The field is located in the south of Sultanate of Oman and was discovered in 1980 The field produces from sandstone reservoirs a heavy crude with high viscosity (up to 2000 cP) value that contains no appreciable solution gas. Production is supported by a bottom active water drive aquifer. An unfavourable mobility contrast between the oil and formation water results in rapid water breakthrough and a large portion of a well's reserves are produced at high water cuts. The average economic limit of wells in the field is about 98% water cut. Thus, water management plays a key role in well economics. The new horizontal producer wells target is to drain by-passed oil with only 30 ~ 80 m spacing. Injectors are at the flank and are injecting deep into the aquifer. Water breakthrough occurs at high sand permeability and once happened; water will dominate well production due to unfavourable mobility ratio. Some of the new producer wells are completed with Wire-Wrapped Screen (WWS) – Stand Alone Screen, and swellable packers to isolate higher water-saturated zones. However, most of these wells start typically with a 60% water cut (BSW) or more and rapidly reach +90%. To overcome current reservoir/production challenges; The operator has used the latest Autonomous Inflow Control Device (AICD) Technology called Autonomous Inflow Control Valves (AICV). ICD's and previous generation Autonomous Inflow Control Devices (AICD) has shown in many cases increased oil production and higher recovery with better fluid influx balance along the well. However, neither ICD nor AICD can shut off the water production completely without well intervention. The AICV can restrict unwanted water significantly and autonomously. The AICV are based on different flow behaviour for laminar and turbulent flow that is utilized in a pilot flow to actuate a piston position to restrict unwanted fluids. The design with two parallel flow paths ensures the AICV is open for oil, and close for water autonomously. The AICV technology is based on Hagen-Poiseuille and Bernoulli's principles and is truly autonomous as it can identify the fluid flowing through it based on fluid properties such as viscosity, density and flowrate. For unwanted fluid such as water and Gas, AICV can generate enough force that will shut off the device if required. This makes it more robust than any other commercially available AICDs. AICV effect is reversible i.e. when the saturation of unwanted fluid (Sg or Sw) around the wellbore reduces, AICV will re-open for the oil production, thus draining all possible oil around the wellbore. In this paper, AICV performance will be discussed and comparative analysis with production performance of wells completed with WWS completed in the same reservoir will be presented. Based on the regular well testing and production analysis, it is evident that AICV technology has helped the operator in managing/shutting off the unwanted water production autonomously. This new AICV technology has the core application principles of ICD completions but the additional benefit of improved control/complete water shut-off without intervention; zero cost water shut-off operation and helps drain by-passed oil and thus maximizes recovery factors.

One of the largest clastic reservoir fields in the Sultanate of Oman has been discovered in 1980 and put on production in 1985. The field produces viscous oil, ranging from 200 - 2000+ cP at reservoir conditions. Over 75% of the wells drilled are horizontal wells and the field is one of the largest producers in the Sultanate of Oman. The field challenges include strong aquifer, high permeability zones/faults. Due to large fluid mobility contrast, the fields have experienced in pre-mature water breakthrough that has resulted in very high-water cuts. The average field water cut for open hole horizontal well after 6-9 months of production is over 94%. This paper details a meticulous journey in qualification, field trials followed by field-wide implementation and performance evaluation of Autonomous Inflow Control Valve (AICV) technology in reducing water production and increasing oil production significantly. AICV can precisely identify the fluid flowing through it and shutting-off the high water or gas saturated zones while producing oil from healthy oil-saturated zones. Like other AICDs (Autonomous Inflow Control Device) AICV can differentiate the fluid flowing through it via fluid properties such as viscosity and density at reservoir conditions. However, AICV's performance is superior due to its advanced design based on both Hagen-Poiseuille and Bernoulli's principles. This paper describes a comprehensive AICV completion design workflow that was developed across a multi-disciplinary team. Some of the initial wells completed with AICV has shown the benefit of accelerating oil production of over 30,000 bbls within the first few months of installation. Many wells started with 5-10 % water cut and are still producing with low water cut and higher oil production. The operator has approved AICV technology based on techno-commercial analysis and its positive impact on the project such as accelerated oil production and lower cost of water handling at the surface. AICV also helped in mitigating the facility constraints of handling produced water which resulted in reduce OPEX as allow the operator continued to drill horizontal wells. At the time of writing this paper, the