Increasing Production Capacity of a Low Resistivity Pay Reservoir Associated with a Highly Flooded Environment in a Fault Corridor – A Successful Case History from UAE Onshore

Maximizing reservoir exposure in a low resistivity pay reservoir located in a fault corridor along the flank of a brownfield is tremendously challenging. Additionally, the high uncertainty associated with two uneven types of waterfronts, in the form of water slump/reverse conning and front water moving along the planned wellbore, poses a risk of derailing the well objective and compromising well performance. It was critical to consider the right application to mitigate these challenges to achieve the well objective. Considering the subtle log responses in the reservoir, the only differentiating parameter to consider for well placement with confidence was the resistivity changes within the reservoir. The variation in resistivity was either related to saturation differences or lithological units. Mapping the resistivity profile around the wellbore and defining the reservoir properties would be possible by utilizing a tool with a greater depth of detection integrated into a conventional triple combo Bottom Hole Assembly (BHA). Extra Deep Azimuthal Resistivity (EDAR), with its lower frequencies and flexible spacing between transmitter and receiver, delivers the required large Depth of Detection (DOD). This measurement was considered to provide the required saturation and bed boundaries solution. Mapping the changes in resistivity above and below the well path facilitated informed well placement decisions to maximize reservoir contact and navigate within the optimum resistivity of the reservoir. Utilizing the EDAR application in this well proved to be highly beneficial in placing the well in the oil column of this low resistivity pay reservoir. It mapped the water slumping intervals from the above unit and the change in water level from below the well path. It mapped two faults that displaced the well from its original primary target to the upper secondary target. Based on the boundaries mapped, the throw of the faults was estimated, and the well bore position was established. The EDAR inversion mapped an increase in water saturation from both the top and bottom. Based on this information, total depth (TD) was declared ~400 ft earlier than planned. The intervals of water slumping and elevated water zones below the trajectory were considered when optimizing the lower completion designs.