One-Step Acid Removal of an Invert Emulsion (2005)

One Step Acid Removal of Invert Emulsion Lirio Quintero; Lirio Quintero Baker Hughes INTEQ Search for other works by this author on: This Site Google Scholar Tom A. Jones; Tom A. Jones Baker Hughes INTEQ Search for other works by this author on: This Site Google Scholar David Erle Clark David Erle Clark Baker Hughes Drilling Fluids Search for other works by this author on: This Site Google Scholar Paper presented at the SPE European Formation Damage Conference, Sheveningen, The Netherlands, May 2005. Paper Number: SPE-94604-MS https://doi.org/10.2118/94604-MS Published: May 25 2005 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Get Permissions Search Site Citation Quintero, Lirio, Jones, Tom A., and David Erle Clark. "One Step Acid Removal of Invert Emulsion." Paper presented at the SPE European Formation Damage Conference, Sheveningen, The Netherlands, May 2005. doi: https://doi.org/10.2118/94604-MS Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll ProceedingsSociety of Petroleum Engineers (SPE)SPE European Formation Damage Conference and Exhibition Search Advanced Search AbstractRemoval of skin damage resulting from internal and external filter cake deposition during oil well reservoir drilling with invert emulsion drill-in fluid is desirable in order to maximize hydrocarbon recovery.Efficient filter cake cleanup is required for a number of open-hole completion operations, including the use of stand-alone and expandable sand screens, and conventional gravel pack applications for both production and water-injection wells.Most of the currently used chemical methods to remove invert emulsion filter cake and internal formation damage are based on the use of acids, solvents and mutual solvents mixed in clear brine. Completing a well after drill-in with emulsion-based fluids is time-consuming and costly, and usually involves large volume multi-stage soak treatments.Surfactant technology, when appropriately combined with conventional acid, allows a single-stage invert emulsion cleanup process. In this "one-step" cleanup method, the invert emulsion filter cake is incorporated into the organized surfactant in solution and the acid-soluble particles are then decomposed.A number of injection permeability tests were performed on Berea sandstone cores and ceramic discs using various invert emulsion drilling fluids for filter cake deposition and organized surfactant in solution/acid blends for filter cake removal. This investigation demonstrated that, when using this technology to destroy the filter cake, (1) the invert emulsion is incorporated into the surfactant solution, (2) the solids become water-wet, (3) sludge formation between the acid and invert emulsion cake is prevented, and (4); and the majority of acid-soluble particles are removed.This approach appears to be a credible method for removing formation skin damage and increasing hydrocarbon recovery and/or water injection rates.IntroductionMany operators are interested in improving filter cake cleanup after drilling into reservoirs with invert emulsion drilling fluids.More efficient filter cake cleanup is desired for a number of open hole completions, including stand-alone and expandable sand screens, as well as for gravel pack applications for both production and water injection wells.One-step invert emulsion filter cake cleanup technology uses a single-phase microemulsion (SPME)[1–3] and conventional acid packages, in a single blend, to solubilize the oil into the SPME, reverse the wettability of the filter cake solids, and simultaneously decompose its acid-soluble components.Reversing the wettability of the filter cake, using surface active chemistry, facilitates acidizing by preventing a sludge that could form between the acid and the emulsified cake and by making acid-soluble particles unavailable to unspent acid.Besides the advantage of reduced skin damage, increased hydrocarbon recovery and/or increased water injection rates, a "one-step" near wellbore cleanup method will save an operator valuable rig time.Theory of MicroemulsionIn the 1950s, Schulman and co-workers added alcohol to surfactant-stabilized oil-in-water (o/w) emulsions to obtain very stable homogeneous fluids that he called microemulsions.[4] These microemulsions had an average droplet size of 10–100 nanometers (nm), much smaller than conventional emulsions.The first studies of microemulsions in the oil industry were in the 1970's for enhanced oil recovery (EOR) applications.[5–11] Many oil operators and universities invested considerable time to research this topic. The research group led by Schechter and Wade at The University of Texas at Austin made important contributions to the understanding of the mechanism of increased production by microemulsions. However, the interest dropped due to the crude oil price decrease and because the technology was expensive, due mainly to the high concentration of surfactant required. Since then, the oil industry has conducted only a small amount of research on microemulsions. Keywords: upstream oil & gas, invert emulsion, enhanced recovery, surfactant, cacl 2, acid, microemulsion, soak solution, drilling fluids and materials, permeameter Subjects: Drilling Fluids and Materials, Improved and Enhanced Recovery, Drilling fluid selection and formulation (chemistry, properties) This content is only available via PDF. 2005. Society of Petroleum Engineers You can access this article if you purchase or spend a download.