The effect of heterogeneity on NMR derived capillary pressure curves, case study of Dariyan tight carbonate reservoir in the central Persian Gulf

Hosseini, Mehdi; Tavakoli, Vahid; Nazemi, Maziyar

doi:10.1016/j.petrol.2018.08.054

Cited by 34 publications

(9 citation statements)

References 27 publications

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“…Carbonate sequences, including that at Nash Point, are commonly composed of interbedded layers of limestone and calcareous shales (Galvis et al 2017;Sosa et al 2017;Forbes Inskip et al 2018;Hosseini et al 2018). In such sequences, there are likely significant contrasts in the fracture properties of the different strata and this will affect how fractures propagate across the sequence as a whole.…”

Section: Implications For Fracture Propagation Through Layered Rock Sequencesmentioning

confidence: 99%

“…By contrast, where limestones are not naturally fractured and the matrix permeability is low, hydraulic stimulation or hydraulic fracturing is commonly required to enhance permeability and increase fluid flow. Examples of limestone reservoirs which are considered tight include the Taq Taq, Kirkuk, Jambur, Khabaz and Bai Hassan oil fields in the Zagros fold belt (Rashid et al 2017) and the Dariyan formation in the central Persian Gulf (Hosseini et al 2018). In both situations, it is important to know the fracture properties of the limestone, firstly to determine fracture spacing, aperture and tortuosity, and thus accurately estimate reservoir porosity and permeability, and secondly to understand how and when fractures will propagate during anthropogenic stimulation.…”

Section: Introductionmentioning

confidence: 99%

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Fracture Properties of Nash Point Limestone and Implications for Fracturing of Layered Carbonate Sequences

Inskip

Meredith

2021

Rock Mech Rock Eng

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Carbonate reservoirs accommodate a significant proportion of global hydrocarbon reserves. However they are often tight and permeability is therefore usually dependent on either flow through existing fractures or through those produced by hydraulic stimulation. Hence, understanding how fracture networks develop in carbonate reservoir rocks is key to efficient and effective production. However, despite their prevalence as reservoir rocks, there is a paucity of data on key fracture properties of carbonate rocks, particularly in more than one orientation. Here, therefore we report measurements of both the tensile strength and fracture toughness of Nash Point limestone in the three principal fracture orientations to determine what effect any mechanical anisotropy might have on fracture propagation. We find Nash Point limestone to be essentially isotropic in terms of both its microstructure and its fracture properties. When comparing the fracture toughness of Nash Point limestone with that of others limestones, we find that fracture toughness decreases with increasing porosity, although this dependency is not as strong as found in other porous rocks. Finally, as many so-called carbonate reservoirs actually comprise layered sequences, we extend our analysis to consider the layered sequence of limestones and shales at Nash Point. We find that the fracture toughness of Nash Point limestone is higher than Nash Point shale but that the fracture energy is lower. We therefore discuss how the implications of fracturing through multi-layered sequences could be explored in future work.

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Section: Implications For Fracture Propagation Through Layered Rock Sequencesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Fracture Properties of Nash Point Limestone and Implications for Fracturing of Layered Carbonate Sequences

Inskip

Meredith

2021

Rock Mech Rock Eng

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“…Pore-throat radius obtained using the Laplace equation after the differentiation gives pore-throat size distribution (PTSD) (Hosseini et al 2018;Nazemi et al 2019). For each porethroat size, the numbers obtained from PTSD are between 0 and 1.0.…”

Section: Pore-throat Size Distributionmentioning

confidence: 99%

Diagenetic impacts on hydraulic flow unit properties: insight from the Jurassic carbonate Upper Arab Formation in the Persian Gulf

