Petrophysical Measurements on Shales Using NMR

Martı́nez, G.; Davis, Lorne A.

doi:10.2523/62851-ms

Cited by 11 publications

(5 citation statements)

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“…Several authors have used NMR to study porosity in shales (Martinez et al, (2000), Odusina et al, (2011), Sulucarnain et al, (2012 and Tinni et al, (2014)). Tinni et al, (2014) have used NMR to demonstrate that brine can enter both organic and inorganic pore systems at pressures less than 7000 psia while dodecane cannot enter the clay pores, even at 7000 psia.…”

Section: Methodsmentioning

confidence: 99%

NMR Investigation of Pore Structure in Gas Shales

Gannaway

2014

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In shales, the wettability contrast between water wet pores located between clay particles, oil wet organic pores and mixed wettability pores located at the interface between clays and organic matter, can be exploited to quantify the porosity associated with each pore system. In order to quantify the different types of porosity, the NMR T 2 spectra of 5 Barnett shale samples have been acquired, both in their native state, after dodecane saturation at 3000 psia, and after immersion in a 65% MnCl 2 aqueous solution. These NMR spectra were acquired with Tau ϭ 57 sec on a 2MHz instrument. 65% MnCl 2 aqueous solution has been found to exhibit no NMR signal and it does not mix with dodecane.All the samples displayed a unimodal T 2 distribution in their native state with a peak around 0.2 ms. This NMR peak is generally associated with clay pores. After dodecane saturation the development of a second peak around 5 ms forms. These two NMR peaks decreased after immersion in the MnCl 2 solution. MnCl 2 imbibition decreases the NMR water signal as it diffuses into the existing water in clay-dominated pores, and decreases the mixed pore system signal by a displacement process. The true organic pores are not affected by the MnCl 2 solution because an aqueous, water-based solution cannot displace dodecane by simple imbibition in an oil-wet pore. After 30 days of MnCl 2 imbibition the signal remaining on the peak at 5 ms is due to true organic pores. Also, this organic pore system displayed a positive relationship with the TOC of each sample.Upon placing samples in both a vacuum ϭ 4x10 -6 mTorr and 150°C for 2 weeks, the remaining NMR peak around 0.2 ms reached a threshold beyond which it could not be reduced. These NMR results mimicked the results achieved chemically by using a 65% MnCl 2 aqueous solution for the same NMR peak. These two experimental results, in conjunction with an understanding that the NMR peak around 0.2 ms represents clay dominated pores, yield support to the notion that the remaining peak around 0.2 ms (after 1 month of MnCl 2 aqueous solution imbibition) represents clay-bound water.Ultimately, this study allows for the quantification of effective porosity, inorganic porosity, organic porosity, the porosity at the inorganic-organic interface and clay-bound water.

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Section: Methodsmentioning

confidence: 99%

NMR Investigation of Pore Structure in Gas Shales

Gannaway

2014

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“…One high peak is at faster relaxation times less than 1 ms and the other with lower magnetization at slower relaxation times at about 10 ms as shown in Figure 4.15. The same bi-model distribution has also been observed by Martinez et al (2000). They studied the distribution of shale samples saturated with DI water and noticed the shift in some samples as a result of the change in the surface to volume pore ratios.…”

Section: Transverse Relaxation Time (T 2 ) Distribution Curvesmentioning

confidence: 58%

A High Field Solid-State Nuclear Magnetic Resonance Experimental Study for Clay and Shale Swelling

Alzahrani

2014

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The development of the shale resources faces many problems related to their complex structure and challenging conditions. Drilling and fracturing operations suffer from the swelling tendency of clays and shale formations. The expansion mechanisms of clays have been discussed in detail in the literature and several theories have been developed to predict the swelling in shales. The crystalline (interlayer), double-layer, and the layers breakage/formation swelling mechanisms are the mechanisms that are the most contributing for the clay swelling. They all depend on the ionic concentration of the system. Low frequency NMR technique has been used in the industry mainly to determine the rock properties. NMR has also been used to determine the chemistry of the matters, especially in high frequency fields in chemistry and other scientific applications. Yet, to the author's knowledge, there has been no high field NMR study exists to describe the swelling behavior of the clays. In this study, we conducted an experimental investigation to determine the feasibility of high frequency NMR measurements in characterizing the expansive behavior of pure clays and shale formations. Mainly, the benefits of utilizing the high field NMR for studying the swelling behavior of clays have been investigated and NMR data was collected and analyzed (e.g. relaxation times and distributions) for various liquid/clay systems. NMR data was also correlated to petrophysical and acoustic properties of pure clays and shales reported in the literature. An ultimate goal of this work is to evaluate the feasibility of the high field NMR use for characterization of the unconventional resource shale systems, in particular the Eagle Ford shale.In this study, high field NMR has been used to determine several clay and Eagle Ford shale structure and to measure the relaxation times of dry and saturated samples. Moreover, the iv relaxation time distribution curves have been used to identify the dominant swelling mechanism(s) taking place in the pure clays studied. Our study concentrates on the pure montmorillonite as it has the highest affinity to liquids. Few kaolinite and Eagle Ford shale samples have also been investigated to compare to the montmorillonite results and to present NMR data utilization in unconventional resource characterization.

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“…NMR technology has been proved to be a good technique for studying the reservoir engineering properties of rocks (Martinez and Davis, 2000;Sigal and Odusina, 2011;Zhou et al, 2012;Washburn and Birdwell, 2013). In this study, the crosswise relaxation time t 2 distribution of three samples was obtained through NMR measurement.…”

Section: Knmentioning

confidence: 98%