Production-Well-Testing Optimization With Multiphase Flowmeters
Authors: Denney Dennis 
Published: February 2015

This article, written by Technology Editor Dennis Denney, contains highlights of paper SPE 101475, "Production-Well- Testing Optimization Using Multiphase Flowmeters," by M. Metwalli Hassan and M. Bekkoucha, Adco, and M. Abukhader, Schlumberger, prepared for the 2006 Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, UAE, 5-8 November.
Production testing by use of portable multiphase flowmeters (MPFMs) was implemented in Abu Dhabi Co. Onshore Oil Operations' Field B. The objectives were to quantify the water and gas production, evaluate the performance of slugging and intermittent wells for procurement actions, evaluate the production-test data measured with conventional test separators, and improve the testing duration and strategy. The program included a set of elements to qualify the MPFM results before use and considered parallel testing with conventional separators to enable fair comparison of results.

Introduction
Field reports indicated that the actual production volumes of oil, water, and gas from the B field do not match theoretical volumes calculated from well-test results measured with test separators. This mismatch of production data is reflected in the accuracy of reconciled production allocation on a per-well basis and the reservoir basis. Production performance and well-diagnostics analysis were other issues that affected reservoir-management decisions and proactive procedures, especially for high-water-cut and high-gas/oil-ratio (GOR) wells. Monitoring of the slugging and intermittent wells also was a problem for test separators. Accurate production data are required for numerical simulation, reserves calculations, and optimization of reservoir-data acquisition.
MPFM Application. The MPFM testing campaign in the B field was implemented initially in oil-rim reservoirs similar to that shown in Fig. 1. Wells in these reservoirs have severe reservoir-pressure depletion, high water cut (10 to 60%), and GORs ranging from 2,000 to 20,000 scf/STB. The oil rims are thin reservoirs (30 to 60 ft) and are narrow. Oil rims are saturated-oil reservoirs, and both the gas cap and the oil zone are produced without pressure maintenance. Therefore, most of the wells in these reservoirs experience either intermittent or slugging production. Testing these wells with conventional separators indicated unstable production rates and erroneous measurements of oil, water, and gas rates. Accordingly, these wells were given priority for testing by MPFM.

MPFM Used
The meter is a portable phase-tester venturi meter. It is an in-line MPFM capable of operating under a large variety of conditions. The venturi meter has two main sections: the measuring section and the data-acquisition flow computer.
The measuring principle is based on a total-mass-flow rate measured with a venturi meter. The individual-phase fractions (oil, water, and gas) are measured with a dual-energy gamma-fraction meter. The data are processed in the data-acquisition flow computer, which computes the line pressure and temperature and the individual-phase flow rates.