Tursinbayeva, Damira (Tengizchevroil) | Lindsell, Karl Michael (Tengizchevroil) | Zalan, Thomas Anthony (Tengizchevroil) | Dunger, Darrin Allen (Chevron Corporation) | Kassenov, Baurzhan (University of Tulsa) | Howery, Randy (Tengizchevroil)
Over the field life, surveillance in Tengiz oil field has provided historical and baseline data for simulation history matching, static and dynamic reservoir characterization and modeling, and the foundation for efficient well management. Hence, it continues to be an important part of everyday field operations. At the surveillance planning stage, the comprehensive opportunity list of well candidates is developed based on input provided by members of multiple teams: geologists and petrophysists, production and reservoir engineers, drilling and field operations specialists. SCADA system, permanent downhole gauges (PDHGs) and multiphase flow meters (MPFMs) are widely implemented for production data acquisition and analysis. However, the majority of surveillance activities still need well intervention into the high pressure, high H2S concentration wellbores, often during harsh weather conditions. Each job execution plan is therefore focused on the safest procedure to obtain the necessary data. Each planned survey in the surveillance plan is ranked according to the value of information to be obtained, in order to help schedule the timing of surveillance based on plant production needs.
The ultimate goal is to safely execute planned surveillance to support production optimization and field development work. This paper will highlight TCO success in addressing the different reservoir and well production uncertainties through a properly designed surveillance plan with both short and long-term objectives.
Badruzzaman, Ahmed (Chevron ETC) | Crowe, John (Chevron) | Bean, Clarke (Chevron Asia South) | Logan, James P. (PT Caltex Pacific Indonesia) | Zalan, Thomas Anthony (Pearl Oil Thailand Ltd) | Platt, Christopher J. (Chevron Indo Asia BU) | Adeyemo, Adedapo
Pulsed neutron measurements are commonly used to locate gas behind casing and quantify steam saturation, but do not always yield desired results. Several parameters are utilized to identify gas and one parameter, the thermal neutron capture cross section, Sigma, is used to compute steam saturation. In the paper we report a mixed experience in identifying gas with these techniques, across fields, tools and vendors. Some parameters have worked well in some cases but have performed poorly in others. The uncertainty in steam saturation, computed using Sigma, is greater than those previously reported elsewhere. Modeling offers insight into the mixed results. It appears that in some cases the PNC-derived Sigma may yield erroneous steam saturation for a variety of reasons, including uncertainties in the input parameters and possibly an inherent nonlinear transport effect that increases as steam saturation increases. An alternative approach based on PNC pseudo-porosity is explored. Calibration of cased-hole tools in gas reservoirs, generic and local, open-hole baseline data and core analysis of complex rocks are essential. Currently, these are either nonexistent or infrequent.