Rosanel Morales, Revive Energy Solutions
Fadi El Ahmadieh and Max Reynolds, ConocoPhillips
Gradual diminution of the flow path of hydrocarbon in the near-wellbore area is heavily linked to formation damage accumulation and well productivity reduction. Organic deposition in the formation and well bore area can result from the use of hydrochloric acid (HCl) during acidizing, especially in the presence of free iron, addition of organic liquids such as diesel, kerosene, or gasoline and the use of CO2 injection for EOR projects. Laboratory evaluation of the nature of the crude oil and stimulation fluids indicates the potential severity of the problem.
The usage of organic and inorganic acids for inorganic deposits removal like calcium carbonate and iron sulfide has become one of the most used methods for well clean-up and stimulation. Unfortunately, due to the nature of the produced fluids, organic deposits like paraffin are coating 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 cannot be fully miscible in the volume of the acid, and they only dissolve a specific weight of paraffin based upon the molecular weight of the wax, temperature, and pressure before the solvent’s power is exhausted.
A multipackage formulation has been developed, to be 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 (formation, 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
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 conventional and unconventional production.