Sharifi-Yazdi

Rahimpour‐Bonab

Nazemi

et al. 2020

J Petrol Explor Prod Technol

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The Upper Arab reservoir in the central Persian Gulf was examined for depositional, diagenetic, sequence stratigraphic and petrophysical features. This succession is composed of eight sedimentary facies that deposited on a carbonate ramp. Three-third-order sequences prograded across the Late Jurassic Arab Platform. This interval was complicated by multiple diagenetic phases including eogenesis and mesogenesis that strongly influenced reservoir properties. Dolomitization, dissolution, cementation and compaction are major diagenetic processes which played an essential role in increasing or decreasing reservoir quality. Four hydraulic flow units (HFU) were determined by flow zone indicator approach for evaluation of the reservoir quality. In addition to depositional features, diagenetic alterations have changed general HFUs characterizations such as porosity, permeability and pore-throat size. Likewise, via Lucia classification, HFUs of the Arab reservoir were grouped based on the integration of geological and petrophysical attributes in detail. Among diagenetic processes, dolomitization and dissolution have positive effects while cementation and stylolitization have a negative effect on HFUs characteristics in the studied reservoir. Put another way, since diagenetic alterations lead to the intensification of heterogeneity in carbonate reservoir, prediction of the relationship between pore type and pore throat size is a problematic issue. Recognition of the hydraulic flow units considered as a practical tool for grouping reservoir rocks and characterizing heterogeneity using porosity and permeability relationship. Finally, specifying of the contribution of various diagenetic imprints in each hydraulic flow unit in a sequence stratigraphic framework results in a conceptual reservoir model that could predict reservoir quality variations across the field.

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“…It is an important content in reservoir evaluation . At present, nuclear magnetic resonance (NMR) and mercury injection capillary pressure(MICP) are major methods of characterizing the pore structure. − …”

Section: Introductionmentioning

confidence: 99%

Variable Dimension Fractal-Based Conversion Method between the Nuclear Magnetic Resonance T₂ Spectrum and Capillary Pressure Curve

Xie

Yin²,

Wang

et al. 2020

Energy Fuels

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Pore structure is the primary control factor of pore fluid distribution and flow capacity. It is an important content in reservoir evaluation. The capillary pressure curve is a major method to obtaining pore structure characteristics. The NMR T2 spectrum reflects pore size distribution. Both of them have a connection. Investigating methods of converting the NMR T2 spectrum into a capillary pressure curve is the key step to use nuclear magnetic resonance (NMR) logging data to quantitatively characterize the pore structure. The pore throat size distribution obtained by the NMR T2 spectrum and capillary pressure curve has fractal features. However, studies about the relationship between the capillary pressure curve and NMR T2 spectrum by the fractal characteristic have not been reported. This paper studies the relationship between the capillary pressure curve and NMR T2 spectrum by the fractal characteristic and proposes a method of converting the NMR T2 spectrum to the capillary pressure curve. To fully consider the influence of the pore structure, the dimension coefficient is set to be a variable that is related to the pore structure. The proposed model is verified by 20 rock samples in Nanpu sag, China by comparing the new method of calculate capillary pressure curves and experimental capillary pressure curves. Results show that the new method improves the accuracy of the conversion method between the NMR T2 spectrum and capillary pressure curve in the complex pore structure reservoirs. This research provides a new way to enrich pore structure characteristic parameters for high-precision reservoir evaluation and has certain guidance and reference significance for the research work of petrophysics, reservoir evaluation, and NMR logging data application.

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The effect of heterogeneity on NMR derived capillary pressure curves, case study of Dariyan tight carbonate reservoir in the central Persian Gulf

Cited by 34 publications

References 27 publications

Fracture Properties of Nash Point Limestone and Implications for Fracturing of Layered Carbonate Sequences

Fracture Properties of Nash Point Limestone and Implications for Fracturing of Layered Carbonate Sequences

Diagenetic impacts on hydraulic flow unit properties: insight from the Jurassic carbonate Upper Arab Formation in the Persian Gulf

Variable Dimension Fractal-Based Conversion Method between the Nuclear Magnetic Resonance T₂ Spectrum and Capillary Pressure Curve

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The effect of heterogeneity on NMR derived capillary pressure curves, case study of Dariyan tight carbonate reservoir in the central Persian Gulf

Cited by 34 publications

References 27 publications

Fracture Properties of Nash Point Limestone and Implications for Fracturing of Layered Carbonate Sequences

Fracture Properties of Nash Point Limestone and Implications for Fracturing of Layered Carbonate Sequences

Diagenetic impacts on hydraulic flow unit properties: insight from the Jurassic carbonate Upper Arab Formation in the Persian Gulf

Variable Dimension Fractal-Based Conversion Method between the Nuclear Magnetic Resonance T2 Spectrum and Capillary Pressure Curve

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Variable Dimension Fractal-Based Conversion Method between the Nuclear Magnetic Resonance T₂ Spectrum and Capillary Pressure Curve