Innovative Multifunctional Chemistry to Remove Oil Based Mud Filter Cake and Remediate Near Wellbore Damage Producing Wells After Well Communication

Abstract Drilling fluids are complex mixtures with different base fluids along with a series of additives to deal with specific well requirements. Oil- based drilling mud (OBM) filtration is commonly seen during the drilling stages and its removal is very critical to prevent impact reservoir productivity. Nowadays, exploitation in unconventional reservoirs, the closeness between producing wells and new drilled ones can create communication at reservoir level, resulting in reduction of the productivity index of the impacted parent well due to injected fluid migration. Removal of this induced formation damage can be very inefficient due to the usage of conventional acid formulations or solvents and traditional surfactants preflushes that are barely able to break and remove the existent damages, without actively water wetting the formation. An approach has been developed to eliminate the use of solvent preflushes, using a novel multi-functional chemistry in conjunction with 15% HCl to effectively remove OBM residue and any additional organic and inorganic damages present in the producing well. This innovative approach breaks and removes OBM emulsion damage while improving relative permeability reverting the wettability of the rock from oil-wet to water wet. This work performed (I would change to: This work involved) a suite of laboratory screening tests to evaluate the removal of filter cake and formation damage with the multifunctional chemistry approach in wells drilled with OBM or impacted for well communication. These tests included OBM filter cake clean-up in a high pressure/high temperature cell, dispersibility and reverse of the wettability of the particles, as well as fluid compatibility. Field data from clean-ups application with the multifunctional approach in conjunction with produced fluids samples and results from the laboratory testing, were utilized to validate the multi-functional chemistry performance. A multipackage formulation has been developed, to be fully miscible in acid packages, maximizing the performance of the OBM residual damage removal, and scale dissolution, by effectively de-oiling and penetrating the organic coating layer build-up on calcium carbonate and iron sulfide scales (typical damage in unconventional producing wells) in shorter soaking periods. This novel formulation cleans spontaneously by diffusion, breaking and solubilizing the organic deposits and providing the following additional benefits: Remove filter cake and formation damage created by OBM drilling and well communication.Reverse wettability of remaining particles (Water-wets) solids particles, preventing the re-agglomeration for further damage.Improve formation oil mobility by reducing the capillary pressure in the formation and maximizing productivity of the well. The work in this paper studies the effect of this novel chemistry when it is used in acid jobs, and presents case history information on testing, application, and subsequent field results across the Permian Basin unconventional production. Case history results from field trial is presented in this paper, demonstrating the advantages of utilizing this novel stimulation multifunctional chemistry in OBM removal to restore the productivity in wells damaged by OBM filtration during well communication.