Understanding Fluid Contact Distribution Using Ultra Deep Resistivity Reservoir Mapping Tool in Carbonate Reservoirs of a Green Oilfield
Authors: Basri Muhammad Walfajri , Almarzouqi Hamed Ali , Sugama Candra , Rashid Atiqurrahman Bin Abd , Alnaqbi Meera , Suleiman Sameh Yahyia Ali , Bourgeois Daniel , Siddiqui Wamiq , Adetunji Damilola 
Published: May 2024

Abstract

Objectives/Scope
This paper presents an application of Ultra Deep Resistivity tool in a new onshore oilfield with complex carbonate reservoir to understand Oil Water Contact distribution in a lower cretaceous carbonate reservoir. The field is being developed under water injection since beginning of development; however, water production is the main challenge of the reservoir productivity. The field is also complex in structural geology point of view; the water produced also came from faults/fractures communication. Reservoir Mapping While Drilling techniques was chosen to know Oil Water Contact position in 8 ft TVD of target reservoir.

Methods, Procedures, Process
After conducting pre-job modeling and analyzing historical data, the reservoir Mapping While Drilling (RMWD) technology was chosen to achieve the well's objectives. This technology can provide high-definition multi-boundaries reservoir mapping, thin-layer delineation, and can detect depths greater than 250ft. The RMWD service relies on automated multi-layer inversion of Deep Directional Electromagnetic Measurements. This technology boasts a Depth of Investigation of more than 100ft, allowing for mapping of multiple layers and features, including OWC, at the reservoir scale. Furthermore, it bridges the gap with seismic surface interpretation.

Results, Observations, Conclusions
The interpretation of the inversion mapping showed a resistive target, low resistive transition zone and a water/flooded zone. Water flooding was detected at distances up to 42ft TVD from the borehole. The transition zone can be clearly seen between the target and water zone with low resistivity. Also using high-definition inversion, the structure of reservoir can be clearly defined as anticline, without faults and thickness of target estimated. Using reservoir mapping of target and density image, the structure of the reservoir can be defined and observed to be up dipping at the start of drilling and down dipping by total depth. Having a comprehensive knowledge of both the complete reservoir and the flooded zone is essential for effective production and planning future development strategies. By combining information from the reservoir level to the borehole level, it becomes possible to accurately map out the various reservoir layers, transition zone, flooded zone, target thickness, and overall structure.

Novel/Additive Information
To achieve the production target, horizontal oil producers equipped with ESP and horizontal water injectors located in the flank zone for pressure support was defines as the development scheme. Distributed sensing temperature completion is being implemented in some key water injector wells to optimize water-flooding surveillance. The field is being developed under water injection in three reservoirs since beginning of development; however, water production is the main challenge of the reservoir productivity. This oil field is relatively new development, with production started in 2017 from three reservoirs without inactive string since 2021.