When downhole tools that collect data were created, they stored the data in memory on the tool itself. The data were downloaded when the tool was next pulled from the hole. Improvements in technology offer new options for real-time transfer of data from downhole tools, with the potential for identifying potential problems sooner. >> Oil & Gas Engineering Books <<
Communication with downhole tools while drilling is currently achieved with either mud-pulse telemetry or electromagnetic-based systems. The maximum data transmission rate (correlated with bandwidth) of these systems is about 10 bits per second. As a result, much of the information from measurement while drilling (MWD) and logging while drilling (LWD) must be processed and stored in computer memory associated with the downhole instrumentation near the drill bit. The term “real-time monitoring” can be applied in only a very limited sense with current technology.
The potential for true real-time monitoring has increased significantly with the initiation of the commercialization phase of a Dept. of Energy (DOE) technology development contract with Novatek, Inc. Novatek and its partner, Grant Prideco, have begun commercial construction of Intellipipe®. Intellipipe represents a novel and robust means of transmitting data up drillpipe at a transmission rate of 1 million bits per second. Key to the success of this technology was development of a high-efficiency coupling that enabled successful transmission of data across many tool joints without the need for amplification over lengths exceeding 1,000 ft. Another key feature of the system is that it will allow the drillpipe to act as a local area network within which many different tools or systems located anywhere within the drillstring can be individually addressed and/or turned on and off. Fig. 1 is a concept drawing that shows the basic components of the proposed real-time monitoring and control system. Fig. 2 details the components of the electromagnetic coupling across the tool joint. The recessed coil in the pin connection comes in very close, controlled proximity with the coil in the base of the box connection during makeup. The design results in a strong connection and forms the basis of a robust, reliable, efficient electromagnetic coupling for transfer of data across the connection.
Fig. 1—Intellipipe local area network concept (1 million bits per second).
Fig. 2—Intellipipe coupling detail.