Case Study of Permeability, Vug Quantification, and Rock Typing in a ComplexCarbonate (2006)

Case Study of Permeability, Vug Quantification, and Rock Typing in a Complex Carbonate Nasser Mahmoud Gomaa; Nasser Mahmoud Gomaa Abu Dhabi Marine Operating Co. Search for other works by this author on: This Site Google Scholar Samir Raphael Azer; Samir Raphael Azer Abu Dhabi Marine Operating Co. Search for other works by this author on: This Site Google Scholar Djamel Eddine Ouzzane; Djamel Eddine Ouzzane Abu Dhabi Marine Operating Co. Search for other works by this author on: This Site Google Scholar Omar Saif; Omar Saif ADMA OPCO Search for other works by this author on: This Site Google Scholar Moyosore O. Okuyiga; Moyosore O. Okuyiga Abu Dhabi Marine Operating Co. Search for other works by this author on: This Site Google Scholar David Furse Allen; David Furse Allen Schlumberger Search for other works by this author on: This Site Google Scholar David Rose; David Rose Schlumberger Search for other works by this author on: This Site Google Scholar Raghu Ramamoorthy; Raghu Ramamoorthy Schlumberger Search for other works by this author on: This Site Google Scholar Emmanuel Bize Emmanuel Bize Schlumberger 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-102888-MS https://doi.org/10.2118/102888-MS Published: September 24 2006 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Get Permissions Search Site Citation Gomaa, Nasser Mahmoud, Azer, Samir Raphael, Ouzzane, Djamel Eddine, Saif, Omar, Okuyiga, Moyosore O., Allen, David Furse, Rose, David, Ramamoorthy, Raghu, and Emmanuel Bize. "Case Study of Permeability, Vug Quantification, and Rock Typing in a Complex Carbonate." Paper presented at the SPE Annual Technical Conference and Exhibition, San Antonio, Texas, USA, September 2006. doi: https://doi.org/10.2118/102888-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 AbstractThis case study demonstrates a new method to compute continuous permeability and estimate reservoir rock type from logs in a complex, heterogeneous, Middle Eastern carbonate reservoir. The 795 ft conventionally cored interval consists of interbedded limestones and dolomites with anhydrite cement and features a wide variety of textures. In some intervals the depositional textures are preserved, in others they are highly altered by diagenesis. Vugs are developed in several intervals. Computation of permeability from porosity alone yields scatter of a factor of 700. Rock typing using only conventional logs was unsatisfactory due to the poor permeability estimation.The effect of geological complexity on the log based prediction is overcome by including pore size distribution data from a combination of NMR and borehole electrical image logs. This data is sufficient to partition the porosity according the pore size, compute permeability and assess the rock types, independently of mineralogy, facies, and other variables. The results are validated by comparison to core derived properties and formation tester mobilities. Incorporation of the pore size information into the log based interpretation reduces the scatter in computed permeability to a factor of less than 10.The assumptions and principles of the log analysis method were validated in the lab through extensive characterization of the pore system over a range of scales. Data from a variety of methods including MICP, lab NMR, BET surface area, thin section analysis, continuous vuggy porosity analysis from the core slab, minpermeametry and other advanced research methods are included.A key result of this study is that a relatively simple method for log derived permeability and rock type analysis in carbonates, first developed in high porosity limestones, can be successfully applied in this lower porosity (10 - 20 p.u.) carbonate. This gives us confidence to project that the method could be applicable to many other carbonates worldwide.IntroductionThe well in this case study is from a Middle East carbonate reservoir consisting of interbedded limestones and dolomites with anhydrite cement. Seven hundred ninety-five feet of core was recovered. A wide variety of carbonate textures is present. In some intervals, depositional textures ranging from grainstones to mudstones, are preserved. In other intervals, the depositional texture is highly altered by diagenesis. This is illustrated in Fig. 1 which shows the results of core mineralogy analysis, core based Dunham classification and high resolution sequence stratigraphy.The high resolution sequence stratigraphy, which recognized multiple transgressive system tracts and high stands, was based upon recognition of grain size trends, bioturbation, and surfaces in the core. The transgressive system tracts are characterized by highly burrowed packstones, and/or wackestones (typical burrower is thalassinoides) capped by a dense bored or burrowed surface. By contrast, the high stands are dominated by high energy deposits (grainstone layers, cross bedding, etc.), rich in macrofossils. Vugs are developed in some intervals. The other common texture is that of sucrosic dolomite, of varying crystal size.Due to this geologic complexity, the quantification of permeability, and by extension rock typing from traditional logs and interpretation methods does not yield satisfactory results (Fig. 2). One of the primary objectives in this case study was to identify logging technologies and interpretation methods that would improve the prediction of permeability, quantify the vuggy porosity and provide reliable rock typing. The main benefits of validating a successful log based model would be an improved geological and simulation model that could be applied to future uncored wells. Keywords: well logging, variation, cutoff, porosity, Upstream Oil & Gas, vug quantification, log analysis, vuggy porosity, NMR, electrical image Subjects: Formation Evaluation & Management, Open hole/cased hole log analysis This content is only available via PDF. 2006. 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