Abstract

Intelligent drill string components capable of transmitting data at rates up to 2-megabits per second have been developed and successfully tested in commercial drilling applications.

This paper details the lessons learned during intelligent drill string field trials, with focus on the overall network performance during drilling operations, physical handling ease and integration of existing down-hole measurement tools into the network.

This is the first publication of information from such field trials, and the first discussion of down-hole tool data transmission through the intelligent drill string network.

The paper includes discussion regarding the potential impact of intelligent drill string technology on the drilling and completion process.

This new technology can improve well productivity, reduce drilling time/costs and enhance well control safety. The paper addresses these issues and provides a forward-looking view regarding large-scale introduction of the system and the anticipated time-line for commercial availability.

The intelligent drill string system incorporates a high-speed data cable protected in a high-pressure conduit that runs the length of each joint. The cable terminates at inductive coils that are installed in grooves machined in the secondary torque shoulders of double-shoulder connections at each end of the joints.

The system's design supports high-speed, high-volume, bi-directional data transmission to and from hundreds of discrete measurement nodes. As a result the system offers an opportunity to capture critical data along the full length of a drill string, not just at the bit, in addition to supporting the use of high-resolution LWD tools and providing instantaneous control of down-hole mechanical devices. The system offers robust, reliable operation and is virtually transparent to standard rig procedures.

Introduction

Mud pulse telemetry is the current industry standard for transmission of data from MWD and LWD tools to surface and typically functions at 3 to 6 bits/sec, rising to 12 bits/sec under ideal conditions. These relatively low data rates force multiple sensors to compete for bandwidth, limiting data density and demanding complex downhole processing systems in order to achieve modest real-time measurement resolution.

Mud pulse telemetry presents several other significant barriers to data flow during the drilling process:

1. A limited capability to receive commands from surface often results in significant non-productive time when changes in down-hole tool functionality are required.

2. The requirement that all sensors be in close proximity to the mud pulse tool prevents distributed measurements along the drill string.

3. The inability to transmit data when circulation stops can leave the driller blind during well-control situations.

Seven years of engineering and development, funded in part by the U.S. Department of Energy, has produced an intelligent drill string network capable of transmitting data at rates up to 2 Megabits/sec.

This system makes it possible to obtain large volumes of data from existing MWD/LWD tools instantaneously - greatly expanding the quantity and quality of information available in ‘real-time’. In addition, the system design means data can be transmitted both upwards and downwards, from hundreds of distributed measurement devices, regardless of circulation conditions. Each device can be defined as a node with a unique address and can gather or simply relay data from a previous node onto the next.

Network protocol software and hardware control the flow of information between devices. Since every node is uniquely identifiable, the location where events occur along the length of the well can be determined.

The system's bi-directional communication architecture means not only is high-speed transmission of downhole data to the surface possible, but also commands from the surface to devices downhole or even between downhole devices can be sent, received and acted on.