The emergence, development and first implementation of RADIO FREQUENCY IDENTIFICATION (RFID) technology used to actuate self powered downhole tools are discussed. A case history is also presented.
Daily contact with RFID technology is all but inescapable. Typical uses include toll road monitoring, retail inventory control, banking and tracking of livestock and pets.
RFID as an enabling technology was recognized for its potential to replace and/or complement existing methods of downhole communication, such as wired coiled tubing and downhole tubulars, ball drop operations, fibre optics, i-wire and EM telemetry. Additionally, the prospect of actuating self-powered downhole tools created an attractive and potentially highly rewarding improvement in operating costs at the wellhead through a reduction in third party wellhead asset value, less time in the hole, reduced number of trips and multi functional capabilities.
RFID in this application has two inherent parts.
The TAG, which is encoded with the appropriate command data.
The READER which is housed in the downhole tool.
The encoded tag is released into the well at surface from where wellbore flow of fluids, gas or condensate transports it down the well tubulars until it passes through the reader antenna. The high power antenna within the downhole tool energises the passive tag then reads and stores the tag data. Typically the tag data will consist of a command to actuate the tool by means of a self contained hydraulic pump, electric motor and battery pack. Operations such as opening and closing valves, indexing and release mechanisms and a multiple of other functions can be implemented. Multiple tools can be run at the same time without compromising the tool internal diameter. Each tool has a unique address therefore tags can be coded with data that picks out an individual tool to be actuated. Time delays and repeat sequence commands are all possible.
The case history presented in this paper describes the use of this technology to open and close a drilling circulation sub.
The tool was run by a North Sea operator as part of a drilling operation. The circulation sub was opened at a depth of 10,100 ft. by flowing an "Open" command tag from the surface. After circulating, the tool was closed by flowing a "Close" command tag.