Obtaining Formation Water Chemistry Using a Mud Tracer and Formation Tester in a North Sea Subsea Field Development (2004)

Obtaining Formation Water Chemistry Using a Mud Tracer and Formation Tester in a North Sea Subsea Field Development M.H. Hodder; M.H. Hodder M-I SWACO Search for other works by this author on: This Site Google Scholar Samir Magdy; Samir Magdy Schlumberger Search for other works by this author on: This Site Google Scholar G. Holm; G. Holm Total Search for other works by this author on: This Site Google Scholar G. Segret G. Segret Total Search for other works by this author on: This Site Google Scholar Paper presented at the SPE Asia Pacific Oil and Gas Conference and Exhibition, Perth, Australia, October 2004. Paper Number: SPE-88637-MS https://doi.org/10.2118/88637-MS Published: October 18 2004 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Get Permissions Search Site Citation Hodder, M.H., Magdy, Samir, Holm, G., and G. Segret. "Obtaining Formation Water Chemistry Using a Mud Tracer and Formation Tester in a North Sea Subsea Field Development." Paper presented at the SPE Asia Pacific Oil and Gas Conference and Exhibition, Perth, Australia, October 2004. doi: https://doi.org/10.2118/88637-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 Asia Pacific Oil and Gas Conference and Exhibition Search Advanced Search AbstractPrecipitation from and corrosion by formation water co-produced with target hydrocarbons can cause serious problems, and an early knowledge of water chemistry is important for completion and facilities design. Owing to the high cost of interventions, this knowledge is particularly important in deepwater developments and subsea completions.Samples of formation water are obtained by producing from the well completed in the water leg or sampling after water production occurs naturally. The former method carries significant cost and the latter method may delay the knowledge of the water chemistry.Alternatively, a formation tester can be run into the wellbore to collect small samples directly from the formation.. In wells drilled with water-based mud, the results are generally mixed because successful collection of formation water requires that the tool be able to discriminate between the water and invaded filtrate. The method depends on the contrast in color or resistivity between formation water and water-based mud filtrate to determine when it is collecting water, and this contrast often doesn't exist.This paper presents a new solution. A mud tracer was used to change the optical properties of the mud filtrate to make it detectable downhole. Laboratory experiments checked the compatibility of the tracer with gypsum or glycol mud system, sensitivity to high clay content, and ability to be detected with another tracer, and individually and in combination with a dark-colored filtrate. Shop experiments were carried out to establish a relationship between different tracer concentrations and optical properties at specific wavelengths. This relationship represents the basis of tracer detection and contamination prediction in real time downhole.The first trial was carried in the Otter field in the northern North Sea. The field comprises three producers and two injectors with subsea completions. Downhole water samples were obtained during the logging phase on one of the injectors at an early stage of the field development. Sample quality and flushing time were optimized using the new technique. Sample analysis results compared well with later production tests.IntroductionWater production happens naturally in many oilfields. Generally, the production of water is unwanted and measures are taken to avoid or to minimize it. Knowledge of the chemistry of the produced water is incorporated into the production process. For example, potential for scaling and corrosion influences material selection of the well completions and surface facilities. The quality of produced water may also impact the decision about water injection for the fear of mixing incompatible waters.1It is expensive to dedicate a production test for the sole purpose of obtaining a formation water sample. Although information about water chemistry is important, the cost of obtaining a sample can be high enough that the test may be delayed or canceled if obstacles arise. Wells generally are completed with the aim of preventing or at least delaying water production, so it sometimes seems easy to defer analysis. Water chemistry may thus be only available when water production naturally occurs, long after metal completion goods, chemical injectors, etc. have been placed. This may not be the ideal situation.Therefore, obtaining a formation water sample using a wireline formation tester at an early stage of field development is an attractive solution. If the sampled well is drilled with oil-based mud (OBM), current technology provides a simple way to differentiate between OBM filtrate and formation water2,3. If the sampled well is drilled with water-based mud (WBM), differentiation can be difficult. The most commonly used downhole sensors rely on resistivity or the colour difference between formation water and WBM filtrate. Often these values are close and can not be used as a mean of differentiating the two fluids. As we report, adding the proper synthetic dye to the WBM colors the filtrate, providing clear differentiation from formation water. Keywords: channel 1, dye concentration, upstream oil & gas, drilling fluid property, wireline formation tester, spe 88637, formation water, drilling fluid selection and formulation, filtrate, contamination Subjects: Drilling Fluids and Materials, Formation Evaluation & Management, Drilling fluid selection and formulation (chemistry, properties) This content is only available via PDF. 2004. Society of Petroleum Engineers You can access this article if you purchase or spend a download.