Novel Application of Distributed Temperature Sensing and CT Real-Time Downhole Flow Measurement Tool for Thermochemical Treatments

Abstract

Sandstone formations can be particularly susceptible to formation damage due to organic deposits, fine migration, filter cake and formation minerals. Stimulation methods for these types of formations have typically employed mud acid due to the ability to readily dissolve both formation minerals and contaminants introduced into the wellbore/formation during drilling or remedial operations. However, hydrofluoric (HF) based fluids are corrosive, fast spending and causes formation damage by side reactions precipitations, thereby limiting the efficiency of matrix stimulation treatment. A novel heat generating fluid has been developed as an alternative to conventional matrix stimulation for sandstone formation. The method entails triggering an exothermic chemical reaction in-situ to generate heat i.e. ~>400 °F and localized pressure. Generated heat mobilized near wellbore damage; while the pressure provided lifting energy to flowback the well, therefore, improve well injectivity. Exothermic reactants were subsequently injected via coiled tubing and allowed to soak in the treated wells. The resulting temperature and pressure increase were captured in real-time with distributed temperature sensing (DTS) coiled tubing telemetry. DTS profiling helped in understanding the in-situ exothermic reaction and avoiding post treatment production logging costs. The treatment was executed in different phases while injectivity tests were conducted after each step for each phase evaluation. To prove the stimulation concept using thermochemicals, the treatment was applied in sandstone wells and showed superior results. DTS and downhole flow tool profiling confirmed a homogeneous treatment along the perforated interval of the well. Post treatment results showed improved well injectivity up to 50 times. Attempts to realize consistent performance of the conventional stimulation treatments with different formulations have either been cost prohibitive or relatively ineffective. The non-acidic and heat generating fluid holds promise as an economic and a technical solution to well enhancement issues in sandstone reservoirs.