Newly Developed Aqueous Paraffin Inhibitor Dispersion Provides Flow Assurance During and After Stimulation

Abstract

Abstract A typical challenge encountered during hydraulic fracturing is severe wax deposition on the rock surface inside fractures as relatively cold fracturing fluids encounter hot crude oils in the reservoir. This results in multiple production challenges for operators because either crude oil viscosity increases due to loss of light compounds, or wax deposits clog the effective flow paths from interior of the reservoir to the wellbore. This is of particular concern when the temperature and pressure start to drop rapidly right inside the fractures. In the past, water-soluble surfactant-based wax dispersants have been frequently used to combat excessive wax deposition during frac. Polymer-based paraffin inhibitors, despite being more effective and more soluble in crude oils, however, have not been extensively deployed because they are insoluble in water and incompatible with commonly used frac additives, unless they are encapsulated or adsorbed in substrates. Most importantly, our water-based technology platform makes it possible to combine water dispersible paraffin inhibitors with scale inhibitors, clay stabilizers or surfactants, essentially creating a multi-functional frac additive. This new approach leads to potential logistic savings and reduced carbon footprints. In this paper, a newly developed water dispersible paraffin inhibitor is discussed. This innovative solution allows the product to be fully compatible with most frac fluids, in particular regard to polyacrylamide-based friction reducers. Typical emulsion/sludging tendency, salinity tolerance, pour point, viscosity and cold finger tests, etc. were performed to ensure that the product remains effective and travels in the leading edge of frac fluids under downhole conditions. In a similar mechanism to conventional emulsion-based friction reducers, the aqueous paraffin inhibitor dispersion was tailored to enable rapid phase inversion, releasing active polymer into frac fluids and interacting with waxy oils. Most importantly, it was demonstrated that molecular weight of aqueous paraffin inhibitor dispersion polymer played an important role in dictating its inhibition efficiency against wax deposits, while allowing additional components such as scale inhibitors, surfactants, etc. to be incorporated in the same formulation.