Cointerpretation of Distributed Acoustic and Temperature Sensing for Improved Smart Well Inflow Profiling

Abstract

Abstract Current advances in the well completion technology have allowed for more complex smart well instrumentations with marginal additional cost. As an example, optical fibers can be run along horizontal wells to provide acoustic and temperature data that are distributed both in time and space. With such data at our disposal, an immediate evaluation of the well response is possible as changes in the reservoir or well occur. Most current work in distributed measurements looks at Distributed Acoustic Sensing (DAS) or Distributed Temperature Sensing (DTS) data individually, which limits our inferences about the multiphase flow problem. The objective of this work was to look at the two pieces of data together and determine what improvements can be achieved in multiphase flow problems compared to the conventional methods of looking at each DAS and DTS alone. The study began by evaluating the performance of DAS in analyzing two-phase flow; a process which begins by extracting the speed of sound within the fluid medium from the acoustic signal, then obtaining the phase fraction combination that obtains this speed of sound reading. Another procedure is explained to obtain similar results from DTS measurements. In this case, however, the in-situ phase fractions are correlated to the Joule-Thomson effect as reservoir fluids enters the wellbore. As both these procedures are limited to one- and two-phase flow applications, we extended the solution to work in three-phase flow problems by combining information from DAS and DTS. The flow profiling procedure was applied to two smart wells in the Middle East. Flowrates from different segments of the well were calculated and results were in close agreement with a surface flowmeter for most sections of the well. In cases where both DAS and DTS were not available for the same well, a commercial compositional and thermal reservoir simulator was used to generate synthetic examples. By applying the developed procedure, we found that cointerpretation of DAS and DTS data yields accurate in-situ three-phase fractions for all ranges of water cuts and gas volume fraction. In comparison, analyzing DAS or DTS individually is usually not sufficient to fully determine a three-phase flow problem.