Advanced Pulsed Neutron Logging Behind Casing in Rig-Less Operations Enables Bypass Pay Identification and Hydrocarbon Quantification for Abu Qir in Offshore Egypt
Authors: Gomes Renata , Vazquez Maria Leticia , Labib Amr , El-Dabbour Mohamed , Shalaby Hany , Elshater Khaled 
Published: October 2024

Objectives/Scope

This paper exemplifies how a sophisticated pulsed neutron logging technology has proven extremely valuable in locating and analyzing a gas-bearing reservoir in an environment with complex completions and low-formation water salinity.

For oilfield operating companies, the most promising sources of future earnings are wells that have already been drilled and are producing. These wells must continue to produce at optimal economic rates throughout their lives.

Understanding reservoirs' current fluid saturation situation is a pivotal step in planning a well workover to boost production when required. This understanding is often obtained through formation evaluation based on cased-hole (CH) logging.

Traditionally, Abu Qir-ENERGEAN operations are conducted by offshore rigs. Mobilizing a jack-up rig without full assurance of economic gain is costly, inefficient, and increases the company's CO2 footprint. An existing targeted well comprises two reservoir sections; Abu-Qir is required to evaluate the potential of the reservoir situation and re-complete the well to add the upper reservoir section.

The targeted well was crucial to the client, and the confirmation of bypassed hydrocarbon would be the client's trigger for re-completing the well. Due to the complexity of the environment, a new generation of pulsed neutron logging tool providing fast neutron cross-section measurement (FNXS) that is sensitive to gas volume was the best option for the job.

Methods, Procedures, Process

The proven strategy of employing an innovative pulsed neutron logging and interpretation technology lowers operational risks and costs as it could be deployed in a rig-less environment. A rich dataset was obtained, which included capture and inelastic elemental spectroscopy, fast neutron cross section (FNXS), and self-compensated sigma and neutron porosity logs. The logs were interpreted by combining the neutron porosity and FNXS with matrix characteristics and mineral dry weight fractions from elemental spectroscopy processing.

Results, Observations, Conclusions

The logging objectives were successfully met, and valuable information about the reservoir was determined efficiently in a rig-less environment. This allowed the operator to plan for the workover operations while reducing the cost of rig operations.

The production of this well had significantly increased after the implementation of the workover plan.

The collaboration and technical discussion to run the new generation pulsed neutron logging tool directly resulted in eliminating uncertainty in operations and reducing emissions, as the tool was deployed rig-less. This was also a great cost savings and a key de- risking factor for proceeding with the well activity, knowing that the hydrocarbon saturation still existed behind the casing.

The direct results of running the new generation pulsed neutron logging tool rig-less were time-saving and accurate hydrocarbon estimation, which positively impacted suitability and resulted in a major reduction of CO2.