Effect of kerogen on rock physics of immature organic-rich chalks

Shitrit, O.; Hatzor, Yossef H.; Feinstein, Shimon; Palchik, V.; Vinegar, Harold J

doi:10.1016/j.marpetgeo.2016.03.023

Cited by 19 publications

(21 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We previously showed that the porosity in the Zoharim section decreases with depth (Shitrit et al . ). The micrographs presented in Fig.…”

Section: Resultsmentioning

confidence: 97%

“…We previously found that the average kerogen density is 1.43 g/cm 3 (Shitrit et al . ). The error on

f_{k}

is estimated to 5.5%, accounting for the accuracy of TOC measurements, and reasonable ranges of kerogen density and

C_{k}

(±0.06 g/cm 3 and ±0.05, respectively).…”

Section: Methodsmentioning

confidence: 97%

“…The organic matter in the Zoharim section is almost entirely made of kerogen, so that organic content is considered equal to the kerogen content,

f_{k}

, computed by (Shitrit et al . )

f_{k} = \frac{ρ_{dry} TOC}{C_{k} ρ_{k}},

where ρ dry is the dry bulk density,

ρ_{k}

is the kerogen density and

C_{k}

is the carbon weight fraction in the organic matter (∼ 0.7). We previously found that the average kerogen density is 1.43 g/cm 3 (Shitrit et al .…”

Section: Methodsmentioning

confidence: 99%

“…; Shitrit et al . ). The Ghareb–Mishash chalk was found to have high porosity (20–45%) and high TOC (1–20 wt.%).…”

Section: Introductionmentioning

confidence: 97%

“…Previous petrophysical and mechanical studies of this rock were performed using core material from the Aderet and Zoharim wells in the Shefela basin (Bisnovat et al 2015;Shitrit et al 2016). The Ghareb-Mishash chalk was found to have high porosity (20-45%) and high TOC (1-20 wt.%).…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Static and dynamic elastic moduli of organic‐rich chalk

Shitrit

Hatzor

Feinstein

et al. 2019

Geophysical Prospecting

Self Cite

View full text Add to dashboard Cite

The elastic moduli and anisotropy of organic‐rich rocks are of great importance to geoengineering and geoprospecting of oil and gas reservoirs. In this paper, we probe into the static and dynamic moduli of the Ghareb–Mishash chalk through laboratory measurements and new analytical approaches. We define a new anisotropy parameter, ‘hydrostatic strain ratio’ (Ω), which describes the differential contraction of anisotropic rocks consequent to hydrostatic compression. Ω depends on the C11, C12, C13 and C33 stiffness constants of a transversely isotropic material, and therefore enables a unique insight into the anisotropic behaviour of TI rocks. Ω proves more sensitive to anisotropy within the weak anisotropy range, when compared with Thomsen's ε and γ parameters. We use Ω to derive static moduli from triaxial compression tests performed on a single specimen. This is done by novel employment of a hydrostatic‐deviatoric combination for transversely isotropic elastic stiffnesses. Dynamic moduli are obtained from acoustic velocities measurements. We find that the bedding‐normal velocities are described well by defining kerogen as the load‐supporting matrix in a Hashin–Shtrikman model (‘Hashin–Shtrikman (HS) kerogen’). The dynamic moduli of the Ghareb–Mishash chalk in dry conditions are significantly higher than the static moduli. The dynamic/static moduli ratio decreases from ∼4 to ∼2 with increasing kerogen content. Both the static and dynamic moduli decrease significantly with increasing porosity and kerogen content. The effect of porosity on them is two times stronger than the effect of kerogen.

show abstract

“…We previously showed that the porosity in the Zoharim section decreases with depth (Shitrit et al . ). The micrographs presented in Fig.…”

Section: Resultsmentioning

confidence: 97%

“…We previously found that the average kerogen density is 1.43 g/cm 3 (Shitrit et al . ). The error on

f_{k}

is estimated to 5.5%, accounting for the accuracy of TOC measurements, and reasonable ranges of kerogen density and

C_{k}

(±0.06 g/cm 3 and ±0.05, respectively).…”

Section: Methodsmentioning

confidence: 97%

“…The organic matter in the Zoharim section is almost entirely made of kerogen, so that organic content is considered equal to the kerogen content,

f_{k}

, computed by (Shitrit et al . )

f_{k} = \frac{ρ_{dry} TOC}{C_{k} ρ_{k}},

where ρ dry is the dry bulk density,

ρ_{k}

is the kerogen density and

C_{k}

is the carbon weight fraction in the organic matter (∼ 0.7). We previously found that the average kerogen density is 1.43 g/cm 3 (Shitrit et al .…”

Section: Methodsmentioning

confidence: 99%

“…; Shitrit et al . ). The Ghareb–Mishash chalk was found to have high porosity (20–45%) and high TOC (1–20 wt.%).…”

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Static and dynamic elastic moduli of organic‐rich chalk

Shitrit

Hatzor

Feinstein

et al. 2019

Geophysical Prospecting

Self Cite

View full text Add to dashboard Cite

show abstract

Acoustic and Petrophysical Evolution of Organic-Rich Chalk Following Maturation Induced by Unconfined Pyrolysis

et al. 2017

View full text Add to dashboard Cite

Water-Weakening and Time-Dependent Deformation of Organic-Rich Chalks

et al. 2023

View full text Add to dashboard Cite

The Ghareb Formation is a shallowly buried porous chalk in southern Israel that is being considered as a host rock for a geologic nuclear waste repository. Setup and operation of a repository will induce significant mechanical, hydrological and chemical perturbations in the Ghareb. Developing a secure repository requires careful characterization of the rock behavior to different loads. To characterize hydromechanical behavior of the Ghareb, several short- and long-term deformation experiments were conducted. Hydrostatic loading tests were conducted both dry and water-saturated, using different setups to measure elastic properties, time-dependent behavior, and permeability. A set of triaxial tests were conducted to measure the elastic properties and rock strength under differential loading at dry and water-saturated conditions. The hydrostatic tests showed the Ghareb began to deform inelastically around 12–15 MPa, a relatively low effective pressure. Long-term permeability measurements demonstrated that permeability declined with increasing effective pressure and was permanently reduced by ~ 1 order of magnitude after unloading pressure. Triaxial tests showed that water saturation significantly degrades the rock properties of the Ghareb, indicating water-weakening is a significant risk during repository operation. Time-dependent deformation is observed during hold periods of both the hydrostatic and triaxial tests, with deformation being primarily visco-plastic. The rate of deformation and permeability loss is strongly controlled by the effective pressure as well. Additionally, during holds of both hydrostatic and triaxial tests, it is observed that when water-saturated, radial strain surpassed axial strain when above effective pressures of 13–20 MPa. Thus, deformation anisotropy may occur in situ during operations even if the stress conditions are hydrostatic when above this pressure range.

show abstract

Effect of kerogen on rock physics of immature organic-rich chalks

Cited by 19 publications

References 24 publications

Static and dynamic elastic moduli of organic‐rich chalk

Static and dynamic elastic moduli of organic‐rich chalk

Acoustic and Petrophysical Evolution of Organic-Rich Chalk Following Maturation Induced by Unconfined Pyrolysis

Water-Weakening and Time-Dependent Deformation of Organic-Rich Chalks

Contact Info

Product

Resources

About