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Identification of depth of downhole surface by reflecting waves

IP.com Disclosure Number: IPCOM000246212D
Publication Date: 2016-May-17
Document File: 3 page(s) / 139K

Publishing Venue

The IP.com Prior Art Database

Abstract

The idea is to send a wave down the hole from surface – either hydraulically through the annulus mud column, or through the string mechanically. This wave would travel downhole with known speed, will be reflected at a reflector, and travel back. The travel time is measured and with travel speed the reflection depth calculated. For a hydraulic pressure pulse down the annulus, this reflector could be the top of a gas bubble, of a cement column, or of a fish. (For a torsional or axial pulse along the string, the reflector could be a stuck point or the broken-off end of a twist-off.)

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Identification of depth of downhole surface by reflecting waves

Key Words:
Wave, travel time, travel speed, Oil&Gas, Drilling, Downhole, Drilling Engineering, Reflection, depth, depth identification, fish, cement plug, top of gas, top of pill, mud, drillstring,

Abstract:

The idea is to send a wave down the hole from surface - either hydraulically through the annulus mud column, or through the string mechanically.

This wave would travel downhole with known speed, will be reflected at a reflector, and travel back. The travel time is measured and with travel speed the reflection depth calculated.

For a hydraulic pressure pulse down the annulus, this reflector could be the top of a gas bubble, of a cement column, or of a fish.

(For a torsional or axial pulse along the string, the reflector could be a stuck point or the broken-off end of a twist-off.)

The novelty is to create a pressure pulse down the annulus, measure its return travel time on surface, and calculate the position where it was reflected.

The benefits to detect the (sometime changing) depth may contain for


 Cement: calculate cross sections, induce hole quality and cement quality (especially if there are thief zones near the casing shoe).


 Kick: identify current height of the gas bubble.


 Twist-off: confirm twist off before POOH; faster mobilization of (correct) fishing equipment


 Stuck pipe: confirm stuck depth. Qualify if entire cross section or just part of it is packed (e.g. keyhole vs swelling shale). Mitigate accordingly with greater confidence.

When applying the same concept from the bit (rather than surface) downwards, it would give more confidence in distance bit to bottom of hole. This would allow for better bit landing procedures, especially for floater rigs in rough seas with wired pipe.


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What problem does it solve?

There are various problems that can be solved - basically any downhole major cross section change or mud interface in the annulus may be depth-measured and possibly characterized for completeness or cleanliness.


 For cementing: this serves as a confirmation (or not) for a successful quality cement job


 For kicks: This serves as a confirmation that a kick is happening and the current depth and speed of the gas, quantifying the time left till it reaches surface.


 For stuck pipe: Confirmation of depth and possibly characterization of stuck pipe mechanism

Concept in detail:

The main idea is to create pressure pulses on surface in the annulus. This may be easiest in an MPD (managed pressure drilling) application where the annulus is restricted and opening and closing the annulus creates pressure pulses during circulation.

These pressure pulses are traveling downhole with known travel speed, calibrated to...