Estimation of Mechanical Rock Properties from Laboratory and Wireline Measurements for Sandstone Reservoirs

Mechanical rock properties are essential to minimize many well problems during drilling and production operations. While these properties are crucial in designing optimum mud weights during drilling operations, they are also necessary to reduce the sanding risk during production operations. This study has been conducted on the Zubair sandstone reservoir, located in the south of Iraq. The primary purpose of this study is to develop a set of empirical correlations that can be used to estimate the mechanical rock properties of sandstone reservoirs. The correlations are established using laboratory (static) measurements and well logging (dynamic) data. The results support the evidence that porosity and sonic travel time are consistent indexes in determining the mechanical rock properties. Four correlations have been developed in this study which are static Young’s modulus, uniaxial compressive strength, internal friction angle, and static Poisson’s ratio with high performance capacity (determination coefficient of 0.79, 0.91, 0.73, and 0.78, respectively). Compared with previous correlations, the current local correlations are well-matched in determining the actual rock mechanical properties. Continuous profiles of borehole-rock mechanical properties of the upper sand unit are then constructed to predict the sand production risk. The ratio of shear modulus to bulk compressibility (G/Cb) as well as rock strength are being used as the threshold criterion to determine the sanding risks. The results showed that sanding risk or rock failure occurs when the rock strength is less than 7250 psi (50 MPa) and the ratio of G/Cb is less than 0.8*1012 psi2. This study presents a set of empirical correlations which are fewer effective costs for applications related to reservoir geomechanics.

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Mechanical Rock Properties Estimation for Carbonate Reservoir Using Laboratory Measurement: A Case Study from Jeribe, Khasib and Mishrif Formations in Fauqi Oil Field

Iraqi Geological Journal ◽

10.46717/igj.54.1e.8ms-2021-05-29 ◽

2021 ◽

Vol 54 (1E) ◽

pp. 88-102

Author(s):

Qahtan Abdul Aziz ◽

Hassan Abdul Hussein

Keyword(s):

Mechanical Properties ◽

Bulk Density ◽

Depositional Environments ◽

Carbonate Reservoir ◽

Oil Field ◽

Well Logs ◽

Rock Properties ◽

Petrophysical Properties ◽

Empirical Correlations ◽

Rock Mechanical Properties

Estimation of mechanical and physical rock properties is an essential issue in applications related to reservoir geomechanics. Carbonate rocks have complex depositional environments and digenetic processes which alter the rock mechanical properties to varying degrees even at a small distance. This study has been conducted on seventeen core plug samples that have been taken from different formations of carbonate reservoirs in the Fauqi oil field (Jeribe, Khasib, and Mishrif formations). While the rock mechanical and petrophysical properties have been measured in the laboratory including the unconfined compressive strength, Young's modulus, bulk density, porosity, compressional and shear -waves, well logs have been used to do a comparison between the lab results and well logs measurements. The results of this study revealed that petrophysical properties are consistent indexes to determine the rock mechanical properties with high performance capacity. Different empirical correlations have been developed in this study to determine the rock mechanical properties using the multiple regression analysis. These correlations are UCS-porosity, UCS-bulk density, UCS-Vs, UCs-Vp Es-Vs, Es-Vp, and Vs-Vp. (*). For example, the UCS-Vs correlation gives a good determination coefficient (R2= 0.77) for limestone and (R2=0.94) for dolomite. A comparison of the developed correlations with literature was also checked. This study presents a set of empirical correlations that can be used to determine and calibrate the rock mechanical properties when core samples are missing or incomplete.

