Water injection is the most commonly used method for pressure maintenance in depletion drive reservoirs worldwide and there are numerous examples where the recovery has been enhanced significantly. However early breakthrough of injected water due to high permeability zones or thief zones mostly in heterogeneous carbonate reservoirs causes water recycling resulting in poor volumetric sweep and in turn adversely affects the oil recovery from the reservoir. A judicious mixture of proper reservoir management and development strategy may reduce the water recycling to a significant level. Sabiriyah Mauddud is a giant carbonate reservoir in North Kuwait and has been under production since last 57 years. Historical performance indicated very little aquifer support for the reservoir with no water production. A water flood pilot was initiated in 1997 when the reservoir had produced only 1% of its oil in place and pressure declined from its initial value of 3700 psi to the level of 2600 psi. Currently, the reservoir is under water flood with inverted 9 spot patterns in the crestal part and peripheral injection mainly in the western flank area. The water cut has gone up to the level of 42% after only low current oil recovery. High water cut is attributed to poor sweep efficiency due to preferential movement of water from conventional injector to producer through high permeability streaks/thief zones in the crestal area. As short term measure, a conformance plan to shut off the water contributing layers was prepared and has been introduced in the wells worked over during the period. Simulation run shows reduction in water cut by 5% by adopting the conformance plan. The new development strategy formulated for the field is to inject low and produce high from the reservoir and shifting the focus from crestal to peripheral injection. All the producers are planned to be completed with inflow control device to control the water production through the wells. The recently drilled producers are showing positive results and it is expected that the measures taken will help to maximize the benefits of water injection. The learning and the water flooding experience gained will be a valuable input for other reservoirs under water flooding.

After 40 years of depletion drive, a mature, giant and multi-layer carbonate reservoir is developed through waterflooding. Oil production, sustained through infill drilling and new development patterns, is often associated with increasingly higher water production compared to earlier development phases. A field re-development plan has been established to alleviate the impact of reservoir heterogeneities on oil recovery, driven by the analysis of the historical performance of production and injection of a range of well types. The field is developed through historical opportunistic development concepts utilizing evolving technology trends. Therefore, the field has initially wide spacing vertical waterflooding patterns followed by horizontal wells, subjected to seawater or produced water injection, applying a range of wells placement or completion technologies and different water injection operating strategies. Systematic categorization, grouping and analyzing of a rich data set of wells performance have been complemented and integrated with insights from coarse full field and conceptual sector dynamic modeling activities. This workflow efficiently paved the way to optimize the field development aiming for increased oil recovery and cost saving opportunities. Integrated analysis of evolving historical development decisions revealed and ranked the primary subsurface and operational drivers behind the limited sweep efficiency and increased watercut. This helped mapping the impact of fundamental subsurface attributes from well placement, completion, or water injection strategies. Excellent vertical wells performance during the primary depletion and the early stage of water flooding was slowly outperformed by a more sustainable horizontal well production and injection strategy. This is consistent with a conceptual model in which the reservoir is dominated by extensive high conductive features that contributed in the early life of the field to good oil production before becoming the primary source of premature water breakthrough after a limited fraction of pore volume water was injected. The next level of analysis provided actual field evidence to support informed decisions to optimize the front runner horizontal wells development concept to cover wells length, orientation, vertical placement in the stratigraphy, spacing, pattern strategy and completion design. The findings enabled delivering updated field development plan covering the field life cycle to sustain and increase field oil production through adding ~ 200 additional wells and introducing more structured water flooding patterns in addition to establishing improved wells reservoir management practices. This integrated study manifests the power, efficiency and value from data driven analysis to capture lessons learned from evolving wells and development concepts applied in a complex brown field over six decades. The workflow enabled the delivery of an updated field development plan and production forecasts within a year through utilizing data analytics to compensate for the recognized limitations of subsurface models in addition to providing input to steer the more time-consuming modeling activities.