Fluid Characterization by Prompt Gamma-ray Neutron Activation Analysis (PGNAA)

I. Meric 1,2 , G. A. Johansen 1,2 , M. B. Holstad 2,3 , J. Wang 4 and R. P. Gardner 4

1. Department of Physics and Technology, University of Bergen, Allégaten 55, 5007 Bergen, Norway

2. The Michelsen Center for Industrial Measurement Science and Technology, P.O. Box 6031, 5892 Bergen, Norway

3. CMR Instrumentation, Christian Michelsen Research AS, P.O. Box 6031, 5892 Bergen, Norway

4. Center for Engineering Applications of Radioisotopes (CEAR), Nuclear Engineering Department, North Carolina State University, Raleigh, NC, 27695, USA

   
   

   Email: ilker.meric@ift.uib.no

ABSTRACT

Multiphase gas/ oil/ water measurement has been and still is a challenging task within the petroleum industry. The requirements to measurement efficiency and accuracy have been continuously increasing at the same time as the trend is to use subsea installations.

Previous work on the use of prompt gamma-ray neutron activation analysis (PGNAA) in conjunction with the so-called Monte Carlo Library Least Squares (MCLLS) approach in multiphase flow measurements have shown that the method could be feasible for determining the weight fractions of the constituents of a multiphase mixture.

In this work, however, the PGNAA method in conjunction with the MCLLS approach is initially being considered for a detailed characterisation of the water phase, also referred to as produced water in the terminology of petroleum. The feasibility of utilizing the PGNAA method for characterisation of produced water was to be studied through Monte Carlo (MC) simulations using a specific purpose MC code called CEARCPG. CEARCPG is also used to produce the elemental library spectra that are required in the MCLLS approach. The current status of the work and the results obtained through using the specific purpose code CEARCPG will be presented.

Keywords Prompt gamma-ray neutron activation analysis, monte carlo, fluid characterization, least- squares fitting, produced water