Chemical Solution Mitigates Stuck Inflow Control Devices (ICDs) in Horizontal Completion

Abstract

Abstract Horizontal open holes covering long reservoir sections can be benefitted by installing inflow control devices (ICDs) along the lateral to even the production contribution from the entire heterogeneous permeability profile. During the drilling and completion process, the well can be shut in for prolonged periods of time. Though the ICDs are designed to withstand the buildup of debris, they are still subjected to the accumulation of weighting and bridging materials existing in the drilling fluid, such as calcium carbonate (CaCO3). This debris deposits on the internal diameter of the valves or the flow control device, preventing proper shifting against the seats, or blocking the flow path of the devices. Recovering the function of the ICDs requires a chemical treatment. In high permeability formations, it is undesirable to have acid contact the rock to compromise the mechanical integrity of the formation or trigger further solids buildup in the ICD's. Therefore, an acid designed to dissolve the solid deposits on ICDs but not penetrate the formation is required. In this study, a modified coreflood setup was designed and an acid-based chemical treatment was formulated to remove solid deposition on the ICD. The goal was to dissolve the calcium carbonate scale on the ICD with minimal penetration into the formation to avoid formation softening. The core assembly simulates the geometry of the ICD completion system with core matrix behind the ICD operating space. Calcite marble was used to represent the scale deposited on the ICDs, while Indiana limestone was used to represent the reservoir rock. Several acid formulations were tested using the custom designed coreflood setup. One acid blend composed of a strong organic acid mixed with hydrochloric acid (HCl) and a second blend of HCl and mutual solvent showed the desirable effect of dissolving the scale deposits (calcite marble in this case) with minimum to no penetration into the formation matrix. The success of the two acid systems in dissolving calcium carbonate deposits on the ICDs was confirmed by analyzing the pressure data during the core flooding experiment, as well as from analyzing the post-treated core samples using X-ray tomography. Simulation of completion design in the laboratory is a key factor to test and design acid treatments to overcome scale problems in the field. Single phase acid systems containing no gelling or emulsifying agents were tested and proved capable of dissolving the solids deposited on the ICDs with minimum formation contact. This will result in an economical and easier one-step treatment in the field, avoiding the complexity encountered with pulling the whole completion string out of the wellbore to be treated with acid, then reinstall it back into the well.