Pore Pressure Prediction and Its Relationship with Rock Strength Parameters and Weight on Bit in Carbonate Reservoirs (A Case Study, South Pars Gas Field)

Khoshnevis-zadeh, Reza; Hajian, Alireza; Larki, Ehsan

doi:10.1007/s13369-020-05284-x

Cited by 6 publications

(2 citation statements)

References 31 publications

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“…After the pore pressure effect, the surface of the rock sample becomes rougher. At a ratio of 10 μm, obvious pores can be clearly observed, and there are microcracks with interlaced trends in some areas (5) After the effect of pore pressure, there are multiple pore and fissure concentrated areas in the rock sample, and the pore and fissure distributions are obviously found to be higher. It can be found that there are well-developed fissures that have extended to most part of the rock sample.…”

Section: Data Availabilitymentioning

confidence: 96%

“…As the depth of mining increases, deep mining faces the problems of high geotemperature, high hydraulic pressure, high ground stresses, and mining disturbance, among which high pore water pressure is an important factor [1][2][3]. In the oil and gas industry, pore pressure is generated by the fluid in the pores and fractures of rock mass during reservoir diagenesis [4,5]. Long-term pore pressure can lead to damage within the original rock [6] and a corresponding change in the physical characteristics of the rock mass, which makes the reservoir formation environment more complex and difficult to extract.…”

Section: Introductionmentioning

confidence: 99%

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Experimental Investigation of the Effect of Evenly Distributed Pore Pressure on Rock Damage

et al. 2022

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The effect of pore pressure on rock damage is a core problem in underground engineering. In this paper, the pseudotriaxial hydromechanical coupling experiment system is utilized to carry out the physical model experiment of the pore pressure on the rock damage, and the effect of evenly distributed pore pressure on rock strength and pore structure is analyzed. Compared with natural rock sample before the pore pressure effect, the uniaxial compressive strength is reduced by about 35.24%. Pore pressure decreases the strength of the rock and reduces its ability to resist deformation. The stress growth rate at the prepeak stage of the stress-strain curve for rock sample after pore pressure effect decreases. The peak strength decreases, and the strain corresponding to the peak stress increases. The plastic deformation characteristics of the sample are obvious. After the sample has macroscopically broken, the decline rate of postpeak stress slows down, and the residual strength decreases. The rock gradually changes from brittle failure mode to ductile failure mode. Through scanning electron microscopy (SEM) test and comparison analysis, it is found that after the pore pressure effect, the surface of the rock sample becomes rougher. There are multiple pore and fissure concentrated areas in the rock sample. Compared with the sample before the pore pressure effect, the number of pores with an equivalent diameter in the range of 2 μm-3 μm increases significantly. The proportion has increased from 7.7% to 19.1%, and the number has increased from 1468 to 4454. A large number of small-sized pores (less than 3 μm) are generated in the rock sample after the pore pressure effect. Therefore, the overall pore content of the rock sample increases.

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Section: Data Availabilitymentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of the Effect of Evenly Distributed Pore Pressure on Rock Damage

et al. 2022

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Pore pressure prediction in a carbonate reservoir: a case study from Potwar Plateau, Pakistan

Khan

Awais

Hussain

et al. 2022

J Petrol Explor Prod Technol

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Deep sedimentary successions, which are usually over-pressured, require accurate prediction of abnormal pressures to avoid catastrophic incidents, e.g., well blowouts; thus, pore pressure prediction (PPP) makes an important step for efficient reservoir modeling, cost-optimization and safe well-planning procedures in the hydrocarbon exploration. The objective of this study focuses on the estimation of formation pore pressure (PP) within the Eocene Chorgali Formation, using well logs data (from MYL-X1 and MYL-X2 wells) of Meyal Oil Field, Potwar Plateau, Pakistan, and its integration with outcrop, microscopic and seismic data. The formation PP is estimated from geophysical well logs (gamma-ray and sonic logs), by applying the widely used Eaton’s method. The pore pressure gradient (PPG) indicates the presence of pressured zone(s) in the Chorgali Formation in both wells. In MYL-X1, Chorgali Formation PPG and PP ranged from 9 to 13 lbs/gal and 5800 to 8400 psi, respectively, at about depth of 3760–3800 m. The reservoir Chorgali Formation in MYL-X2 wells also displayed pressure zone at about depth interval of 3820–3890 m with PPG and PP values of 8.9–11.6 lbs/gal and 5700–7500 psi, respectively; however, it indicated less pressure than MYL-X1. The synthesis of outcrop, microscopic, well logs and seismic data sets illustrates variations in pore pressure within the Eocene Chorgali Formation that is influenced and controlled by depositional, diagenetic and tectonic fabric among other factors. The variations in PP are necessary to determine to avoid any geologic disaster. Such incidents may cause potential loss during drilling operations in the geologically complicated settings of the Himalayan Fold-and-Thrust belt.

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Analyzing in situ stresses and wellbore stability in one of the south Iranian hydrocarbon gas reservoirs

Sobhani,

Kadkhodaie,

Nabi-Bidhendi

et al. 2024

J Petrol Explor Prod Technol

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This study aims to analyze in situ stresses and wellbore stability in one of the Iranian gas reservoirs by using well log data, including density, sonic (compressional and shear slowness), porosity, formation micro-image (FMI) logs, modular formation dynamics tester (MDT), and rock mechanical tests. The high burial depth, high pore pressure, and strike-slip stress regime of the field require an optimal design of geomechanical parameters based on an integrated data set consisting of static and dynamic data, which is available for this study. Firstly, poroelastic modulus and vertical stress were calculated. Afterward, the Eaton’s equation was used to estimate pore pressure from well logging data. The geomechanical parameters were also calibrated through the interpretation of image data, the use of the modular formation dynamics tester (MDT), and laboratory rock mechanic tests. Employing poroelastic equations, the lowest and highest horizontal stresses were calculated. It was shown that the maximum horizontal stress and minimum horizontal stress correspond to sigma H and sigma h, indicating the strike-slope fault regime. The findings of this research indicated that the equivalent mud weight (EMW) resulted in 10–13 ppg suitable for the Kangan Formation and 11–14 ppg suitable for the Dalan Formation. Additionally, the well azimuth in the NE-SW direction provided the best stability for drilling the encountered formations. Therefore, the results of this study serve as cost-effective tools in planning adjacent wells in carbonate formations of gas field to predict the wellbore stability and safe mud window.

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Pore Pressure Prediction and Its Relationship with Rock Strength Parameters and Weight on Bit in Carbonate Reservoirs (A Case Study, South Pars Gas Field)

Cited by 6 publications

References 31 publications

Experimental Investigation of the Effect of Evenly Distributed Pore Pressure on Rock Damage

Experimental Investigation of the Effect of Evenly Distributed Pore Pressure on Rock Damage

Pore pressure prediction in a carbonate reservoir: a case study from Potwar Plateau, Pakistan

Analyzing in situ stresses and wellbore stability in one of the south Iranian hydrocarbon gas reservoirs

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