Downhole power generation and communications apparatus and method

#This application claims the benefits of priority from: i) Application Number 0320804.8, entitled “DOWNHOLE POWER GENERATION AND COMMUNICATIONS APPARATUS AND METHOD,” filed in the United Kingdom on Sep. 5, 2003; and ii) Application Number PCT/GB2004/003753, entitled “DOWNHOLE POWER GENERATION AND COMMUNICATIONS APPARATUS AND METHOD,” filed under the PCT on Sep. 2, 2004; All of which are commonly assigned to assignee of the present invention and hereby incorporated by reference in their entirety.

#The present invention generally relates to communications with the long-term placement of downhole completions equipment. More particularly, the present invention relates to an apparatus and method to wirelessly communicate with downhole completions equipment. More particularly still, the present invention relates to methods and apparatuses to wirelessly communicate with and generate power for downhole completions equipment, particularly those permanently installed in the well.

#Because of the variety of sensor and measurement devices used in oilfield drilling and production operations, various communication systems and schemes are often necessary. One form of communications that continually challenges the industry relates to the communication between surface and downhole equipment. Particularly, it is often necessary to retrieve data from downhole equipment and sensors for processing and decision-making at the surface. Operations such as drilling, perforating, fracturing, drill stem or well testing, and hydrocarbon production require measurements of downhole pressures and temperatures at various depths of investigation. Furthermore, communication from the surface to downhole sensors is often desired as some sensors or downhole tools accept commands from the surface to direct their operation.

#FIG. 1 is a schematic representation of a downhole communications system in accordance with preferred embodiments of the present invention.

#FIG. 2 is a schematic representation of a voltage rectifier circuit in accordance with preferred embodiments of the present invention.

#FIG. 3 is a schematic representation of a mechanical to electrical energy converter in accordance with preferred embodiments of the present invention.

#Referring initially to FIG. 1, a downhole communications system 100 is shown schematically. Downhole communications system 100 preferably includes a surface unit 102 and a downhole communications package 104. Surface unit 102 preferably includes a pressure wave generator 106, a signal processing unit 108, and pressure transducers 110, 112. Pressure wave generator 106 is shown as a piston-type pressure generator that includes a motor driven piston producing a reciprocal movement within a cylinder but may be of any type known in the art. Surface unit transmits, receives, and analyzes pressure wave signals to and from communications package 104.

#Communications package 104 is shown located downhole in an annulus 114 between strings of production tubing 116 and casing 118. Ideally, packers 120, 122 isolate sections of strings 116, 118 so that distinct measurements in a zone of investigation 124 can be taken by downhole sensor package 126 (downhole sensor). Downhole sensor package 126 can be of any type known to one skilled in the field of hydrocarbon production, but typically will include pressure and temperature sensing devices that are capable of operating with minimal power input. Downhole sensor package 126 is preferably connected to a downhole control module 128 where the data therefrom can be accumulated, converted to digital bit streams, and transmitted to surface unit 102 for analysis. Furthermore, additional sensors 130 from production tubing bore 132 or other zones of investigation may also tie back to downhole control module 128 for transmission to surface unit 102.

#Ideally, control module 128 is constructed as a low power-consuming computational device capable of regulating numerous downhole processes. While control module 128 may be constructed as several individual components including, but not limited to, data processing, valve actuation, data transmission, and electrical regulatory components connected together by a communication protocols, module 128 is shown in Figure schematically as a single component for simplicity.