Productivity Decline in Oil Wells Related to Asphaltene Precipitation and Emulsion Blocks (2002)

Productivity Decline in Oil Wells Related to Asphaltene Precipitation and Emulsion Blocks Sunil Kokal; Sunil Kokal Saudi Aramco Search for other works by this author on: This Site Google Scholar Naseem Dawood; Naseem Dawood Saudi Aramco Search for other works by this author on: This Site Google Scholar Jerry Fontanilla; Jerry Fontanilla Saudi Aramco Search for other works by this author on: This Site Google Scholar Abdullah Al-Ghamdi; Abdullah Al-Ghamdi Saudi Aramco Search for other works by this author on: This Site Google Scholar Hisham Nasr-El-Din; Hisham Nasr-El-Din Saudi Aramco Search for other works by this author on: This Site Google Scholar Yousef Al-Rufaie Yousef Al-Rufaie 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, September 2002. Paper Number: SPE-77767-MS https://doi.org/10.2118/77767-MS Published: September 29 2002 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Get Permissions Search Site Citation Kokal, Sunil, Dawood, Naseem, Fontanilla, Jerry, Al-Ghamdi, Abdullah, Nasr-El-Din, Hisham, and Yousef Al-Rufaie. "Productivity Decline in Oil Wells Related to Asphaltene Precipitation and Emulsion Blocks." Paper presented at the SPE Annual Technical Conference and Exhibition, San Antonio, Texas, September 2002. doi: https://doi.org/10.2118/77767-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 Annual Technical Conference and Exhibition Search Advanced Search AbstractA few oil wells in a Saudi Arabian field have shown significant oil productivity decline in recent years. A few of them have 'died' prematurely while others have become intermittent producers. It has been noticed that the oil productivity decline is aggravated with water encroachment. The oil productivity decline has come about with relatively low water rates and without any significant drop in reservoir pressure. These wells have low productivity index (PI) resulting in relatively low flowing bottom hole pressures (FBHP).This paper presents the results of an investigative case study to determine the causes of productivity decline in these wells. A multi-disciplinary team was set up with engineers and scientists from reservoir management, production engineering and the R&D Center for the investigative study. The team focused on multiple aspects including reservoir and production engineering, as well as a comprehensive laboratory and field investigation.The results of this study indicate that one of the main causes of productivity decline in these wells is related to asphaltene precipitation and the subsequent formation of tight emulsions downhole. The emulsions block the pore throats and cause formation damage leading to productivity decline. Another factor that further aggravates the productivity of these wells is poor rock quality in the area. Possible causes of formation damage due to inorganic scaling, and leakage and mixing of gas from a deeper reservoir have been eliminated.Well test analyses on some of the affected wells shows the formation damage mechanism in the affected area is further aggravated by poor reservoir rock quality. The time-lapse pressure transient analysis also indicates a deterioration of skin and productivity with time.Based on these findings a special solvent treatment was recommended and designed as a pilot trial for one of the dead wells. The treatment included squeezing xylene and demulsifier to dissolve the asphaltenes and break the tight emulsions around the wellbore area. The treatment resulted in only a slight improvement in the productivity index and the well died after a few days. Currently a stimulation treatment with acid and demulsifier is being implemented in selected wells. The results of the field trials will be described in the paper.IntroductionSeveral wells in the northwestern part of a Saudi Arabian field have shown productivity decline in recent years. A few of them have died prematurely at relatively low watercuts, some as low as 25%, which is atypical behavior for wells in the area. It has been noticed that the oil productivity decline is aggravated when wells become wet. The oil productivity decline has come about with water rates remaining mostly stable and without any significant drop in reservoir pressure. A location map of affected wells is shown in Figure 1.Oil and water production rates are plotted in Figures 2–4 for three affected wells. The oil production rates declined from ~10–12,000 BPD to less than 1,000 BPD over a period of approximately 4–5 years. Water rates remain generally low at less than 2000 MBD. It can also be observed that the oil rate decline is substantial as soon as water breaks through in the well.This study was initiated with the objective of finding the causes of productivity decline in these wells and finding effective ways to mitigate the problem. A multi-disciplinary team was set up with members from reservoir and production engineering and the R&D Center. Several potential causes of productivity decline in these wells were investigated including the precipitation of asphaltenes, emulsion blocking, mixing of hydrocarbons from a deeper reservoir, inorganic scale precipitation, aquifer brine and injected water compatibility, regional geology including rock quality, drilling fluid damage, and distance of wells from the Gas Oil Separation Plant (GOSP). Keywords: formation damage, laser power, tight emulsion, emulsion, production chemistry, scale inhibition, depressurization, composition, asphaltene inhibition, reservoir Subjects: Production Chemistry, Metallurgy and Biology, Inhibition and remediation of hydrates, scale, paraffin / wax and asphaltene This content is only available via PDF. 2002. Society of Petroleum Engineers You can access this article if you purchase or spend a download.