Leading the Way: Surveillance Planning and Integrated Interpretation for the First Low Tension Gas (LTG) Flooding Pilot in North Oman's Carbonate Field

Abstract The LTG approach employs surfactants to reduce the interfacial tension between water and oil, facilitating the mobilization of residual oil alongside foam for effective conformance control. This pilot was initiated to gather data to address critical remaining uncertainties and threats militating against full maturation of the opportunity. This paper sheds some light on the outcomes and insights extracted from the surveillance log data that played a crucial role in affirming if the first Oman foam pilot for LTG flooding is a success. Surveillance logging data played a pivotal role in determining the distribution of injected fluids and quantifying fluids saturation over the trial period. Advanced pulsed neutron technology and injection logging data from two wells within the carbonate field were utilized for the evaluation. The injection strategy for two wells comprised multiple cycles of immiscible Water-Alternating-Gas (WAG) injection using N2 to establish a baseline, succeeded by multiple cycles of Surfactant Alternating Gas (SAG) injection for foam generation. A comprehensive surveillance program was deployed for continuous monitoring of pressure responses, saturation profiles, injection conformance, and reservoir fluid dynamics, enabling a thorough assessment of the SAG flooding process. Injection Logging data was undertaken for conformance monitoring during the injection phase. Analysis of pressure and temperature data was performed before and after injections to identify any potential occurrences of crossflow during shut-in phases. Additionally, advanced pulsed neutron data was acquired to monitor changes in gas, oil, and water saturation over time following each injection stage. Interpretation of petrophysical advanced pulsed neutron and injection logging data, aided in assessing saturations within the relevant formations both before and after injections. Additionally, the injection logging data provided insights into injection intervals, assisting in the evaluation of fluid injection, and facilitating the planning of subsequent injection phases. The integration of these findings enabled one of the key project objectives to establish if foams can be generated during this LTG pilot process to be addressed. The pre job planning and real-time support for data acquisition, rush interpretation, and integration of findings enables the team to efficiently strategize operations at each injection. Successful integration of pulsed neutron data and PLT data with the help of advanced log interpretation helped to establish that foam was generated from Low-tension gas flooding process in the carbonate reservoir.