Steam Assisted Gravity Drainage (SAGD). To improve heat loss estimation, a standalone fully-implicit thermal wellbore simulator is developed that can handle several different wellbore configurations and completions. This simulator uses a fully implicit method to model heat loss from tubing walls to the surrounding formation. Instead of implementing the common Ramey method (1962) for heat loss calculations that has been shown to be a source of large errors, a series of computational fluid dynamical (CFD) models are run for the buoyancy driven flow for different annulus sizes and lengths and numbers of tubings. Based on these CFD models, correlations are derived that can conveniently be used for the more accurate heat loss estimation from the wellbore to the surrounding formation for SAGD injection wells with single or multiple tubing strings. These correlations are embedded in the developed wellbore simulator and results are compared with other heat loss modeling methods to demonstrate its improvements. A series of validations against commercial simulators and field data are presented in this paper.