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Integration of Chemofacies and Rock Mechanical Properties Using Machine Learning Algorithms: Implications for Geomechanics and Hydraulic Fracture Stimulations in Paleozoic Formations, Saudi Arabia

10.2118/205951-ms ◽

2021 ◽

Author(s):

Maaruf Hussain ◽

Abduljamiu Amao ◽

Khalid Al-Ramadan ◽

Sunday Olatunji ◽

Ardiansyah Negara

Keyword(s):

Machine Learning ◽

Mechanical Properties ◽

Saudi Arabia ◽

Spatial Distribution ◽

Chemical Composition ◽

Rock Strength ◽

Machine Learning Algorithms ◽

Unconventional Reservoirs ◽

Geochemical Properties ◽

Rock Mechanical Properties

Abstract The knowledge of rock mechanical properties is critical to reducing drilling risk and maximizing well and reservoir productivity. Rock chemical composition, their spatial distribution, and porosity significantly influenced these properties. However, low porosity characterized unconventional reservoirs as such, geochemical properties considerably control their mechanical behavior. In this study, we used chemostratigraphy as a correlation tool to separate strata in highly homogenous formations where other traditional stratigraphic methods failed. In addition, we integrated the chemofacies output and reduced Young's modulus to outline predictable associations between facies and mechanical properties. Thus, providing better understanding of lithofacies-controlled changes in rock strength that are useful inputs for geomechanical models and completions stimulations.

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The Influence of Kaolinite - Illite toward mechanical properties of Claystone

Open Geosciences ◽

10.1515/geo-2019-0035 ◽

2019 ◽

Vol 11 (1) ◽

pp. 440-446

Author(s):

Supandi Supandi ◽

Zufialdi Zakaria ◽

Emi Sukiyah ◽

Adjat Sudradjat

Keyword(s):

Mechanical Properties ◽

Physical Properties ◽

Void Ratio ◽

Correlation Coefficients ◽

Physical And Mechanical Properties ◽

Friction Angle ◽

Engineering Properties ◽

Rock Properties ◽

Triaxial Tests ◽

Mineralogical Characteristics

Abstract This study investigates the relationship between clay minerals (kaolinite and illite) and rock properties of the claystone, including both mechanical (cohesion, friction angle, stress, and strain) and physical properties (natural water content, void ratio, and wet density), belonging to Warukin Formation of Kalimantan, Indonesia. Mineralogical characteristics of these rocks were studied using petrological and X-ray diffraction techniques, whereas the mechanical and physical properties were tested by conducting uniaxial and triaxial tests. Relationship among the variables was determined using correlation coefficients. It was observed that the mineralogy of the rocks pose strong constraints on their engineering properties. The results showed that an increase in illite content decreases cohesion, friction angle, strength, and safety factor; and increases natural moisture content, void ratio, and wet density. Although illite content of these rocks was just about 10.8% of the total minerals, it has significantly contributed to the modification of physical and mechanical properties. In contrast, kaolinite did not have a significant impact; since the correlation between various parameters was significantly low (correlation coefficient was much less, <0.3). Therefore while selecting the materials for geotechnical engineering applications, illite emerges as a safer alternative to kaolinite, especially when its concentration is less than 10.8% of the total rock mass.

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VARIATION OF THE INTRINSIC ROCK PROPERTIES ON HOEK-BROWN FAILURE CRITERION PARAMETERS

Rudarsko-geološko-naftni zbornik ◽

10.17794/rgn.2021.4.7 ◽

2021 ◽

Vol 36 (4) ◽

pp. 73-84

Author(s):

Sina Salajegheh ◽

Kourosh Shahriar ◽

Hossein Jalalifar ◽

Kaveh Ahangari

Keyword(s):

Inverse Relationship ◽

Rock Strength ◽

Contact Stiffness ◽

Friction Angle ◽

Failure Criteria ◽

Rock Properties ◽

Fundamental Parameter ◽

Constant Parameter ◽

Rock Failure Criteria ◽

Triaxial Compressive Strength

The Hoek-Brown (H-B) criterion is one of the most commonly used rock failure criteria in recent years. This criterion includes a constant parameter called mi which is a fundamental parameter for estimating rock strength. Due to the importance of the mi parameter in the H-B criterion, it is necessary to conduct comprehensive studies on various aspects of the effect of this parameter on the behavior of rocks. Therefore, in this study, using numerical simulation of the Triaxial Compressive Strength (TCS) tests in PFC-2D code, the effects of microscopic properties of different rocks on the H-B parameter mi have been studied. Based on the results of this study, it was found that the effects of micro-parameters on the H-B parameter mi can be different depending on the type of rock, however this parameter has an inverse relationship to the micro-parameters of bond tensile strength and bond fraction of the rocks. Also, the mi parameter increases with an increase in the micro-parameters of the friction coefficient, the friction angle, the particle contact modulus, and the contact stiffness ratio of rocks.

