Automated Workflow Mitigates Sand Influx by Determining Minimum Tubinghead Pressure

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 220649, “Automated Sand-Influx-Mitigation Workflow Using Geomechanical Analysis and Minimum Tubinghead-Pressure Estimation,” by Prince Kumar, Upasana Gogoi, and Bhartendu Bhatt, SPE, SLB, et al. The paper has not been peer reviewed. _ The authors describe an automated workflow that helps mitigate sanding caused by excessive drawdown by determining the minimum tubinghead pressure (THP). The automated workflow is designed to autocalibrate, analyze, and recommend actionable measures to control THP to prevent sand ingression. This enables oil and gas operators to control sand production, resulting in production enhancement and fewer workover jobs. Field Background Field A is an onshore gas field producing for over 15 years. With bottomwater drive, no depletion of reservoir pressure was evident. The main reservoir sand, of Oligocene to Miocene age, is weak in nature and prone to sanding. In the absence of a geomechanical study, determining the critical drawdown pressure (CDDP) for the reservoir poses a challenge for sand-free production. The wells were dying out frequently because of choking of perforations from produced sand settling in the well. As a result, frequent workovers were required for continuous flow from the wells. Based on the data availability and feasibility of the solution with respect to utility and functionality of the potential solution, six naturally flowing gas wells from the field were shortlisted for the study. Study Objectives With the aim of developing a digital oilfield solution to calculate minimum THP to be maintained for sand-free production, a workflow was established. The workflow has four major components: 1D geomechanical analysis, sand-ingression analysis, well modeling and autocalibration, and automated THP estimation. Fig. 1 shows the steps followed to develop the sand-influx-mitigation workflow. The output of the overall workflow is CDDP from the geomechanics workflow and minimum THP limit from the well-model-based workflow; the geomechanics part is an offline study and the well-model part features an automated workflow for sensitivity execution. Methodology Geomechanical Analysis. 1D Mechanical Earth Model (MEM) Construction for Wells. The 1D MEM is a set of rock-mechanical parameters, pore pressures, and stresses as a function of depth that can be used to understand and quantify the behavior of subsurface formations when they are subjected to deformation and change in pressure, temperature, and stress. Once an MEM is constructed, it can be used to conduct wellbore-stability and sand-production analyses for drilling and completion. Wellbore-Stability Analysis. Wellbore-stability analysis can be performed to check sanctity and calibrate the 1D MEM. Using the computed rock properties and horizontal stresses, history matching is performed with actual drilling events and observations, such as breakouts or drilling-induced tensile fractures observed in image logs and breakouts interpreted from caliper logs. When the predicted failures and events match with the actual observations during drilling, one can conclude that the 1D MEM is calibrated and represents the subsurface rock-mechanical properties.