Formation consolidation is a form of sand control that was used extensively in the past, but has been largely replaced by mechanical systems, such as gravel packs or expandable screens. This change has arisen because of a level of uncertainty regarding effective chemical placement and reliability. Challenging economics in the petroleum industry began to make alternative completion techniques more attractive for remediation applications, for developing and producing by-passed reserves behind blank pipe, and for completing marginal reservoirs. Low-cost completion alternatives are actively being sought for both injectors and producers.
To understand the performance of various consolidation options, a series of tests was performed on samples of Castlegate sandstone, incorporating actual perforating operations in the lab to evaluate both treatment placement and performance under reservoir conditions. This paper provides details about the testing process that was used, as well as comparative results for various consolidation technologies, including curable and non-curable agents resulting in various degrees of cohesion between formation particulates. Post treatment evaluations included flow testing single and dual phase fluids under in-situ conditions, as well as post mortem evaluations of chemical placement and mechanical properties.
Section IV perforation flow testing provided a realistic modeling technique to understand the effectiveness of a consolidating agent with respect to its placement or coating behavior, which in turn directly affects the resulting strength and retained permeability after chemical treatment. Results from the flow testing indicate that a critical strength is required to lock the treated sand in place and to overcome the drag force generated by flow. Depth of treatment penetration into the formation matrix is a function of treatment volume, pressure drop, and permeability. The amount of consolidating agent coating on the sand and the resulting strength depend on the concentration of the agent in the treatment solution. With efficient strength as a result of the consolidating agent treatment, only a small quantity of sand was observed to produce from the treated perforation, either with single or dual phase fluids, when compared to a much larger amount of sand produced from the perforation that lacked treatment, even when the perforation was subjected to a lower flow rate.