operator has completed several dozen wells in the field with AICV technology and has an aggressive long term plan to complete several new and old wells. Finally, this paper also discusses in detail the comparative analysis of AICV wells for different subsurface conditions and share some lessons learned to further optimise the well performance. The technology has a profound impact on improved sweep efficiency and as well plays an instrumental role in reducing the carbon footprint by reducing the significant water production at the surface. It is concluded that AICV is a cost-effective field-proven technology for the water shut-off application. Due to its ability to autonomously identify and shut off water and gas production, the AICV technology has been approved to use as full fields implementation and in other fields. Field Background and Reservoir/Production challenges The operator produces around nine barrels of water against each produced barrel of oil. In general, the water produces to the surface with hydrocarbons contains many chemicals, which are usually not environmentally friendly and required additional treatment which increases the disposal cost. The Operator was looking for a cost-effective and proven technology that can control/shut off water production and improve oil production. The fields have a strong bottom aquifer and heterogeneous reservoir properties, such as permeability and downhole water saturation profiles. The challenge with matured brownfields, typically newly drilled wells will have pre-mature water breakthrough within few months of production. The fields have a highly viscous oil, with viscosity ranges from 200 cP up to 2000 cp at downhole conditions, thus creating a high mobility contrast between the oil and water, causing water fingering and coning at an early stage of production. These production challenges cause a significant recoverable oil left in the reservoir i.e. bypassed oil. Furthermore, excessive surface water production affects the integrated production system back pressures and flow, as well as an individual well's dynamics and pump efficiencies. This also has a significant downstream impact, where substantial investment is needed to handle, treat, and dispose of the water. Reducing these water volumes at the surface adds up to a tangible reduction in OPEX for water processing as well as environmentally friendly and assist the reservoir to maintain the reservoir pressure and energy by keeping the water in the reservoir. (Hilal et al 1997, Hassasi et al 2020)

One of the largest operators in the Sultanate of Oman discovered a clastic reservoir field in 1980 and put it on production in 1985. The field produces viscous oil, ranging from 200 - 2000+ cP at reservoir conditions. Over 75% of the wells drilled are horizontal wells and the field is one of the largest producers in the Sultanate of Oman. The field challenges include strong aquifer, high permeability zones/faults and large fluid mobility contrast have resulted that most of the wells started with very high-water cuts. The current field water cut is over 94%. This paper details operator's meticulous journey in qualification, field trials followed by field-wide implementation and performance evaluation of Autonomous Inflow Control Valve (AICV) technology in reducing water production and increasing oil production significantly. AICV can precisely identify the fluid flowing through it and shutting-off the high water or gas saturated zones autonomously while stimulating oil production from healthy oil-saturated zones. Like other AICDs (Autonomous Inflow Control Device) AICV can differentiate the fluid flowing through it via fluid properties such as viscosity and density at reservoir conditions. However, AICVs performance is superior due to its advanced design based on Hagen-Poiseuille and Bernoulli's principles. This paper describes an AICV completion design workflow involving a multi-disciplinary team as well as some of the field evaluation criteria to evaluate AICV well performance in the existing and in the new wells. The operator has completed several dozens of production wells with AICV technology in the field since 2018-19. Based on the field performance review, it has shown the benefit of accelerating oil production as well as reduction of unwanted water which not only reduces the OPEX of these wells but at the same time enormous positive impact on the environment. Many AICV wells started with just 25-40 % water cut and are still producing with low water cut and higher oil production. Based on the initial field-wide assessment, it is also envisaged that AICV wells will assist in achieving higher field recovery. Also, AICV helped in mitigating the facility constraints of handling produced water which will allow the operator continued to drill in-fill horizontal wells. Finally, the paper also discusses in detail the long-term performance results of some of the wells and their impact on cumulative field recovery as well as lessons learned to further optimise the well performance. The technology has a profound impact on improved sweep efficiency and as well plays an instrumental role in reducing the carbon footprint by reducing the significant water production at the surface. It is concluded that AICV technology has extended the field and wells life and proved to be the most cost-effective field-proven technology for the water shut-off application.