Single Well Tests To Determine the Efficiency of Alkaline-Surfactant Injection in a Highly Oil-Wet Limestone Reservoir.

Abstract

Single Well Tests to determine the Efficiency of Alkaline-Surfactant Injection in a highly Oil-Wet Limestone Reservoir Hisham K. Zubari; Hisham K. Zubari Bahrain Petroleum Company Search for other works by this author on: This Site Google Scholar V.C. Babu Sivakumar V.C. Babu Sivakumar Bahrain Petroleum Company Search for other works by this author on: This Site Google Scholar Paper presented at the Middle East Oil Show, Bahrain, June 2003. Paper Number: SPE-81464-MS https://doi.org/10.2118/81464-MS Published: June 09 2003 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Get Permissions Search Site Citation Zubari, Hisham K., and V.C. Babu Sivakumar. "Single Well Tests to determine the Efficiency of Alkaline-Surfactant Injection in a highly Oil-Wet Limestone Reservoir." Paper presented at the Middle East Oil Show, Bahrain, June 2003. doi: https://doi.org/10.2118/81464-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 Middle East Oil and Gas Show and Conference Search Advanced Search AbstractThe Mauddud carbonate reservoir is the main oil producer in Bahrain oilfield that has been undergoing crestal gas injection with natural aquifer support at the flanks. It has been producing since 1932 and currently in a very mature stage. Due to its rocks wettability characteristics (preferentially oil-wet nature), the residual oil left behind gas and water fronts range from 20–70%. One of the potential options to recover portion of this residual oil is through Chemical Flooding possibly Alkaline-Surfactant-Polymer (ASP) flood. A project was hence initiated to investigate its technical and economical feasibility. It was decided to carry out field experiments to gauge the reservoir response through well-bore treatments before proceeding with a full-scale study and field pilot implementation. Initial field-testing on single-well huff-and-puff basis with experimental recipes provides sufficient positive indications for the project to proceed.The results of these initial tests are presented in this paper.IntroductionThe subject Mauddud Reservoir has been under crestal gas injection for pressure maintenance for the past 65 years. While expanding gas cap influences the recovery from the crestal portions of the reservoir cap, the north and south flanks are influenced by water displacement from the aquifer. Being a preferentially oil wet reservoir it has been observed that very high water cuts prevail even with oil saturations as high as 70–80% in the water contacted areas. Therefore, it is necessary to produce it albeit at water cuts as high as 98–99% and high rates of about 3500 bpd. It was therefore decided to look for a wettability reversal treatment and flood scheme to recover trapped oil, which would otherwise be bypassed.Towards this end single-well Alkaline-Surfactant (AS) treatments were carried out in several wells with different Alkali/Surfactant formulations. The first phase of the experiment involved the accurate testing of the wells' produced fluids to obtain reliable water cuts following which base saturation logs (RST-C/O) was obtained. Thereafter treatments were carried out and additional saturation logs (RST-C/O) were recorded soon after the treatment. After a soaking time of about 72 hours, wells were flowed back and the water cuts were monitored until wells returned to their original performances. Prior to the treatments the wells were acidized and pressure buildup surveys were run on the subject wells in order to assess skin damage. These buildups helped eliminate any stimulation effects from the post treatment performance. Keywords: surfactant treatment, upstream oil & gas, injection, enhanced recovery, effectiveness, reservoir, surfactant, wettability alteration, bahrain field, society of petroleum engineers Subjects: Improved and Enhanced Recovery, Chemical flooding methods This content is only available via PDF. 2003. Society of Petroleum Engineers You can access this article if you purchase or spend a download.