An Integrated Geomechanical and Passive Sand-Control Approach to Minimizing Sanding Risk From Openhole and Cased-and-Perforated Wells

Abstract

Summary The source of sand production is the presence of disintegrated sand grains caused by rock failure at the wellbore and/or perforation walls. Decision for appropriate sand-control strategy requires engineering analysis to evaluate timing and severity of sanding over the life of field conditions. Optimizing well parameters such as well trajectory, perforation orientation, and level of drawdown using geomechanical principles can minimize and delay sand production. This paper presents a geomechanical modeling approach that integrates production history with information from drilling data, well logs, and rock-mechanics tests. A gas field in south Asia with 11 wells and several years of production experience is used to demonstrate this approach. Core-calibrated rock-strength-log profiles are estimated throughout the reservoir depth for all existing wells. A rock-failure criterion at the sandface is developed as a function of in-situ stresses, rock strength, well trajectory, perforation orientation, reservoir depletion, and drawdown. Sanding-evaluation results are calibrated and verified with production data and evidence of sanding in existing wells. Sand-free operating envelopes and sand evaluation logs are then generated for all existing wells and planned infill wells for the life of field conditions. Sand-prone zones and timing of sanding are established as a function of depletion and drawdown for each well, using production forecasts for the rest of field life. For new infill wells, optimum well trajectories, selective perforation intervals, and optimum perforation orientations are proposed to minimize and delay sand production. Recompletion and using passive sand-control methods including selective and orientated perforations are recommended for a number of existing wells. This paper is expected to provide well engineers with guidelines to understand the principles and overall workflow involved in sand-production prediction and minimization of sand production risk by optimizing well trajectory, perforation orientation, and selective-perforation strategy.