The Missing Link--Identification of Reservoir Compartmentalization Through Downhole Fluid Analysis (2005)

The Missing Link-Identification of Reservoir Compartmentalization Through Downhole Fluid Analysis Hani Elshahawi; Hani Elshahawi Shell Intl. E&P Inc. Search for other works by this author on: This Site Google Scholar Mohamed Naguib Hashem; Mohamed Naguib Hashem Shell Intl. E&P Inc. Search for other works by this author on: This Site Google Scholar Oliver C. Mullins; Oliver C. Mullins Schlumberger Oilfield Services Search for other works by this author on: This Site Google Scholar Go Fujisawa Go Fujisawa Schlumberger Oilfield Services Search for other works by this author on: This Site Google Scholar Paper presented at the SPE Annual Technical Conference and Exhibition, Dallas, Texas, October 2005. Paper Number: SPE-94709-MS https://doi.org/10.2118/94709-MS Published: October 09 2005 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Get Permissions Search Site Citation Elshahawi, Hani, Hashem, Mohamed Naguib, Mullins, Oliver C., and Go Fujisawa. "The Missing Link-Identification of Reservoir Compartmentalization Through Downhole Fluid Analysis." Paper presented at the SPE Annual Technical Conference and Exhibition, Dallas, Texas, October 2005. doi: https://doi.org/10.2118/94709-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 AbstractReservoir compartmentalization is a major cause of production underperformance in the oilfield. A well drilled into a compartmentalized reservoir will see only part of the hydrocarbon in place over the production time scale. The obstruction to free flow can be sealing faults, fault baffles, pinching out layers, sand lenses or low permeability areas. Although it is recognized that a comprehensive approach to compartmentalization must make combined use of all available rock and fluid data, the case studies in this paper show Downhole Fluid Analysis (DFA) to be one of the most effective techniques in recognizing compartmentalization via fluid signature comparisons and fluid density inversions. Corroboration with geological, petrophysical, reservoir engineering and production data confirms the strength of the DFA technique.Fluid compositional variations must be considered in order to acquire fluid samples representative of the reservoir at large and to devise optimal production strategies. In addition, fluid compositional variations can be utilized as a tool to identify compartmentalization because different compartments are likely to be filled with different fluids. The limitation on use of such techniques in the past has been the need to rationalize the use of wireline sampling to collect and analyze only the necessary samples. In this paper, DFA is shown to be the "missing link." It provides the information necessary to optimize the sampling process and to decide in real time on where sampling is needed without necessarily having to bring all samples to surface.IntroductionReservoir heterogeneity at a variety of scales can be caused by structural complexity, stratigraphic stacking patterns, or diagenetic alteration of pore system continuity. This heterogeneity commonly causes barriers or baffles to fluid flow. Such heterogeneity, often manifested as compartments at the reservoir scale, tends to hinder. The consequence of not recognizing flow compartmentalization is generally to anticipate more efficient drainage than is actually achieved. As a result, facilities are improperly sized, and reserves, production, and cash flow models suffer from inaccuracies.Various techniques exist to assist operators in detecting compartmentalization. In deep water and similar high cost operating environments, the traditional methods, drill stem tests (DST) and extended well tests (EWT) often become impractical, with costs approaching the costs of new wells and with emissions becoming increasingly undesirable. Thus, compartments often have to be identified by some other means. Looking for pressure continuity is one widely used method, but it is important to keeping mind that pressure communication is a necessary yet insufficient criterion to establish fluid communication particularly in normally-pressured basins. In other words, reservoirs in pressure equilibrium are not necessarily in thermodynamic equilibrium and/or flow communication, and being able to fit a single linear pressure gradient to a number of small compartments does not necessarily mean that they are in flow communication. One can easily imagine two large sand bodies with an intervening shale layer. If the shale layer has a few baffles or leaky faults connecting the sands, there will be pressure communication over geologic time, but little or no flow communication.Geochemical and other surface analytical methods can be applied to hydrocarbon fluid samples to help uncover compartmentalization. The problem is that without a priori knowledge that fluid complexities exist, the cost of comprehensive multiple sample acquisition is prohibitive. In addition, due to frequent discrepancies involved in sample acquisition, transfer and lab analysis, redundant samples are routinely processed further adding to the cost. What is needed is a new, cost effective technology to reveal fluid complexities, one for which costs are commensurate with the value of the information. Keywords: gradient, variation, composition, mullin, drillstem testing, log corresponding, downhole fluid analysis, drillstem/well testing, fingerprint, dfa station Subjects: Reservoir Characterization, Formation Evaluation & Management, Drillstem/well testing This content is only available via PDF. 2005. Society of Petroleum Engineers You can access this article if you purchase or spend a download.