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Downhole Position Identification by Downhole Triangulation

IP.com Disclosure Number: IPCOM000246583D
Publication Date: 2016-Jun-20
Document File: 8 page(s) / 330K

Publishing Venue

The IP.com Prior Art Database

Abstract

Central Idea: in several nearby offset wells, completions equipment such as special ESPs are deployed, emitting simultaneously EM pings at more than one frequency. The receiver in the BHA receives the signals, measures differential arrival time, and triangulates its own position based on known positions of the sources. At frequent pings, the borehole survey frequency is "continuous".

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Downhole position identification by downhole triangulation

Abstract of invention:

Central Idea: in several nearby offset wells, completions equipment such as special ESPs are deployed, emitting simultaneously EM pings at more than one frequency. The receiver in the BHA receives the signals, measures differential arrival time, and triangulates its own position based on known positions of the sources. At frequent pings, the borehole survey frequency is "continuous".

Novel Features and Benefits:

The novelty is that rather than doing dead reckoning, the position (rather than direction) is triangulated downhole.

What problem does it solve?

- No positional uncertainty growth along MD - potential to be much more accurate, especially in long wells

- 3D-location is measured and known downhole at all times - no need to assemble it on surface with additional MD data. It may be used to do improved Geosteering.


- No direct need for telemetry
- No stopping for surveying, no vibration influence
- No magnetic influence
- Continuous surveying
- No need for non-mag steel in BHA for directional measurements any more.

Invention in detail:

In mature fields, typically there is


 A great need for improved wellbore positioning, due to collision avoidance needs


 lots of magnetic interference at beginning of sidetracks and near well crossings - exactly where positioning accuracy needs are high


 lots of nearby wellbores - producers, injectors, plugged-and-abandoned

The idea is to use multiple EM (or, possibly acoustic) transmitters in offset wells (or higher up in the same well) at well-known spacial positions and at well-defined relative times to ping, with the receiver in the (drilling) BHA. The transmitters may be deployed with ESPs - as they are often plentiful, roughly in the right location, and already feature a cable for power supply. On surface, a command is given to the different transmitters that initiate each to ping - where the absolute time is not of importance, but just the relative timing of the pings. No need for synchronized, accurate clocks. The processor in the BHA has the position and signal characteristics of the different transmitters downloaded prior to deployment. From the travel time, the computer in the BHA


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calculates the distance to each transmitter. With signals from multiple transmitters, the relative position to the transmitters is determined.

Alternate construction methods:

1) There may be more than one receiver along the drilling BHA to measure the shape and position of the entire BHA

2) For new fields: Instead of using completions equipment in offset wells for transmitters, deploy transmitters in the already drilled section in the current well (e.g. inside casing). One challenge is the simultaneous triggering of the ping for the different transmitters. This may be solved by transmitter 1 triggering transmitter 2 activation and so on, with the MD difference of the two known.

a. Instead of deployment of trans...