Knowledge management, the great enabler of great achievements, has as its cornerstone global connectivity. As connectivity extends itself into the downhole world, it must pass through several narrow apertures. To prevent these from becoming insurmountable bottlenecks requires an internationally accepted standard. Because of the huge scale of capital investments, operating costs, and profit potential of subsea oil and gas fields, early emphasis has been given to the evolution of subsea production systems.

The critical elements of a subsea field include seabed trees and safety systems, downhole

Object-link-embedded process control (OPC) clients at the production operations facility link through an OPC server to the subsea wellhead downhole controller cards (IWIC and/or IFIC) using the operator’s subsea communication and control network. Multiple nodes can be operated and controlled through a single power/communications cable. (Image courtesy of Schlumberger)
monitoring and control systems, flow assurance equipment, and subsea processing systems. These elements come from a wide variety of vendors and subcontractors. All elements must be linked by field communications networks and all must be able to seamlessly communicate with the field production office and, in many cases, with company headquarters. Absent a standard interface system, this could be a recipe for chaos and a receptacle for costs.

Reducing complexity and cost
Intelligent Well Interface Standardization (IWIS) was created by a joint industry panel established in 1995 and consists of leading deep sea operators and service/ supply companies. Its objective is to reduce complexity and costs of implementing intelligent subsea well systems. In a comprehensive standard published as ISO-13628-6 in May 2006, IWIS addressed such considerations as physical configurations, electrical power, communications, testing and qualification process for subsea interface cards required to interface intelligent wells to subsea control systems.

The standard aims to facilitate deployment of subsea intelligent completions by providing access to data from downhole tools and monitoring systems, significantly reducing customization requirements for every project and enabling the ability to deploy future downhole measurement systems without having to modify the infrastructure. It also enables subsea operators to access data made available by the downhole measurement and control systems using commercially available software packages and without having to “teach” the subsea infrastructure how to interface with them.

Before IWIS, there was little flexibility between systems that should be complementary. There were a large number of different interface combinations, and incompatibility existed in such seemingly simple things as card size, number of connecting pins and their alignment. This caused expensive duplication of system functions, leading to logistical limitations and reliability problems. Because each new component had to be thoroughly systems-tested before it could be accepted, lead times were excessive. Even when system components were somehow plugged together, system performance was compromised. The holy grail called “plug ‘n’ play” was a distant mirage.

IWIS represents a complete game-changing development. It will enable rapid deployment of new technology by removing the huge barrier of compatibility with existing systems and with the field communication and control infrastructure. For new technology developers, making something compliant is much easier than inventing an entirely new system, and it is a much easier “sell” if you don’t have to first “unsell” the legacy system. If an operator wants to design a production infrastructure using a mixture of downhole and surface instrumentation with telemetry and communications from different vendors, IWIS enables it. If someone has made a big investment in a legacy system but now wants to add new technology, IWIS enables it. Now, instead of having a huge specification document for each project, all a vendor has to do is make a new product comply with the IWIS standard and it will interface seamlessly when it is implemented.

Compliance is easy
Usually, making an element or subassembly IWIS-compliant involves only development of one or two system interface cards. These fit into standardized slots in an environmentally sealed retrievable subsea module. For example, recently Schlumberger announced the commercialization of the company’s 100% IWIS-compliant subsea interface card for enabling WellWatcher downhole monitoring and WellNet communications systems. The former can power up to four gauges on the same cable, providing the subsea network with both raw data and ready-to-use engineering values; the latter supports up to 64 communication systems nodes using high-speed telemetry capable of operating electric flow control valves through a single electric line. Both systems offer full redundancy and self-verification features to ensure reliability and signal integrity. The IWIS-compliant systems complement another key IWIS objective. By operating on a single wire, they minimize the number of tubing hanger penetrations.

What’s in it for me?
Experience has proved that having access to critical production knowledge pays off during the life of the well or reservoir. Often the cost of deep sea intervention services has forced acceptance of diminished performance and shortened lifetimes for subsea wells. In the US alone, this lost production from subsea wells is estimated to cost the industry $10 billion annually. With the real-time availability of critical reservoir and production data, production can be optimized and economic lifetimes extended. Costly interventions can be avoided unless absolutely necessary.

A case in point
In the Asia Pacific region, the service company will deploy advanced permanent reservoir monitoring systems in several deepwater dual-completion type wells. Each well has multiple commingled reservoirs, which pose many challenges for the operator during the drilling, completion, tie-back and production phases. Maintaining real-time knowledge throughout these critical stages, which will span a period of more than 20 years, required a new intelligent completion technique.

A multifaceted approach in the lower sand face and upper completions was undertaken to provide true pore-to-desktop connectivity. The company’s permanent monitoring sensors are embedded within the lower completion in the surrounding gravel pack by design. The system’s IWIS-compliant WellNet subsea interface card — IWIC — allows well data to flow seamlessly to the operator’s production operations facility. The downhole telemetry offers the latest advances in downhole communication technology with full duplex capability. This use of IWIS-compliant technology ensures that the system will be fully compatible with the existing field infrastructure and any future subsea systems that may be installed. Access to the well will be through a single wellhead port, with both power and data communications multiplexed on a single conductor.

An RTAC (Real-Time Acquisition and Control) system will be provided in the master control room to communicate with the subsea interface cards.

Functioning as an OPC-client, it has full access to the subsea interface cards and communicates with the downhole monitoring and control hardware. Upon commissioning, a data stream will enable full visibility of reservoir and production parameters illuminated in real time. It also provides the required functionality for diagnosis and troubleshooting in real time without the need for intervention systems. The real-time acquisition and control system can be used to download firmware into the subsea interface cards, and it can download firmware into the downhole tools and reconfigure them as needed over the life of the well.

The system architecture can expand to handle additional wells that may be tied back to the production system. It is scalable and allows for incorporation of additional sea bed measurements like multiphase flow meters if required.