New Production Logging Tool for Inflow Profiling of Low-Rate Oil and Water Horizontal Wells: Case Studies of Field Testing an Experimental Prototype

Abstract

Abstract The current results of development of a new production logging (PL) tool based on an azimuthally distributed array of thermal anemometers and aimed at determination of inflow profiles beyond the limits of common mechanical sensors in horizontal wells producing oil and water at low rates are described in this paper. Theoretical background, implementation technique, and experimental prototype (EXP) were developed for the PL tool using azimuthally distributed thermo-anemometer (TA) sensors to obtain a dataset characterizing the production regime in low-rate (below 150 m3/d) oil and water horizontal wells. The new PL tool's TA sensors record overheating profiles along a well that depend on the local velocity of the fluid and its phase composition. The periodic heating regime of the TA sensors enabled measuring the undisturbed fluid temperature for determination of overheating and acquiring high-resolution temperature profiles, thus providing a valuable additional dataset of diagnostic attributes for characterization of the inflow. Laboratory testing allowed determination of calibration dependencies of TA signals versus velocities of single-phase water and oil flows. The calibrations were used for interpretation of data obtained with the PL tool and evaluation of the distribution of fluid phases for cross sections along a well and profiles of phase velocities. These results indicated the new tool's potential for implementation with a standard PL toolstring in low-rate oil and water horizontal wells. Interpretation of the EXP data together with that from standard PL tools enhanced the reliability of the determination of inflow zone intervals, phase composition of an inflowing fluid, and phase distribution of producing fluid along a well. Analysis of the field data established that effective resolution of temperature measurements by the new PL tool is approximately 0.015 K to enable registration of the effective fluid velocity in range of 0.5 to 15 m/min with corresponding resolution of 0.01 to 0.3 m/min to result in a spatial resolution of 1 to 20 m of the recorded parameters for uniform inflow along a horizontal wellbore. The evaluated values of spatial resolution are based on optimized logging speed, taking into account TA measurement specifics, well construction design, and total production rate. In this first field test of the innovative EXP in two horizontal wells producing water and oil at low rates, the tool was conveyed on coiled tubing and tractor. Joint interpretation of data recorded with the EXP and standard PL tools confirmed that the inflow profiles for each well along with profiles of phase velocities and water inflow zones were reliably established.