Oil and Natural Gas Corporation (ONGC) operates the Vasai East Field in western offshore India. The reservoir is challenging to drill and complete because of the inherent risks of gas and water coning, permeability differences, and declining reservoir pressures. An innovative horizontal completion strategy for new wells to meet the many unusual challenges was required. The need for appropriate zonal isolation was identified after the wells in the Vasai West Field had been completed without segmentation in the open hole. The requirements included:○Oil production without breakthrough of gas or water○Effective hydraulic seal in washed-out hole conditions○Contingency options for intervention, if needed○Equipment to withstand high bottomhole static temperature. This paper describes how the challenges were met using swellable-packer, high-temperature isolation systems placed between perforated tubing/sliding-sleeve circulating devices and blank pipe spaced out across the oil-bearing zones. The swellable packer systems were located at the ends of each facies change to isolate the local high-permeability zones. Swellable packers use expanding rubber around the packer mandrel that expands to seal the annulus and create a permanent seal when it contacts liquid hydrocarbon or water in both cased or openhole environments. Five wells have been completed in Vasai East field to date with swellable packers in conjunction with pre-perforated liners or sliding sleeves. PLT logs have been run in one of the wells post completion, and isolation has been verified. Low water cuts and low gas/oil ratios (GOR) also verify that the packers isolate the various sections of the wells as planned. On the success of these completions, this technology is currently being planned for ONGC's completions in other fields. Introduction The Vasai East Field is located in the Heera-Panna-Bassein block and falls toward and northeast of the main Bassein field about 80 Km west northwest of Mumbai city (Fig. 1). Water depth varies from 40 to 50 m. As per the latest geological model, the field has an average oil column thickness of about 28 m trapped between the gas cap above and aquifer at bottom. The field extends over an area of 54 sq. km. Vasai East field was discovered in 2001 and had continuously declined in pressure due to gas production from the nearby Bassein field. Both the fields are hydro dynamically connected through a common aquifer (Fig. 2). The production targeted was from a thin-oil column trapped between a gas cap and water at bottom in a high-temperature reservoir. The field had been plagued with problems from severe mud loss that had occurred during exploratory drilling in the field. Also, since the oil is between the gas cap and aquifer at bottom, the horizontal drain-hole placement was critical to control unwanted gas/water production. The Vasai East Field is hydro-dynamically connected with the main Bassein field through a common aquifer, which is depleting due to constant gas production. Therefore there was an urgent need to quickly develop this field. To keep pace with the quickly depleting reservoir pressures, efforts were made to expedite the development scheme for the exploitation of oil from this field. The Vasai East Field is separated from the main Bassein field by a low axis at the Bassein formation level.

Inflow control device (ICD) technology helps in balancing the production across the entire interval, addressing some of the challenges associated with horizontal and deviated wells. Nevertheless, ICDs have limited capabilities in identifying and restricting unwanted fluids upon breakthrough. Autonomous ICD (AICD) technology functions similar to an ICD initially (i.e., balancing flux across the length of horizontal wells, effectively delaying breakthrough) but has the additional benefit of restricting the flow of unwanted fluids upon breakthrough. Multiple AICD case histories highlighting the benefit of the technology in mitigating well performance challenges and delivering improved recovery throughout the life of the well are discussed. AICD technology is fluid dependent, principally reacting to the properties of the fluid flowing through it and creating an additional pressure drop to restrict the production of unwanted fluids. The fluidic diode-type AICD has no moving parts and uses flow dynamic properties to distinguish between the fluids. It uses downhole fluid properties to accurately differentiate between oil, water, and gas; and changes the flow path autonomously to restrict unwanted fluids upon breakthrough; and uplifts oil production from the oil-saturated zones across the wellbore. Extensive testing has been completed to characterize and accurately predict the flow performance, which enables designing an AICD completion efficiently. Flow performance analysis of the various types of fluidic diode AICDs designed to address various well performance challenges [i.e., high gas-oil ratio (GOR) or high water production or both, increasing oil production] is discussed. The flow performance analysis has been derived using extensive and rigorous single-phase and multiphase flow-loop test programs, covering the wide range of oil properties. This paper will also highlight the screening criteria in selecting a candidate well for fluidic diode AICDs application. Furthermore, the paper will also discuss in detail a reservoir-focused well-centric completion design workflow for designing fluidic diode-type AICD completions for a candidate well. This collaborative workflow takes into account the various subsurface and well attributes to meet or exceed well key performance indicators (KPIs) over the life of the well. It can be observed from the results of various field installations and production data analysis that installing AICDs during the early life of wells or fields results in a higher ultimate recovery (UR) compared to installing it in brown or matured fields. However, the recovery with AICD in brown/matured fields can be higher than ICD or any other legacy openhole completion. The fluidic diode AICD design methodology and field installation results for AICD technology in different completion designs, such as openhole gravel pack, open hole, retrofit, artificial lift completion, and multilateral wells, are discussed as well. Additionally, it will also discuss the entire cycle—from flow-loop testing, candidate well selection, pre- and post-drilling AICD well modeling and design, calibration, and post-installation well performance reviews for an efficient and valid evaluation of the technology.

