Article Review: Horizontal WellAcidizing
The current article was preparedfor presentation by the Society of Petroleum Engineers (SPE)Committee at their annual technical conference and exhibition thatwas held in Florence Italy. The article is about the comprehensivemodel of high-rate matrix acid stimulation for long horizontal wellsin carbonate reservoirs and the authors were all members of the SPE.The paper notes that the matrix acidizing models have over timeunder-predicted the acid simulation benefits because ofunder-prediction of the wormhole penetration and resulting completionskin factors for the vertical wells. Therefore, the paper presentsresults of a matrix acid simulation model for typical horizontal welland presents a practical tool in engineering that can necessitatematric acid simulation in carbonate wells. The results of this paperare critical in removing the uncertainty that surrounds the currenttheoretical models and the associated design procedures in acidsimulation of horizontal wells in carbonate reservoirs.
The paper develops an integratedflow model to predict wormhole distribution and wellbore pressureprofile. The wormhole growth model developed was based on theempirical correlation by Buijse and Glasberg (2005). In application,the wormhole model shows the wormholing of the acid through thecarbonate formation which is believed to provide significantsimulation. The post-simulation skins obtained were from -3.5 to -4.0compared to the previously predicted values that ranged from -1.0 to-2.0. On the other hand, the wellbore model developed is capable ofpredicting the wellbore pressure profile and distribution length.
The paper follows the structureof a report, with abstract presenting the summary of the paper, theintroduction and results of the study, hence easy to understand thelogic of the paper. I feel that the authors have succeeded inbringing out the content of the paper by ensuring that the grammar issimple to understand and terms used are well defined in nomenclaturesection. This makes it easier even for non-technical persons tounderstand the paper. The reliability of the paper is wellillustrated from the rich use of information from other sourcesrelated to the topic as presented in the reference section. Theauthors extensively used equations, graphs and figures to illustratethe results. This enhances the understanding of the paper. Thelength of the article is typical of the presentation and white paperswhich is not very long.
Reference papers that have beenused to supplement the current paper include SPE production andOperation Paper on holistic fracture diagnosis, Analysis of sphericalflow with wellbore storage, understanding wormholing mechanisms thatcan improve acid treatment in carbonate formations, semi-empiricalmodel to calculate wormhole growth in carbonate acidizing and effectsof perforation-entry on bottom-hole treating analysis.
In conclusion, the authors havelogically presented a model that demonstrates that acid warmholingthrough the carbonate formations can be used to provide in simulationfor the post simulation skins of the -3.5 to -4.0 range, and hasshown that post-job evaluations is critical in evaluatingeffectiveness of acid treatments. Despite the technical nature of thepaper, the authors have explicitly defined all the terms and thepaper is thus easily understandable. This research work is thereforenot only relevant to SPE fraternity but also critical for furtheringknowledge in horizontal well acidizing.
Furui, K., Burton, R., Burkhead, D. W., & Addelmalek, N. (2010). A comprehensive Model of High-Rate Matrix Acid Stimulation for Long Horizontal Wells in Carbonate Reservoirs. SPE Annual Technical Conference and Exhibition (pp. 1-28). Florence, Italy: Society of Petroleum Engineers.