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Methods for inverting electromagnetic logging measurements

Through the two-step inversion method and point dipole model, the problem of accurate measurement of multi-layer formation properties and drilling effects in downhole electromagnetic logging is solved, and high-accuracy calculation and error elimination of multi-layer formation properties are achieved, improving improve the reliability of well logging data.

Active Publication Date: 2018-07-17
SCHLUMBERGER TECH LTD BV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

An electromagnetic logging-while-drilling tool acquires electromagnetic voltage measurements as it rotates in a subterranean borehole

Method used

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  • Methods for inverting electromagnetic logging measurements
  • Methods for inverting electromagnetic logging measurements
  • Methods for inverting electromagnetic logging measurements

Examples

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Embodiment Construction

[0025] figure 1 An exemplary drilling rig 10 suitable for employing various method embodiments disclosed herein is depicted. Semi-submersible rig 12 is positioned above an oil or gas formation (not shown) disposed below seafloor 16 . Subsea pipeline 18 extends from deck 20 of platform 12 to wellhead 22 . The platform may include a derrick and hoisting equipment for raising and lowering a drill string 30 which, as shown, extends into the borehole 40 and includes deployment at the lower end of a bottom hole assembly (BHA). The bottom hole assembly further includes an electromagnetic measurement tool 50 configured to perform directional electromagnetic logging measurements. As described in more detail below, the electromagnetic survey tool 50 may include a multi-axis antenna deployed on a logging-while-drilling tool body.

[0026] will understand that in figure 1 The deployments described above are examples only. Drill string 30 may include substantially any suitable downhol...

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Abstract

A two-step inversion method for computing multi-layer subterranean formation properties includes processing gain compensated electromagnetic measurement quantities using a first inversion to compute acorresponding set of borehole corrected gain compensated measurement quantities. The first inversion includes a mathematical model of the tool and the borehole in a uniform, anisotropic formation. The set of borehole corrected gain compensated measurement quantities are then processed using a second inversion to compute multi-layer anisotropic formation properties. The second inversion includes a1D inversion employing a point dipole model and a multi-layer formation model.

Description

[0001] Cross References to Related Applications [0002] This application claims priority to US Provisional Application 62 / 254,541, filed November 12, 2015, which is incorporated by reference in its entirety. technical field [0003] The disclosed embodiments relate generally to downhole electromagnetic logging methods and, more particularly, to methods for inverting electromagnetic logging measurements using layered formation models. Background technique [0004] The use of electromagnetic measurements in prior art downhole applications (eg, logging while drilling) is well known. Such techniques may be utilized to determine formation resistivity, which, along with formation porosity measurements, is often used to indicate the presence of hydrocarbons in the formation. [0005] To accurately measure formation properties, such as vertical and horizontal formation resistivity, electromagnetic logging measurements may need to be corrected for borehole effects. Such effects ar...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): E21B47/00G01V3/18G01V3/38
CPCG01V3/18G01V3/26G01V3/28G01V3/38
Inventor P.T.吴
Owner SCHLUMBERGER TECH LTD BV
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