Use of Combined Analytical and Numerical Sand Production Prediction Methods to Define Simple Cut-Off for Sand Control and Well Completion Selection

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ABSTRACT: There are several sanding prediction techniques commonly used by well engineers and geomechanics specialists. The most desirable ones are empirical models with simple rules but these need a vast amount of field observations and historical production data to derive the appropriate cut-offs. We introduce a geomechanical workflow in which field-calibrated geomechanical models are used to define simple cut-offs, e.g. rock porosity or strength, for sand production using a combination of advanced analytical and numerical sanding models. These simple cut-offs are then incorporated in decision flowcharts to assist well engineers for completion and sand control decisions considering well-life sanding risks by following a quick, cost-effective and holistic approach. Pros and cons of pragmatic cut-offs are listed and the residual risks involved with such approaches are also highlighted. The workflow is shown in a gas field and the validity of the workflow and sand control decisions are confirmed after several years of production. 1. INTRODUCTION Sand or solids production, also called sanding, along with hydrocarbon, water and scales is a natural component of production systems in oil and gas wells. The root cause of sanding is failure of formation rock around the wellbore due to effective in situ stresses acting on the rocks exceeding the mechanical strength under production conditions. Sanding is manageable, it can be avoided, mitigated, controlled or handled depending on its timing (i.e. reservoir pressure depletion and bottom hole flowing pressure), interval (sanding zone) and its severity (volume of produced solids, impacts of sanding on well components and well productivity). Essential parts of integrated and holistic sand management practices include; competent sanding prediction which require understanding of field geomechanical conditions, followed by sand control measures for limiting sand production to an acceptable level for both well productivity and integrity, and safety and environmental constraint. It also included consideration of sand handling and monitoring at both the surface and downhole. Sand production prediction studies are an integral part of overall hydrocarbon field development planning so that sanding potentials can be assessed and appropriate completion designs are considered.