An optimization design criterion for multistage transversely fractured horizontal wells using fractured convergence skin

  • Olayiwola Saheed Olawale

    Student thesis: Master's Thesis

    Abstract

    Over the last two decades, the demand for the energy worldwide had increased which had led to the increase in price of the hydrocarbon which is the major source of energy. However, the discovery of gigantic conventional reservoirs had reduced which has led to the dependence on the current reserves to meet the demand. Increase in the price of crude oil had led to the increase in activities of research and development with an objective to break through the assessment of unconventional resources. Fracturing has been proven to be one of most the viable means which can be easily used to access the available resources in unconventional tight reservoirs. Thus, evaluating the production rate after the end of fracturing job is necessary to determine the economic viability of the recovery. Inaccurate evaluation of the post-treatment can lead to either overestimation or underestimation of the production rate. The objective of this thesis is to account for the variation of the simulation model from the field data. This work has reviewed the flow behaviour occurring in a transversely fractured well from the boundary of the reservoir to the toe of the wellbore. It was concluded that a skin occurs at every point in the junction of the fractures and the horizontal well which can account for the wide variation of the simulation model from the field data. This skin has a cumulative effect on the production rate of the transversely fractured well. Thus, a positive skin may have resulted from the convergence of the fluid flow in the fracture path to the near wellbore. Therefore, the need to estimate the irreducible skin referred to as fractured convergence skin is necessary to evaluate the production rate. This work has modeled the skin that can occur in the multi-staged transverse fractures in horizontal wells as a function of the fracture conductivity as well as the number of transverse fractures. In addition, it describes the effect of the fractured convergence skin on the production rate by incorporating it into the productivity index. Mathematical analysis using Taylor Series had been used to describe the physics of fluid flow from the fracture into the wellbore. The modeled fractured convergence skin had been incorporated into the productivity index equation to estimate the production rate for a multistage transverse fractured horizontal well. Also, the fractured convergence skin was integrated with all other optimization design parameters to estimate the productivity index and to determine the optimum horizontal well length with optimum number of transverse fractures for the reservoir. Treatment design for a transversely fractured well had been modified by incorporating the modeled fracture convergence skin together with the effect of the horizontal well length to determine the optimum number of transverse fracture which will give optimum economical production rate. This work had found the compromise between the optimum point of the horizontal well length and the optimum point from the economic point of view. This will lead to an increase in accuracy of the design estimation. Finally, the model had been applied to a hypothetical field formation which has properties similar to the Arab peninsula formations in order to evaluate the application of this project to the UAE formation. The economic analysis of the project was evaluated with the available data to determine the optimum design parameter.
    Date of Award2013
    Original languageAmerican English
    SupervisorMD Rahman (Supervisor)

    Keywords

    • Applied sciences
    • Fractured convergence skin
    • Horizontal oil well drilling.
    • Hydrocarbon
    • Multistage
    • Optimization design criterion
    • Petroleum engineering
    • 0765:Petroleum engineering

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