Enhancement of Gas Productivity Using Alcoholic Acids: Laboratory and FieldStudies

Enhancement of Gas Productivity Using Alcoholic Acids: Laboratory and Field Studies Hamoud Ali Al-Anazi; Hamoud Ali Al-Anazi Saudi Aramco Search for other works by this author on: This Site Google Scholar Msalli Awadh Al-Otaibi; Msalli Awadh Al-Otaibi ARAMCO Overseas Co. Search for other works by this author on: This Site Google Scholar Mohammad Al-Faifi; Mohammad Al-Faifi Saudi Aramco Search for other works by this author on: This Site Google Scholar Victor V. Hilab Victor V. Hilab Saudi Aramco Search for other works by this author on: This Site Google Scholar Paper presented at the SPE Annual Technical Conference and Exhibition, San Antonio, Texas, USA, September 2006. Paper Number: SPE-102383-MS https://doi.org/10.2118/102383-MS Published: September 24 2006 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Get Permissions Search Site Citation Al-Anazi, Hamoud Ali, Al-Otaibi, Msalli Awadh, Al-Faifi, Mohammad, and Victor V. Hilab. "Enhancement of Gas Productivity Using Alcoholic Acids: Laboratory and Field Studies." Paper presented at the SPE Annual Technical Conference and Exhibition, San Antonio, Texas, USA, September 2006. doi: https://doi.org/10.2118/102383-MS Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex Search Dropdown Menu nav search search input Search input auto suggest search filter All ContentAll ProceedingsSociety of Petroleum Engineers (SPE)SPE Annual Technical Conference and Exhibition Search Advanced Search AbstractThe objectives of this study were to: investigate effectiveness of alcoholic acids to stimulate Devonian sandstone gas reservoirs, determine the optimum acid formulation, and recommend the best practices to enhance stimulation treatments in gas wells. In this study, extensive coreflood experiments were conducted on sandstone cores recovered from gas reservoirs to assess the effectiveness of various acid formulations (HCl, HCOOH, HCl/HF, and HCOOH/HF, with and without alcohols) in enhancing gas relative permeability. Several solvents and chemical additives were evaluated to remove or reduce trapped liquids.Experimental results showed commonly used completion fluids caused a severe reduction in gas relative permeability. This study indicated that alcohols can be mixed with stimulation fluid to expedite the cleanup of spent acid and help to attain maximum gas well potential directly after stimulation treatment. Experimental results showed that alcoholic acids have a slower reaction rate with rocks compared to conventional acids having the same acidity. Alcoholic acids can be injected deeper into the formation and their corrosivity can be reduced in hot deep wells with a proper use of corrosion inhibitor type and concentration. Because of low IFT of alcoholic acids, they can be easily injected into tight formation when there are limitations in injection pressure and resulted in deeper stimulation than with conventional acids. This paper discusses a case study on damage diagnosis for a gas well which was recently completed and showed unexpected low productivity. This study proposed an effective stimulation formulation for gas wells and better practices for stimulation design to reduce flowback time needed to lift spent acid and help to achieve maximum production.IntroductionStimulation of sandstone reservoirs is a challenge due to many variables contributed into acidizing efficiency, including the following acid properties: type, concentration, volume, stages, soaking time, and injection rate; in addition to variables such as, reservoir temperature, fluids, and heterogeneity, clay type and content, and damage type and depth.1–3 Gas wells in tight reservoirs have shown low gas deliverability after drilling, completion, or stimulation operations. This is partially attributed to penetration of fluids used in these operations into the formation. The invaded fluids are trapped in the formation and form a ring around the wellbore, as a result, this high liquid saturation restricts or blocks the flow of gas. The increase in liquid saturation in the vicinity of the wellbore can play a significant role in the blocking of tight rock due to high capillary forces.High liquid saturation remains around the wellbore after a stimulation or workover treatment reduces the gas relative permeability. This effect is getting more severe in the presence of condensate banking when the bottom hole flowing pressure is below the dewpoint pressure.4 A water block may occur when capillary forces exceed formation gas driving forces (drawdown pressure).5In gas wells, the cleanup of aqueous fluids was observed to take longer time due to the entrapment of injected fluids in the near wellbore region and reduce gas relative permeability. During the flow of gas, water was slowly produced. The recovery of these fluids is controlled by its capillary forces and vapor pressure. For example, some wells required a period up to a year to restore the initial gas productivity following liquid injection into the formation. Water blocking difficulty increases in low permeability formations where the capillary forces are high or in reservoirs that have low pressure.5–7 Keywords: downhole intervention, Well Intervention, enhanced recovery, drilling fluid property, drilling fluid selection and formulation, drilling fluids and materials, drilling fluid chemistry, drilling fluid formulation, Upstream Oil & Gas, precipitation Subjects: Drilling Fluids and Materials, Reservoir Fluid Dynamics, Improved and Enhanced Recovery, Formation Evaluation & Management, Drilling fluid selection and formulation (chemistry, properties), Acidizing, Flow in porous media, Well Intervention, Well Operations, Optimization and Stimulation This content is only available via PDF. 2006. Society of Petroleum Engineers You can access this article if you purchase or spend a download.