Water conformance is a common challenge in oilfield industry especially in water flood and active water drive reservoirs where water production has a significant impact on production economics, oil recovery and facilities constraints. Water shut-off (WSO) is an essential solution to delay or minimize water production however effectiveness depends on treatment efficiency. This abstract will demonstrate extensive mechanical and chemical WSO experience in horizontal drilled wells completed with passive Inflow Control Devices (ICD) completions, with case histories from North Kuwait giant water aquifer reservoir.
The main challenge during water conformance treatment is the proper diagnosis and the full understanding of the water flow profile; accurately identify the water source as well as reservoir understanding will help selecting the efficient WSO mechanism, which is crucial for a sound decision making considering the associated cost and the operational complications. Understanding reservoir geology, Integration of inflow profiling via Horizontal PLT and new technologies of water saturation logsare key to accurately identify the water source (heal, middle or toe side) and by turn WSO mechanism. This is done in integration of multidisciplinary domains of G&G, production and reservoir engineers and operation teams.
Mechanical WSO using inflatable packers’ technologies were applied for isolating the toe side, while chemical WSO technologies used for heal side isolation in the open-hole passive ICD completions. Rig-less shifting of ICD sleeves used where active SSD-ICD's completion installed. The statistics of executed WSO results of many case histories have shown relatively good success ratio represented in reducing water cut from 80 – 90% down to 20 – 70%, increase oil production rate from 200 bopd up to 3000 bopd in some wells depending on water source. Furthermore, WSO enabled bringing some inactive high-water wells back to production. This helps extending well-life and by turn maximizes ultimate hydrocarbon recovery. Also, reducing the total water production to facility allowed increasing production of some other wells producing to same facilities. As key learnt lesson; managing the produced liquid rate and drawdown post WSO is essential to maximize the benefit of WSO and delay sharp increase of water cut.
WSO solutions are in constant improvement. Integrating reservoir characterization, fluid inflow profiling and proper selection of WSO technique is crucial for any successful WSO decision. WSO became a common practice to maximize the oil recovery factor from Lower Burgan reservoir of North Kuwait fields.