Diagnostics of Data Quality for Analysis of Production Data

Nobakht M., Mattar L., Fekete Associates Inc.

This paper is accepted for the Proceedings of the Canadian International Petroleum Conference (CIPC) 2009, Calgary, Alberta, Canada, 16-18 June 2009.

Analysis of production data for characterization of reservoirs is becoming more popular. Sophisticated tools and methodologies exist to extract permeability, completion effectiveness and pore volume from production data (rates and flowing pressures). Often, in practice, these are the only tools available, especially in the case of low permeability reservoirs where it is not practical to conduct buildup tests.

Production data, though plentiful, can be of poor quality because of operational problems, or changes in operating conditions, which are usually not documented (re-completions, tubing change-outs, compression, liquid loading, pressure or rate averaging…). If this poor quality or inconsistent data is not recognized as such, it can easily be misinterpreted as being a r eservoir issue rather than the operating problem that it is. For example, liquid loading, if not recognized, may be misinterpreted as interwell interference or reservoir depletion.

In this paper, we review many of the operating problems we have observed in practice, and we discuss ways and patterns for recognizing them as operating issues rather than reservoir phenomena. Diagnosis of production data quality is a critical and necessary step that must precede any interpretation of production data. Recognition of inconsistent data is not always an easy task, and requires a lot of experience. The diagnostics presented in this paper will help the engineer in recognizing these problems, and potentially avoiding misinterpretation of the data.