Production in the Upper Burgan reservoir began in the Raudhatain and Sabriyah fields in 1959 and 1970, respectively. However, significant quantities of original oil remain in the reservoir; although the Upper Burgan fields have both been in production for more than 56 years, the offtake to date is a relatively small percentage of the potential ultimate recovery. The sandstone of the Upper Burgan is typically fine grained. Porosities average 25% and can reach 30% in the best quality sands. Horizontal permeability values of 200 to 700 md are common, with variation in vertical permeability caused by changes in the texture and structure of the reservoir. In 1995, the operator initiated a strategy to significantly increase production from these North Kuwait fields by integrating a multidisciplinary team from within the operating company. Waterflooding was part of the Upper Burgan development plan, during which the heterogeneous reservoir was expected to encounter early water breakthrough compared to other North Kuwait reservoirs. After 20 years of waterflooding in the Upper Burgan, the water cut reached 50%, and water management became crucial with reduced hydrocarbon recovery from the field. Autonomous inflow control device (AICD) technology with screens was installed in a pilot well in the Upper Burgan reservoir to help reduce the water production and increase the oil recovery from the well. AICD technology uses fluid dynamics technology to differentiate the fluids flowing through the device. When water breaks through, the AICD creates a pressure drop to restrict production flow at that device, favoring the production of the healthy oil-statured zone, thus increasing expected ultimate recovery from the well. The AICD has no moving parts, electronics, or connections to the surface and employs a unique geometry that alters the flow path within the tool upon water and/or gas breakthrough. This technology has helped improve recovery by reducing water cut from the high water-saturation zones, thereby increasing the overall oil recovery from the well. Forecasted well performance with AICD technology is in line with actual production and water cut.

In heavy oil fields, well longevity is limited by water inflow. Passive inflow control devices (ICDs) are effective in terms of balancing production flow and delaying the onset of water production. Nevertheless, when gas and/or water breakthrough occurs, a passive ICD enables production of the unwanted fluid. Autonomous ICDs can provide additional restriction to the unwanted fluids and can further enhance the production of oil. The fluidic diode autonomous ICD is functionally based on fluid dynamics technology in which internal geometry directs flow movement based on the viscosity of the fluid. The autonomous ICD enhances oil production while restricting water and gas influx, without the requirement of intervention or moving parts within the device. The result is improved sweep efficiency, which can extend well life and thereby assist in reducing operating costs. Effective design of an autonomous ICD completion is aided with an accurate prediction of the flow behavior through the device. This paper describes flow testing and field performance of a fluidic diode autonomous ICD optimized for the production of very heavy oils with a viscosity above 150 centipoise (cp), while restricting water and gas production. The test results of the autonomous ICD demonstrate that the fluidic diode can produce more oil while restricting water. In fact, heavy oil can flow at a higher rate with less pressure drop than water. Flow performance of this device has been characterized by measuring the pressure drop versus the flow rate at differing viscosities, confirming that the autonomous ICD effectively restricts undesired fluids, while enhancing the production of oil. Numerical simulations demonstrate an improvement of water reduction by more than 50% compared to standalone screen completions. This technology has been used to promote oil production and restrict water influx in fields where the oil viscosity is greater than 700 cp. This paper also demonstrates the appropriate design philosophy when determining the suitable application of the technology to help maximize oil recovery and minimize water production. Fluid flow performance is what truly distinguishes the autonomous ICD from other devices. This fluidic diode autonomous ICD is a robust, reliable solution with no moving parts, nor the requirement of intervention of any kind. Its predictable flow performance has been proven through testing, modeling, and field application.

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.