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.

Estimation of Sand Production Rate Using Geomechanical and Hydromechanical Models

“…Equation (1) considers effect of reservoir pressure decline [9] which can be accounted for by updating in situ stresses, while the vertical stresses are usually kept constant: Figure 10 we also present the CBHP when the UCS changes. For example, for UCS = 1950 psia, if reservoir pressure is 6000 psia, the CBHP is about 1500 psia; if the bottomhole pressure is lower than this value 1500 psia, sand production will occur.…”

Geomechanical and Reservoir Integrated Hydraulic Fracturing Optimisation for a Tight Oil Reservoir: A Case Study from Offshore Vietnam

“…There are finite element and analytical approaches for sand production prediction. Details of the analytical method used in this study can be found in Rahman et al (2010). A calibrated log-based UCS profile in sandstones was created using acoustic log data.…”

Geomechanical Evaluations Helped Successful Drilling Operation and Completion in Mature Fields with Depleted Reservoirs Interbedded with Weaker Formations

“…DST, sand influx test, actual production data, etc.). Further mathematical and applied details of the model including determination of the maximum effective stress are presented in Rahman et al (2010).…”

“…A TWC value of 4,750 psi was chosen for the sanding evaluation using the linear elastic method (theoretical and applied details can be found in Rahman et al, 2010 andKhaksar et al, 2008). The 4,750 psi TWC is even less than P05 TWC of ~6,000 psi.…”