Digital core workflow method using digital core image

Abstract

A method for registration and correction of downhole core depth information using digital core images. Digital core images are employed during depth registration, with top and base depths for a selected interval being determined by field data and a digital ruler which calculates an actual interval length based on the digital core image. Correction of the top and base depths is enabled by side-by-side display of the digital core image interval and corresponding well logging data, which displayed information can be manipulated by a user to provide more accurate depth information. The method further allows for shale volume calculations and facies interpretation, again employing the digital core images.

Description

FIELD OF THE INVENTION [0001] The present invention relates to methods for determining formation depths, and more particularly to core logging methods. BACKGROUND OF THE INVENTION [0002] Although relatively expensive, coring—the taking of subsurface rock samples with specialized drilling tools—is one of the oldest methods of subsurface formation evaluation and the only method (other than cuttings analysis) for providing rock samples for laboratory analysis. Coring is used to provide geologists and other earth scientists with physical rock samples that can provide much-needed information on a direct rather than indirect basis. [0003] A core bit is used to cut a generally cylindrical section of rock that is contained within a coring tube, which section within the tube is then brought to surface (any expected portion of the core that does not make it back to surface is considered to be “lost core”). The core tube is marked with a well name, core number, and subsurface interval depths a...

AI Technical Summary

Benefits of technology

[0037] i. allowing for correction of the first depth and the second depth.

[0090] In the end, the present invention can produce highly accurate depth determinations, integrating depth registration / correction with sample picking, image annotation, VSH (shale volume) calculation and picking facies intervals directly from digital core images, streamlining the entire core workflow.

Problems solved by technology

During drilling, core depths are recorded by workers on a drilling rig, but very often they are not accurate (off-depth), and the geologist is faced with the task of attempting to determine depth information based on rock that has already been brought to surface.

The manual, hard-coded labelling is a very time-consuming process and prone to errors; it also makes any updating of labels extremely difficult, especially when the geologist changes a depth.

As is abundantly clear from the foregoing, there are numerous disadvantages to the traditional physical core workflow: 1) Several people are necessarily involved.

The more people that are involved, the harder it is to co-ordinate and the more opportunities there are for mistakes.

There are more inherent errors as well.

2) The traditional workflow is time-consuming (as can be seen in FIG. 2).

The process is slow and prone to errors; in addition, any change in the depth of a depth marker requires repetition of the above steps.

The labelling process is time-consuming and prone to errors, and the resultant labelling (now part of the images) is hard-coded and makes it extremely difficult to make any required updates and changes.

6) Due to the time-consuming nature of the traditional workflow, sample selection and sample depth calculation are normally carried out by a lab technician with sampling guidelines provided by a geologist.

As a result, sample selection is not totally controlled by the geologist, and very often more samples are taken than is needed.

Images