Novel Sandstone Stimulation Using Thermochemical Fluid: Successful Field Application

Abstract Sandstone acidizing is implemented to remove the damage from the near-wellbore region. Different techniques are used to remove the formation and damage and improve reservoir productivity. This paper presents a novel sandstone stimulation technique using thermochemical fluids. The used chemicals are not reactive at surface conditions and react only at the downhole conditions. The reservoir temperature or pH controller can be used to activate the chemical reaction. A successful field application of the proposed method is reported in this paper. Different measurements were conducted to assess the performance of the new technique. A compatibility study was conducted at different conditions to evaluate the generation of acid foam. Also, Coreflood experiments were performed by injecting the foam generating solutions into tight sandstone cores. The rock permeability and the pores network were evaluated before and after the chemical injection. Scanning electron microscopy (SEM) and nuclear magnetic resonance (NMR) and analyses were performed. Moreover, a field application of the in situ acid foam generation was conducted. The treatment was implemented by injecting the solutions to react at the downhole conditions and improve the well injectivity. The profiles of injection rate, circulation pressure, and total volume were monitored during the field treatment to assess the treatment performance. Results showed that the used solutions can generate foam in less time and the volume of the generated foam is around 30 folds of the original chemical volumes. The in situ generated foam can penetrate deeper in the reservoir due to the larger foam volume compared to original chemicals, leading to improve treatment efficiency. Also, the new technique increased the rock permeability from 0.6 to 420 mD due to the dissolution and removal of illite minerals as well as the generation of micro-fractures due to the pressure pulses. The field application showed a very successful performance and the well injectivity was increased by 18 times after the treatment. The proposed technique utilizes thermochemical fluids to generate acid foam at the reservoir conditions. This technique can eliminate all the risks associated with HSE concerns, in addition to the corrosion issues. Also, the proposed treatment showed a successful field application and increased the well injectivity up by 18 folds of the original injectivity.