The Impact of Reservoir Fluid Compositional Variation and Valid Sample Acquisition on Flow Assurance Evaluation (2009)

The Impact of Reservoir Fluid Compositional Variation and Valid Sample Acquisition on Flow Assurance Evaluation SS-FA Oliver C. Mullins; Oliver C. Mullins Schlumberger Search for other works by this author on: This Site Google Scholar Hani Elshahawi; Hani Elshahawi Shell Search for other works by this author on: This Site Google Scholar Matthew Flannery; Matthew Flannery Shell Search for other works by this author on: This Site Google Scholar Michael okeefe; Michael okeefe Schlumberger Search for other works by this author on: This Site Google Scholar Stephane Vannuffelen Stephane Vannuffelen Schlumberger Search for other works by this author on: This Site Google Scholar Paper presented at the Offshore Technology Conference, Houston, Texas, May 2009. Paper Number: OTC-20204-MS https://doi.org/10.4043/20204-MS Published: May 04 2009 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Get Permissions Search Site Citation Mullins, Oliver C., Elshahawi, Hani, Flannery, Matthew, okeefe, Michael, and Stephane Vannuffelen. "The Impact of Reservoir Fluid Compositional Variation and Valid Sample Acquisition on Flow Assurance Evaluation SS-FA." Paper presented at the Offshore Technology Conference, Houston, Texas, May 2009. doi: https://doi.org/10.4043/20204-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 ProceedingsOffshore Technology ConferenceOTC Offshore Technology Conference Search Advanced Search AbstractThe evaluation of flow assurance concerns for oilfield development necessitates corresponding careful laboratory measurements. However, there are two issues of great concern, which are often underemphasized. First, reservoir fluids are spatially variable, both vertically and laterally, and thus tend to be temporally variable during production.For flow assurance evaluation, it is critical to understand any laboratory fluid evaluation within the context of the spatial distribution of complex fluids within the reservoir. For example, asphaltene plugging can be caused by depressurization, commingling, compositional gradients, separator gas injection, 'tar' mat mobilization and water injection issues. It is required to diagnose the problem prior to treating it. Second, it is of paramount importance that downhole sample acquisition be performed in a way to acquire valid and representative samples. Here, we discuss the latest understanding of the origins of reservoir fluid variations and the corresponding impact on flow assurance concerns. Downhole fluid analysis (DFA) is shown to be critically important for elucidating these reservoir fluid variations. The importance of disequilibrium of reservoir fluids is emphasized which dictates that proper analysis must be data-driven, not simply modeled. In addition, we discuss state-of-the-art methods to acquire valid samples. Again, DFA is the method of choice for achieving sampling objectives. In addition, the protocol for optimal selection of sample acquisition points is discussed.IntroductionHydrocarbon and even aqueous reservoir fluids can undergo a large variety of phase transitions that can be deleterious for the production of oil and gas. Figure 1 shows various solids that can form upon change of pressure, temperature or composition individually or in combination.Compositional changes can occur as a result of commingling of fluids from (miscible) flood, commingling of fluids from different reservoirs or even commingling of non-equilibrated fluids within a single reservoir. Some of these substances and their phase transitions are not well understood and are the subject of current research. For example, the molecular nature of asphaltenes is only now being elucidated [1] and their phase transitions are an active area of investigation.[1] For a given oilfield, it is essential to acquire representative samples of the reservoir fluids to evaluate if any flow assurance issues are of concern. Openhole wireline formation sampling tools (WFTs) are routinely used for this purpose; Figure 2 shows a schematic of a typical tool string used to acquire formation samples in openhole.[2] Also shown in Fig. 2 is a picture of the probe module which is the all important interface of the formation with the WFT tool. Within this setting, it is essential to minimize contamination of miscible mud filtrate. In particular, contamination of live crude oil samples with filtrate of oil based muds (OBM) is of prime concern. Moreover, it is imperative to avoid phase transitions during sample acquisition, otherwise the differential flow of the different phases all but guarantees invalid sample acquisition. Keywords: equation of state, evaluation, fluid modeling, methane, drilling fluids and materials, gradient, assurance, drilling fluid selection and formulation, well logging, upstream oil & gas Subjects: Drilling Fluids and Materials, Fluid Characterization, Formation Evaluation & Management, Drilling fluid selection and formulation (chemistry, properties), Fluid modeling, equations of state, Open hole/cased hole log analysis, Formation test analysis (e.g., wireline, LWD) This content is only available via PDF. 2009. Offshore Technology Conference You can access this article if you purchase or spend a download.