Schlumberger

Technical Paper: Hydrocarbon compositional analysis in-situ in openhole wireline logging

Society: SPWLA
Paper Number: 2004fff
Presentation Date: 2004
 

Abstract

In the development of deepwater and other expensive prospects, it is essential to understand the precise nature of the hydrocarbon fluids in terms of chemical and physical properties, all phase transitions, and commingling incompatibilities. Hydrocarbon sample acquisition and analysis, if performed improperly, can yield invalid results leading to costly corrective measures. The best assurance for accuracy is to perform hydrocarbon analysis at the point of sample acquisition during openhole wireline logging — this agenda is now embodied in Downhole Fluid Analysis (DFA). In particular, understanding compartmentalization, fluid compositional grading and flow assurance requires DFA in order to improve efficiencies. Testing the dynamic response of the fluids during the sample acquisition process provides confirmation of hydrocarbon fluid type and character as well as insight into formation characteristics. Here, we describe new methods of in-situ hydrocarbon compositional analysis or DFA by near-infrared spectroscopy (NIR). Using this method, sample analysis and acquisition can be independently optimized thereby allowing improved operational performance. In addition, we describe how two fluid analyzers at different locations in the sampling tool string coupled with (effective) tool-separator volumes can be used to ascertain detailed fluid properties.

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