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An Innovative Methodology for Estimating Rock Mechanical Properties from Weight or Volume Fractions of Mineralogy and its Application to Middle East Reservoirs

10.2118/204687-ms ◽

2021 ◽

Author(s):

Umesh Prasad ◽

Amer Hanif ◽

Ian McGlynn ◽

Frank Walles ◽

Ahmed Abouzaid ◽

...

Keyword(s):

Mechanical Properties ◽

Public Domain ◽

New Method ◽

Rock Properties ◽

Upper And Lower Bounds ◽

Geomechanical Model ◽

Volume Fractions ◽

Fluid Properties ◽

Tight Formations ◽

Rock Mechanical Properties

Abstract The influences of mineralogy on rock mechanical properties have profound application in oil and gas exploration and production processes, including hydraulic fracturing operations. In conventional resources, the rock mechanical properties are predominantly controlled by porosity; however, in unconventional tight formations, the importance of mineralogy as a function of rock mechanical properties has not been fully investigated. In unconventional tight formations, mechanical properties are often derived from mineralogy weight fraction together with the best estimate of porosity, assumption of fluid types, the extent of pore fillings, and fluid properties. These properties are then adjusted for their volumetric fractions and subsequently calibrated with acoustics or geomechanical lab measurements. A new method is presented that utilizes mineralogy weight fractions (determined from well logs or laboratory measurements). This process uses public domain information of minerals using Voigt and Reuss averaging algorithms as upper and lower bounds, respectively. An average of these bounds (also known as Hill average) provides a representative value for these parameters. Further, based on isotropic conditions, all the elastic properties are calculated. A typical output consisting of bulk-, shear-, and Young's - modulus, together with Poisson's ratio obtained from traditional methods of volume fractions and this new method using weight fractions is discussed and analyzed along with the sensitivity and the trends for individual rock properties. Furthermore, corresponding strengths, hardness, and fracture toughness could also be estimated using well known public domain algorithms. Data from carbonate reservoirs has been discussed in this work. This method shows how to estimate grain compressibility that can be challenging to be measured in the lab for unconventional tight rock samples. In low-porosity samples, the relative influence of porosity is negligible compared to the mineralogy composition. This approach reduces several assumptions and uncertainties associated with accurate porosity determination in tight rocks as it does not require the amount of pore fluids and fluid properties in calculations. The grain-compressibility and bulk-compressibility (measured by hydrostatic tests in the laboratory on core plugs or calculated from density and cross-dipole log) are used to calculate poroelastic Biot's coefficient, as this coefficient will be used to calculate in-situ principal effective stresses (overburden, minimum horizontal, and maximum horizontal stresses), which are, together with rock properties and pore pressure, constitutes the geomechanical model. The geomechanical model is used for drilling, completions, and hydraulic fracture modeling, including wellbore stability, and reservoir integrity analyses.

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Study on Mechanical Behavior of Jurassic Frozen Sandstone in Western China Based on NMR Porosity

Journal of Chemistry ◽

10.1155/2020/2936932 ◽

2020 ◽

Vol 2020 ◽

pp. 1-11

Author(s):

Maoyan Ma ◽

Yishun Huang ◽

Guangyong Cao ◽

Jian Lin ◽

Shiliang Xu

Keyword(s):

Mechanical Properties ◽

Growth Rate ◽

Low Temperature ◽

Rock Strength ◽

Tracking System ◽

Triaxial Compression ◽

Confining Pressure ◽

Western China ◽

Compression Tests ◽

Rock Mechanical Properties

Study of frozen rock mechanical properties is necessary for safe application of the artificial ground freezing method in excavation of Chinese western water-rich soft rock layers. Triaxial compression tests and NMR test for samples from the western Jurassic sandstone were performed to investigate rock mechanical properties affected by low temperature and confining pressure. The results show mechanical parameters such as peak strength, cohesion, internal friction angle, residual strength, and elasticity modulus increased with the decreasing temperature under stable pressure, and the above parameters increased with the increasing confining pressure at a certain temperature. In particular, the growth rate of the rock strength would decline when the temperature was below −10°C in this study. Strength attenuation coefficients increased with the decreasing temperature, which indicated higher brittleness, whereas plastic characters got more obvious with the increasing confining pressure at a stable temperature. Furthermore, during the first two freezing stages, porosity decreased sharply with obvious increase of pore (crack) ice content, while porosity varied little at the third stage, which was the reason for the growth rate of rock strength declining with continuous low temperature from microcosmic point of view.

