Novel Multi-Functional Chemistry to Maximize Performance in Paraffin Coated Acid Soluble Scale Cleanups

Abstract

Abstract Gradual diminution of the flow path of hydrocarbon in the near-wellbore area is actively linked to formation damage accumulation and a reduction in well productivity. Organic deposition in the formation and wellbore area can result from the use of hydrochloric acid (HCl) during acidizing, especially in the presence of free iron and organic liquids such as diesel, kerosene, or gasoline. Laboratory evaluation of the nature of the crude oil and stimulation fluids indicates the potential severity of the problem. This test is called acid sludge test. Utilization of inorganic acid like HCl for inorganic deposits removal, like calcium carbonate and iron sulfide, has become one of the most common methods for well clean-up and stimulation. Unfortunately, due to the nature of the produced fluids (hydrocarbon), organic deposits like paraffin compounds under certain conditions, come out of solution, creating a coating on the inorganic scale, minimizing the performance of the acid job. Typical aromatic solvents utilized to address the organic deposits are not highly effective, as they are not fully miscible in the volume of the acid, and only dissolve a specific weight of paraffin before the solvent’s power is exhausted. A multipackage formulation has been developed, fully miscible in acid, maximizing the performance of the scale dissolution, by effectively de-oiling and penetrating the organic coating layer build-up on calcium carbonate and iron sulfide scales in shorter soaking periods. This novel formulation cleans spontaneously by diffusion, breaking and solubilizing the organic deposits and providing the following additional benefits: Water-wets the surfaces (near-wellbore area, downhole equipment, tubing, and flowlines), including paraffin particles, preventing the re-agglomeration further down in the system.Improves formation oil mobility by reducing the capillary pressure in the formation.Prevents emulsion creation and acid sludge formation during acid jobs as formulation is fully miscible in acid. 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, chemical application, and subsequent field results across the Permian Basin in unconventional production.