New technologies such as maximum reservoir contact wells and multi-lateral wells promise to improve oil recovery and make marginal accumulations economic through controlled commingling. The key to successful exploitation of these technologies is the ability to monitor and control the movement of fluids into and out of each reservoir zone. Intelligent well technology provides the capability to manage the flow of fluids in the well bore, without intervention, enabling complex well architecture to enhance recovery and tap marginal reserves.

The North Sea sector has long been a leader in the application of intelligent well technology. Worldwide there have been over 200 intelligent well installations by all suppliers since the first WellDynamics’ SCRAMS‚ installation in 1997 for Saga in the North Sea. To date, WellDynamics’ have installed over 120 SmartWell‚ completions, of which 33 have been in the North Sea.

Adding Value with Intelligent Wells Intelligent wells have many applications. Principal of these is the ability to actively manage the reservoir recovery process. This is especially important for secondary water floods or tertiary EOR projects. Intelligent wells can be used to control the distribution of water or gas injection in a well between layers, between compartments, or between reservoirs. They can be used to restrict or exclude production of unwanted effluents (water and/or gas) from different zones in a production well. As a result, the operator can manage where he injects water or extracts oil to mobilize unswept reserves. This is particularly important for wells with complex architecture – extended reach, long horizontal or multilateral wells – and for reservoirs characterised by high degrees of anisotropy, heterogeneity or compartmentalization.

In 2001, a study commissioned by the Department of Trade and Industry in the United Kingdom to identify future opportunity for reserve development in the North Sea found that many reserve accumulations have been discovered which are too small or too marginal to be developed on their own. However, many of these small reserves are stacked or in close proximity to others. Sequential exploitation does not produce the oil fast enough or in great enough volumes to be economic with conventional development methods.

HVS valve flow trim section

The solution to this problem is to commingle the uneconomic reserves. Intelligent well technology addresses the reservoir management and regulatory concerns with controlled commingling by providing individual zone control, the ability to prevent cross flow, and the ability to allocate flow to each individual reservoir.

Finally, with down-hole sensing and accurate data acquisition, the operator can achieve a better understanding of the reservoir and recovery process, and can use this knowledge to make better and more informed operational decisions faster. We call this concise reservoir management. Interpretation and modelling, option analysis, workflow and decision processes are all part of the chain of real-time reservoir management. The dividends are better use of asset infrastructure, reduced effluent production, accelerated production, improved hydrocarbon recovery and better selection of infill well locations and numbers of wells to efficiently develop an asset.

Intelligent Well Technology
Intelligent well functionality may be classified by flow control options and sensing options. There are several flow control capabilities, actuation methods and choke trim designs from which to choose. Downhole flow control valves may be binary (on-off), choking with limited discrete settings, or infinitely variable choking. Actuation methods may be hydraulic, electric, or the hybrid electrohydraulic. For infinitely variable choking or multiple discrete choking, the control trim profile can be standardized (typically equal percentage or linear) or can be custom designed for the reservoir application. The selection of the right flow control option is critical, as it may have an impact on the number of zones/intervals that can be realistically controlled in one well, and may affect the overall reliability of the integrated system.

The most common down-hole sensor technology in use are electronic pressure/temperature gauges. Downhole flow meters combine gauges with a differential pressure flow measurement element, such as a venturi. Optical fibre distributed temperature sensors are now a mature technology, and new technologies such as optical fibre pressure sensors and optical fibre flow meters are available.

WellDynamics and SmartWell® Technology
Clients are currently focused on two primary concerns with intelligent well technology – reliability and cost. New technology and improved designs are constantly evolving, particularly focussing on improved reliability and lower costs.

With its market leading installation base, extensive reliability engineering and unparalleled experience, WellDynamics has led the intelligent well industry in the development of integrated systems-based reliability measures and information. Anticipating growth for intelligent completion systems in some of the world’s most challenging environments, WellDynamics has invested several million dollars in a state-of-the-art test facility, opened in June 2001 at the Spring, Texas complex.

Intelligent well system costs have been steadily declining in line with economies of scale and improved designs for manufacturing. WellDynamics delivers a suite of tools in a broad spectrum of functionality and sizes, permitting the operator to select the "right level of Smartness for the right asset at the right time."

Flow Control Valve, Digital Hydraulics™ and Accu-Pulse™
To meet the demand for highly reliable, lower cost flow control options, WellDynamics has added several hydraulic-based products to its flagship integrated electrohydraulic line, SCRAMS, which already enjoys widespread application in the North Sea.

Digital hydrolics decoder

The HV line of flow control valves are hydraulically actuated, balanced, remotely operated interval control valves (ICV) which offer metal-to-metal closing seals, rugged tungsten-carbide flow trims, high differential pressure capability, and customisable flow trim designs. The HVO-ICV is an open/close valve while the HVCICV offers a 10-position choking element, including a version with flow trim designed for gas-lift applications. The HV line of valves is available in a range of sizes from 2-7/8 to 5.5 inches, and is suitable for both production and injection applications.

HVC Valve Flow Trim Section
WellDynamics’ award-winning Digital Hydraulics™ system enables multiple hydraulic devices (typically ICVs) to be controlled from fewer hydraulic control lines, providing direct down-hole control without the requirement for a large number of tubing hanger penetrations. With the Digital Hydraulics system, three control lines can control up to six downhole devices. Each HV-ICV is coupled directly to a Digital Hydraulics decoder that is in turn connected to the surface via the hydraulic control lines. Each decoder has a unique address that is activated from surface by the sequence in which the control lines are pressurised. Once a decoder is activated, hydraulic communi-cation is established with the decoder’s corresponding ICV, allowing full, independent control. The operation of the Digital Hydraulics decoder is not pressure dependent, and as such, the application of this technology is not depth dependent.

Digital Hydraulics Decoder
Discrete, incremental positioning of the HVC-ICV, either in direct hydraulics or Digital Hydraulics configurations, can be achieved using WellDynamics proprietary Accu-Pulse™ down-hole control system. Accu-Pulse is a hydraulic control device that provides incremental positioning of the ICV choke by dispensing a predetermined amount of control fluid to one side of the ICV actuating piston. Like Digital Hydraulics, Accu-Pulse is an all-hydraulic system that does not rely on J-slots or gas or mechanical return springs for positioning of the ICV.

Accu-Pulse Module
The price of oil recently exceeded the $40/bbl mark to reach the highest prices in the last 20 years. While oil and gas companies are finding it difficult to replace produced oil reserves, there is constant pressure from the investment community to maximize short-term profitability to boost equity value. Production from the mature major basins is declining, and the areas where companies are finding significant new reserves are evermore challenging. SmartWell completion technology, is reliably delivering the promise of improved recovery with lower capital investment.

Accu-Pulse module