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Effect of Cryogenic Treatment Thermal Shock on Rock Dynamic Elastic Properties and Permeability of Wolfcamp Core Samples – An Experimental Study

10.2118/200823-ms ◽

2021 ◽

Author(s):

Mahdi Ramezanian ◽

Hossein Emadi

Keyword(s):

Mechanical Properties ◽

Thermal Shock ◽

Elastic Properties ◽

Cryogenic Treatment ◽

Xrd Analysis ◽

Rock Properties ◽

Core Samples ◽

Permeability Enhancement ◽

Rock Mechanical Properties ◽

Dynamic Elastic Properties

Abstract A few researches have been conducted to study effects of cryogenic treatment (known as thermal shocking) on unconventional rock properties, while they have been extensively studied in geothermal projects. The results show that cryogenic treatment significantly alters the rock mechanical properties by creation of new cracks owing to thermally induced stresses resulting in the permeability enhancement. In this laboratory study, effects of cryogenic treatment (thermal shocking) on permeability and dynamic elastic properties of three Wolfcamp core samples (one outcrop and two downhole samples) at downhole conditions were experimentally evaluated. Permeability and dynamic rock mechanical properties were measured before and after conducting each cycle of thermal shock. Using X-ray powder diffraction (XRD) analysis, the mineral compositions of the cores were determined. The results demonstrate that implementing the thermal shock technique on the core samples results in increasing their permeability and ductility.

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Geomechanical Properties Estimation Utilizing Artificial Intelligence Prediction Tool

10.2118/204672-ms ◽

2021 ◽

Author(s):

Mohammed Alabbad ◽

Mohammad Alqam ◽

Hussain Aljeshi

Keyword(s):

Mechanical Properties ◽

Oil And Gas ◽

Oil And Gas Industry ◽

Significant Loss ◽

Wellbore Stability ◽

Rock Properties ◽

Ann Model ◽

Full Field ◽

Geomechanical Properties ◽

Rock Mechanical Properties

Abstract Drilling and fracturing are considered to be one of the major costs in the oil and gas industry. Cost may reach tens of millions of dollars and improper design may lead to significant loss of money and time. Reliable fracturing and drilling designs are governed with decent and representative rock mechanical properties. Such properties are measured mainly by analyzing multiple previously cored wells in the same formation. The nature of the conducted tests on the collected plugs are destructive and samples cannot be restored after performing the rock mechanical testing. This may disable further evaluation on the same plugs. This study aims to build an artificial neural network (ANN) model that is capable of predicting the main rock mechanical properties, such as Poisson's ratio and compressive strength from already available lab and field measurements. The log data will be combined together with preliminary lab rock properties to build a smart model capable of predicting advance rock mechanical properties. Hence, the model will provide initial rock mechanical properties that are estimated almost immediately and without undergoing costly and timely rock mechanical laboratory tests. The study will also give an advantage to performing preliminary estimates of such parameters without the need for destructive mechanical core testing. The ultimate goal is to draw a full field geomechanical mapping with this tool rather than having localized scattered data. The AI tool will be trained utilizing representative sets of rock mechanical data with multiple feed-forward backpropagation learning techniques. The study will help in localizing future well location and optimizing multi-stage fracturing designs. These produced data are needed for upstream applications such as wellbore stability, sanding tendency, hydraulic fracturing, and horizontal/multi-lateral drilling.

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Field Scale Geo-Mechanical Analysis To Identify Fracture Sweet Spots Within Deccan Trap, Western Onshore, India

10.4043/31206-ms ◽

2021 ◽

Author(s):

Rajeev Ranjan Kumar ◽

Sanjoy Kumar Mukherjee ◽

S. K Biswal ◽

Rajasekar V ◽

Surej Kumar Subbiah ◽

...

