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The X field is a mature oil field producing with water injection in place. As part of a phased development, in Phase Two, two infill wells were planned and drilled to extract incremental recovery from a discovered undeveloped reservoir. This includes planning two horizontal producer wells requiring active real time geosteering utilizing deep resistivity tool technology. The wells’ objectives are to ensure the well placement was in an optimal location and to maintain the trajectory within a reservoir that is approximately 100ft thick and was believed to be homogenous field wide. The main challenge to this feat is the faulted nature of the field and the uncertainty in reservoir thickness and extend due to limited well penetrations at this reservoir level. During the planning phase, it was identified early that a deep resistivity tool would be beneficial in geosteering the wells. Prior to drilling, an integrated pre-job model was designed to test multiple tool settings and subsurface scenarios to strategize an execution plan identifying key points where there is a need for real time trajectory adjustments and to pre-plan alternative trajectories based on subsurface scenarios to enable efficient turnaround time to react to real-time results. Conventional navigation tools yield only a shallow to medium depth of measurement (~15ft) which would not have met the objectives of the well given the geological complexities (high fault offsets, laminated reservoirs) and well design (high angle to horizontal). The ultra-deep resistivity (UDR) tool was employed instead to enable trajectory optimization with up to ~100ft depth of investigation (DOI), using a multi-frequency, multi-spaced antenna design from medium and long spaced transmitter receiver spacings providing up to 9 vector components. In real time, the 1D inversion (using 5 of the vector components) was used for early sand and fluid contact detection. During execution, the same integrated team was monitoring the well and close interaction between the subsurface, geosteering and directional drilling team was a key requirement to ensure drilling of the well was safely and objectively executed, especially with the challenges posed with virtual working through a pandemic. As is when dealing with subsurface uncertainties, there were numerous surprises encountered during the drilling of the horizontal wells. Particularly in the matter of fault throw uncertainty and sand distribution. The initial 1D real-time UDR results were able to assist in real-time trajectory adjustments and to provide some geological understandings with regards to fault throw and location of possible faults along the well bore which were then confirmed with borehole image logs. Additionally, 3D inversion images were processed post drilling, and further geological insights were discovered with regards to the depositional trends on the reservoir. In a reservoir that was initially thought to be sand-rich and homogenous, 3D inversion suggests evidence of possible channels. This revelation could explain the varying thickness of the reservoir that was observed during drilling on the 1D UDR canvass. There are plans for future work to incorporate the observations and the analysis of the UDR products for deeper reservoir understanding of the field. Studies to include full integration with seismic data and production data would prove beneficial in well and reservoir management. Additionally, insights gleaned from the optimized selection of tool frequency for real time use and calibration with azimuthal dips and images proved invaluable especially in resolving unexpected structural and depositional complexities. The challenges in delineating fluid contacts in a structurally complex reservoir was also apparent with multiple realizations (and associated probabilities) of contacts seen from the real time results, which proved valuable in re-affirming the difficulties in characterizing the uncertainties in the field

M field is a faulted anticline structure that lies in a deepwater turbidite environment. Field Development started in late 2016, with 10 oil producers and 2 water injectors. Within 2 years of production, significant GOR increase in some of the wells led to production curtailment, which has impacted the field production promise. Poor injectivity seen in one of the water injectors also led to an assumption of compartmentalization or sandface plugging/damage that required investigation. In order to evaluate intervention opportunities to mitigate against the high GORs and to determine the cause of the poor injectivity, production logging tools were proposed in four candidate wells. The objectives of the logging campaign were: To understand the gas influx profile into the well and how different compartments are contributing to the GOR Assess behaviour of G/O, O/O, O/W crossflows and their impact on reservoir depletion profile Aid decisions in requirements for downhole controls (i.e. AICD placement) vs surface controls Provide opportunity to couple PL logs with PNC logs to identify potential GOCs, estimate gas/water saturations and determine if there are any bypassed oils Based on the candidate wells, the following challenges were present: Highly-deviated/horizontal wells requiring complex conveyance solutions Multiphase flows (gas, oil and potentially water) in highly deviated conditions which further complicates fluid phase contribution calculations and velocity modeling Rig up height limitations on the platform which requires shorter logging tool strings High flowrates with tool lift limits requiring careful modelling work to ensure risks are understood and minimized In view of these challenges, a new Array Production Logging Tool (henceforth called New-APLT) was proposed as an alternative to the previous generation APLT. It has a more robust design with co-located sensors in a single module with additional optical sensors that improves flow measurement and gas detection. Additionally, screen tracers sampling was proposed in one well, which would help calibrate the tracer interpretations against actual fluid rates. The novel approach and synergistic efforts amongst many disciplines led to a successful execution of the logging campaign, and the first ever deployment of the New-APLT tool on e-line tractor. The timely results from the campaign which coincided with a 4D seismic acquisition has helped to justify downhole control options for some of the wells, and potentially helped to avoid costly remedial work on the water injector. The valuable dataset will also influence the infill development well campaign location, design and well count.