Study of the Influence of Change in the Sandstone and Aleurolite Collector Properties on the Geological Modeling Quality

The initial data when creating both geological and hydrodynamic reservoir models can lead to errors in the modeling results and the subsequent distortion of the economic assessment and prospects of an oil or gas field. In order to improve the predictive reliability of reservoir hydrodynamic models, a core material study for the Tula object of four fields at the Babkinskaya anticline was carried out. The ratio analysis of porosity (Kp), rock density () and permeability (Kperm) for sandstones and aleurolites was carried out. Using a statistical core sampling based on porosity, density and permeability parameters, a separation by sedimentation processes was carried out for all considered lithological differences. For aleurolite and sandstone, we could talk about the differentiation of characteristics in the process of reservoir properties formation. The values of the parameters Kp, and Kperm, determined from laboratory core studies, were combined into a single statistical sample for the possibility of developing a methodology that would be aimed at describing Kperm using the integrated laboratory studies, namely by adding rock to the analysis. As a result of statistical analysis, it was found that permeability in intervals with low reservoir properties was controlled with the same significance degree by both porosity and rock density for all lithological differences. At the same time, the presence of highly permeable reservoirs for sandstones and their practically absence for aleurolites were noted. For all lithological differences, relationships were established between the permeability coefficient not only with porosity, but also with rock density. The methodology for constructing statistical models for calculating permeability from the values of porosity and rock density was implemented separately for the fields of the eastern and western parts of the Babkinskaya anticline. The described approach to taking into account the influence of rock density on permeability made it possible to determine the differentiated influence of lithotypes on the filtration characteristics of the reservoir. When modeling a reservoir, it is necessary to move from linearity to nonlinearity and take into account that the problem of permeability distribution in the reservoir being solved is somewhat more complicated: in different areas, sometimes the permeability is not controlled by porosity in principle, but somewhere only this parameter prevails. The methodical approach was recommended for 3D modeling. Revealing the relationships between the parameters was most important when developing a methodology for tuning the model in the interwell space. The development of a reliable estimate of permeability for the vast majority of wells will significantly improve the efficiency of hydrodynamic modeling. At the same time, it is necessary to comprehensively take into account the identified relationships between the petrophysical characteristics of production layers. The use of the approach to the analysis of petrophysical characteristics will allow obtaining a more reliable and less subjective hydrodynamic model of the formation.

Estimation of Rock Characteristics Based on Polarization Spectra: Surface Roughness, Composition, and Density

Surface polarization characteristics provide crucial structural information of the Earth's surface. As two key elements of the natural geographical environment, rocks and soils play an important role in the study of surface processes. Inherent surface characteristics, such as surface roughness, composition, and density are critical parameters for the remote monitoring of land surfaces as they affect the polarization characteristics of scattered light waves. In this study, we investigated the relationship between surface roughness, composition, and density, and the polarization spectra of limestone-dolomite series rock. Results reveal a power function relationship between the surface roughness and the degree of polarization peaks among different detection zenith and azimuth angles. The depth and position of the absorbing waveband are significantly correlated with the characteristic component contents. The rock density was determined via the polarized reflection spectra, with the Earth's surface density calculations associated with a 2.6% divergence from the current recognized data. Our results demonstrate the ability of polarized spectra to retrieve surface roughness, composition, and density, with potential for further development in future work.

Fundamentals of Rock Physics

Rock physics encompasses practically all aspects of solid and fluid state physics. This book provides a unified presentation of the underlying physical principles of rock physics, covering elements of mineral physics, petrology and rock mechanics. After a short introduction on rocks and minerals, the subsequent chapters cover rock density, porosity, stress and strain relationships, permeability, poroelasticity, acoustics, conductivity, polarizability, magnetism, thermal properties and natural radioactivity. Each chapter includes problem sets and focus boxes with in-depth explanations of the physical and mathematical aspects of underlying processes. The book is also supplemented by online MATLAB exercises to help students apply their knowledge to numerically solve rock physics problems. Covering laboratory and field-based measurement methods, as well as theoretical models, this textbook is ideal for upper-level undergraduate and graduate courses in rock physics. It will also make a useful reference for researchers and professional scientists working in geoscience and petroleum engineering.

Rock Characterization Through Physical Properties and Their Relationship to Simple Compressive

This work proposes a simple methodology and practical application in the field for the approximate determination of the Unconfined Compressive Strength (UCS) in rocks, property or characteristic that is important in mining, since through it analyzes are carried out to the assessment of security and stability factors and/or possible fortification systems in the works or mining structures, in addition to the characterization of the UCS is also influential in the use of explosives for the exploitation or extraction of materials from a quarry or mine. This estimate is proposed based on the determination of the following three properties of the rock, which in this investigation we call density, porosity and absorption ‘in mine’. These physical properties can be obtained in a simple, but methodical way and in this work, tests have been carried out on the same material or rock from the Cojitambo area, Cañar province (Ecuador) and on the basis of 60 samples or test tubes. The results obtained allow a correlation between the properties described above and the UCS, in addition to a calculation methodology for the proposed objective. Keywords: compression, rock, density, porosity, absorption, fortification. Resumen En este trabajo se propone una metodología sencilla y de aplicación práctica en campo para la determinación aproximada de la Resistencia a la Compresión Simple (RCS) en rocas, propiedad o característica que es importante en minería, ya que mediante la misma, se ejecutan análisis para la valoración de factores de seguridad y estabilidad y/o posibles sistemas de fortificación en las obras o estructuras mineras, a más de que la caracterización de la RCS es también influyente en el uso de explosivos para la explotación o extracción de materiales de una cantera o mina. Esta estimación se la propone en base a la determinación de las siguientes tres propiedades de la roca, que en esta investigación las denominamos densidad, porosidad y absorción ‘en mina’. Estas propiedades físicas se las puede obtener de una forma simple, pero metódica y en este trabajo se han ejecutado ensayos sobre un mismo material o roca proveniente de la zona de Cojitambo, provincia del Cañar (Ecuador) y sobre una base de 60 muestras o probetas. Los resultados obtenidos permiten una correlación entre las propiedades antes descritas y la RCS, a más que se ha estructurado una metodología de cálculo para el objetivo planteado. Palabras Clave: compresión, roca, densidad, porosidad, absorción, fortificación.