Keyword(s):

Mechanical Properties ◽

Deccan Trap ◽

Fracture Network ◽

Fracture Analysis ◽

Rock Properties ◽

Main Challenge ◽

Slip Tendency ◽

Stress Profiles ◽

Rock Mechanical Properties ◽

Sweet Spots

Abstract Hydrocarbon exploration continues to venture into new avenues. This paper elaborates the 3D geomechanical study carried out to identify sweet spots in Deccan Trap Basalts in depth ranging from 500m-1100m in Cambay basin field of India. The main challenge is wide variation in the rock mechanical properties and stress profiles along various azimuths resulting from different tectonic incidents over the geological ages. Several drilling complications and held ups during electro logging in highly deviated wells are also reported. The normal fault tectonic framework has the imprint of two sets of faults viz., NNW-SSE and ENE-WSW. Deccan Trap acts as reservoirs due to the presence of connected open fracture network and to assess the potential reserves a comprehensive 3D Critically stressed fracture analysis has been performed using 3D numerical simulation-based rock properties, in-situ stress and seismic data. Open hole geophysical logs like sonic dipole and borehole images have been used to estimate rock mechanical properties and stress profiles in 18 key wells. Available core data of Basalt in the area have been used for dynamic to static rock properties estimation along with available published literature data. Critically stressed fracture analysis using 1D MEM outputs and dips dataset has been performed at well scale to history match production logging and testing results of 23 wells located in different fault blocks. 3D stress model has been built using plasticity model while taking into account faults and fracture sets. Utilizing 3D Geomechanical properties and Discrete fracture network model, critically stressed fracture sets have been identified across the field with slip tolerance and effective drawdown pressures. The study suggests that structurally high locations are good producers if seals are present above Trap. Sub-horizontal fractures have a higher closing tendency with decline in pressure in layers with SHmax>SHmin>Sv inside stiff Trap layer. There is variation of slip tolerance in the range of 0.2-1.4 in fracture sets which indicates slip tendency to be varying both vertically and laterally. Faults with ENE-WSW strike seem to be fluid migratory conduits and their intersection with NNW-SSE discontinuities are the areas where fracture sets have a higher slip tendency. Most of the producing layers are within 25m-55m of Trap with water being encountered at deeper depth intervals. These are mostly weathered fractured layers within the trap. The stress map suggests rotation of the maximum horizontal stress azimuth from NW to E which also affects fracture intensity in the field. Few fracture sets have tendency to be slip prone even with depletion up to 300psi-800psi while others will require stimulation or acid clean up job. Eight exploration wells drilled based on the study have shown good flow rate on initial well testing in the area providing validation to the study.

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Macroprobe Mode for the Study of Segregation in Steels

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100134909 ◽

1990 ◽

Vol 48 (2) ◽

pp. 260-261

Author(s):

Auclair Gilles ◽

Benoit Danièle

Keyword(s):

Mechanical Properties ◽

Spatial Distribution ◽

High Performance ◽

Volume Fraction ◽

Sheet Steel ◽

Acquisition Time ◽

Chemical Information ◽

X Ray ◽

Accurate Quantitative Analysis ◽

Optical Micrographs

During these last 10 years, high performance correction procedures have been developed for classical EPMA, and it is nowadays possible to obtain accurate quantitative analysis even for soft X-ray radiations. It is also possible to perform EPMA by adapting this accurate quantitative procedures to unusual applications such as the measurement of the segregation on wide areas in as-cast and sheet steel products.The main objection for analysis of segregation in steel by means of a line-scan mode is that it requires a very heavy sampling plan to make sure that the most significant points are analyzed. Moreover only local chemical information is obtained whereas mechanical properties are also dependant on the volume fraction and the spatial distribution of highly segregated zones. For these reasons we have chosen to systematically acquire X-ray calibrated mappings which give pictures similar to optical micrographs. Although mapping requires lengthy acquisition time there is a corresponding increase in the information given by image anlysis.

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