Method for analyzing drill cuttings using nuclear magnetic resonance techniques

Abstract

A method for evaluating permeability of Earth formations includes determining a transverse nuclear magnetic relaxation spectrum by performing a nuclear magnetic resonance experiment directly on drill cuttings of the Earth formation removed from a wellbore, and estimating permeability from the transverse nuclear magnetic relaxation spectrum.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] Not applicable. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT [0002] Not applicable. BACKGROUND OF INVENTION [0003] 1. Field of the Invention [0004] The invention relates generally to the field of evaluation of petrophysical properties of Earth formations. More specifically, the invention relates to methods for evaluating petrophysical properties of Earth formations using samples of drill cuttings and using nuclear magnetic resonance (NMR) measurement and analysis methods. [0005] 2. Background Art [0006] Faster drilling and higher drilling cost (especially offshore) dictate reducing cost and decreasing the time required for well evaluation. Simultaneously, it is necessary to ensure the reliability of the results of such evaluation. This is especially important for Earth formation reservoirs that include complicated geology and that may involve long exploitation time, because the in-situ oil viscosity can be different i...

AI Technical Summary

Benefits of technology

"The patent describes a way to evaluate the permeability of underground formations using a special technique called nuclear magnetic resonance. This method involves taking drill cuttings from the formation and measuring the relaxation time of the nuclear magnetic signals. By analyzing this data, researchers can estimate the permeability of the formation. This technique can provide a more accurate and reliable way to evaluate the quality of oil and gas reservoirs, which can help improve the process of drilling oil wells."

Problems solved by technology

The above methods known in the art have a number of limitations.

Formation evaluation while drilling technologies are relatively expensive and their application requires a high degree of well stability.

Interpretation of the results frequently includes operational noise from the drilling process.

First, it is difficult to use only one type of measurement to determine the generally required petrophysical parameters, these parameters including fractional volume of pore space in a reservoir formation (porosity), and permeability, that is, the quantitative determination of filtration capacity properties (FCP) require a set of different tools (Santarelli, 1998; Marsala et al., 1977; Nes et al, 1998).

It has also proven to take too long to provide quantitative on-line information during drilling on well site.

However, advanced mud logging at the well site is labor intensive, and thus expensive, and can be applied generally to drill cuttings having particle sizes of more than 3 mm.

The difficulties of measurements using high field NMR spectrometers, namely the high radio frequency, and difficulty of handling the large size of high field instruments discouraged wider use of this technology at the well site.

However, the processes used on coarse cuttings have not proven effective for determining petrophysical parameters on fine and middle size cuttings.

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