Allocation of Commingled Production Using a Geochemical Technique: From Inexpensive Tool for Production Monitoring
Mark A. McCaffrey, Mark A. Beeunas, Brooks A. Patterson, and David K. Baskin
OilTracers LLC, Dallas, TX
Because geochemical techniques allow allocation data to be collected at low cost, such geochemical data can be collected far more frequently than can data collected from production logging. For example, using a geochemical technique, an operator can determine the individual contributions of multiple reservoirs to the commingled production from a given well on more than 20 separate dates for a combined cost which is less than the cost of one production log run on one date. The greater frequency of data collection using the geochemical approach allows an operator to more easily identify production problems from a given reservoir using geochemical allocation data than using production logging data.
The geochemical approach to production allocation is also preferable to production logging because the geochemical technique can be used even in cases where production logging cannot (e.g., in wells with electrical submersible pumps, or in highly deviated wells, or in multi-lateral wells). The geochemical technique also does not interrupt production and eliminates the risk of sticking a logging tool.
Geochemical quantification of the contributions of multiple zones to a commingled oil stream, or a commingled water stream, or a commingled gas stream is readily achieved by identifying natural chemical differences between "end-member" samples (i.e., samples of the produced material from each of the zones being commingled). Parameters reflecting these compositional differences are measured in the end-member samples and in the commingled samples. These data and a linear algebra approach are used to mathematically express the composition of the commingled samples in terms of contributions from the respective end-member samples. These calculations are enabled by a commercially available software package, which is currently in use in numerous fields.
AAPG International Conference and Exhibition, Cape Town, South Africa 2008 © AAPG Search and Discovery