PNL case study

Combined interpretation of pulsed neutron and production logs as an integrated solution for hydrocarbon reservoirs

A client in the USA requested technical support to evaluate hydrocarbon zones across a complex and depleted reservoir. Anticipated low salinities and effective porosities values could create low contrast between water and hydrocarbon in situ (reservoir zones); therefore, the water saturation curve was expected to show some uncertainty. The basic petrophysics curves were calculated from open-hole logs provided by the customer. A Pulsed Neutron Log which was run in real-time mode in order to achieve a consistent saturation comparison, especially in environments of short reservoir sections and for proper monitoring of fluid contact movements inside the formation, demonstrated good consistency between Sigma, GR and Resistivity curves.

To determine the progress of water breakthrough in the producer well, it was decided to invite ANSA to evaluate the distribution of fluids within the reservoir. The PNL interpretation defined the proposed perforated intervals; however, after shooting activities, the well started with low production, and understanding where the hydrocarbons were produced, the effectiveness of the perforations, and the distribution of the hydrocarbon profile were the next steps to be resolved. Therefore, a Production Log was run to evaluate the production profile.

Integrating the datasets, combining the reservoir information with basic petrophysical interpretation, pulsed neutron, and production logging data yielded an understanding of well fluids saturation and production. It also provided added value by identifying the best interval reservoir zone opportunities to the client and, depending on each case, suggested perforating reservoir zones to get the best performance and productivity of the well and adjacent wells in this field. In addition, going forward, the data provided will be instrumental in developing a workover plan for the entire field.

ANSA team’s experience with Pulsed Neutron Logging guaranteed the success of the analysis as our experts were able to correctly understand fluid distribution within the reservoir, to maximise the productivity of the well, and find other opportunities based on increasing the hydrocarbon produced volume.

Finally, the customer feedback was: 

“The clear and concise analysis reports of pulsed neutron, production logging and reservoir analysis are exactly what we’ve come to expect from ANSA. Thank you for the great work. You’ve been an essential part of our developing business.”

If you need support with pulsed neutron log (PNL) analysis and/or a production logging (PLT) survey, get in touch with our team.