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Guided wave transmission for downhole applications

IP.com Disclosure Number: IPCOM000238256D
Publication Date: 2014-Aug-12
Document File: 4 page(s) / 490K

Publishing Venue

The IP.com Prior Art Database

Abstract

This disclosure proposes a novel way to generate strong down-hole signal through waveguide wireless transfer for magnetic ranging application. The wireless transfer is achieved by transmitting the signal through either the unique structure of the target borehole with tubing as waveguide or a custom-made waveguide integrated outside the casing. Minimal loss is achieved with long distance signal transfer from surface to down-hole without access of the target well. The magnetic ranging system with wireless transfer is simple and reliable without extended wire routing or grounding. It can be used in magnetic ranging applications like SAGD, well intersection and anti-collision applications.

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Guided wave transmission for downhole applications

Abstract- This disclosure proposes a novel way to generate strong down-hole signal through waveguide wireless transfer for magnetic ranging application. The wireless transfer is achieved by transmitting the signal through either the unique structure of the target borehole with tubing as waveguide or a custom-made waveguide integrated outside the casing. Minimal loss is achieved with long distance signal transfer from surface to down- hole without access of the target well. The magnetic ranging system with wireless transfer is simple and reliable without extended wire routing or grounding. It can be used in magnetic ranging applications like SAGD, well intersection and anti- collision applications.

  Index Terms-Waveguide wireless transfer, Magnetic ranging, SAGD.


1. INTRODUCTION

Magnetic ranging tools are widely used in many down-hole applications like SAGD, well interception and well avoidance. It helps to accurately control the relative distance and direction between drilling well and target well with close proximity.

Different approaches have been proposed in previous years to generate magnetic signal as the ranging source. Prior arts (Kuckes, 1998) (Kuckes, 1996)employs a solenoid secured to a wire-line. It is lowered into the target well through the well casing if the target wellhead is accessible. The upper end of wire-line is connected to a well logging vehicle by means of which the solenoid can be raised and lowered within casing to specified depths that are leveled to the magnetometers located in the relief well to make the measurement. The advantage of this excitation approach is that the signal strength is high and even a modest current in the range of a few amps can generate a magnetic field which is readily measured by the sensors 150 feet or more away. The drawback of this approach is that it needs to access target well borehole. In addition a movable wire-line is needed and periodical adjustment of solenoid level is needed. This results in extra equipment and operational cost.

Prior art (Kuckes, 1988) (Kuckes, 1993) injects current from wellhead to produce static or time- varying current flow along the target casing. The magnetic or electric field generated by this current flow is detected by the sensor in the drilling string. Distance between two wells is determined from the measured fields. The limitation of this approach is the weak down-hole signal for deep wells and poor signal to noise ratio at the sensor. Accurate guidance may not achievable for deep wells applications.

Prior arts (Kuckes, 2012) (Kuckes, 2012) inject current into the earth in the near proximity of the target well casing by an electrode located at the relief wellbore. Another electrode is placed at the earth surface as the grounding point. The current is finding the shortest path to return and will goes though the target casing. The characteristic magnetic field generated by the target casing...