Pervasive fluid-rock interaction in subducted oceanic crust revealed by oxygen isotope zoning in garnet

Dehydration reactions in the subducting slab liberate fluids causing major changes in rock density, volume and permeability. Although it is well known that the fluids can migrate and interact with the surrounding rocks, fluid pathways remain challenging to track and the consequences of fluid-rock interaction processes are often overlooked. In this study, we investigate pervasive fluid-rock interaction in a sequence of schists and mafic felses exposed in the Theodul Glacier Unit (TGU), Western Alps. This unit is embedded within metaophiolites of the Zermatt-Saas Zone and reached eclogite-facies conditions during Alpine convergence. Chemical mapping and in situ oxygen isotope analyses of garnet from the schists reveal a sharp chemical zoning between a xenomorphic core and a euhedral rim, associated to a drop of ~ 8‰ in δ18O. Thermodynamic and δ18O models show that the large amount of low δ18O H2O required to change the reactive bulk δ18O composition cannot be produced by dehydration of the mafic fels from the TGU only, and requires a large contribution of the surrounding serpentinites. The calculated time-integrated fluid flux across the TGU rocks is 1.1 × 105 cm3/cm2, which is above the open-system behaviour threshold and argues for pervasive fluid flow at kilometre-scale under high-pressure conditions. The transient rock volume variations caused by lawsonite breakdown is identified as a possible trigger for the pervasive fluid influx. The calculated schist permeability at eclogite-facies conditions (~ 2 × 10–20 m2) is comparable to the permeability determined experimentally for blueschist and serpentinites.

Valuable Cuttings-Based Petrophysic Analysis Successfully Reduces Drilling Risk in HPHT Formations

Cuttings data has always been neglected or forgotten as a source of information by many operators. In some areas, it is even common practice to throw away cuttings in order to reduce cost. However, cuttings data can yield a great amout of information to provide great value and support to drilling operations, as well as reduce potential downhole risks. This was evident in wells drilled in remote Western regions of China, where wells typically have high temperature high pressure (HTHP) formations with a true vertical depth ranging between 4000-7000 meters and target formation temperature between 150-160 degrees Celcius. Due to severe drilling conditions, the measurement tools of Logging While Drilling (LWD) and Measured While Drilling (MWD) are at high risk of running into holes. Even due to the high formations’ temperatures is over the bottom line of LWD and MWD tools, the sensors of LWD and MWD cannot work efficiently in such circumstances, increasing the drilling risk and expense. Thus, "blind" drilling is the most reasonable economical choice for local operators. Without sufficient real-time formations’ information, the drilling uncertainties dramatically increase. The fluid loss, pipe stuck, as well as drilling bit damages frequently occur. Currently, there is no successful well that accesses to the target reservoir. The data from the wireline logs and cores cannot be available, as the well is the first exploration well in the block; however, during drilling, only drill cuttings are available for peoples. The creative cutting-based petrophysics models are built for the formation analysis that is able to provide rock density, cuttings gamma, Delta Time of Compressional Acoustic (DTC), Unconfined Compressional Strength (UCS) Index, Caliper Index, Brittleness Index, and Hydrocarbon Index from the cuttings samples at the wellsite on a near-real-time basis. This data can help people quantitatively and qualitatively evaluate the downhole formations on a near-real-time basis and can help people to make a more reasonable decision, and therefore, reduce the drilling risk within a controlled level. The authors provide the several cases to study the cutting models into drilling events, and proves the models are consistent with log and core data, and match the drilling parameters and like ROP, and pumping pressure, as well as torque, and bit performance. LWD and MWD are unable to run into the hole due to high formation pressure and extreme risky hole. The field portable XRF instrument is applied, and the mineralogy and elements input into the models. The cuttings petrophysics analysis application can provide the valuable information for drilling engineers to drill the wells to TD.

Change in the Rock Pressure when Mining a Coal Seam with a Longwall Face

Development of the geomechanical processes is of great importance for human activity in the underground conditions. Coal mining is accompanied by displacement of the enclosing rocks, which requires a special approach to study of the geomechanical processes. In particular, this is due to an increase in the productivity of the excavation sections. Increase in the volume of the second working, the length of the longwalls and the size of the extraction pillars will transform all the geomechanical processes occurring in the face. Modern coal mining technologies are associated with certain specific features of the displacement of enclosing rocks, which necessitate the development of new approaches to the study of the geomechanical processes. The intensification of work inevitably leads to a change in the geomechanical environment in the vicinity of the face. The article discusses the methods and means of studying the process of rocks displacement as a result of construction of the mine workings. For example, a site is selected at the mine named after S.M. Kirov, long-face No. 24-62. Depth to the developed seam is from 476 to 520 m from the installation chamber. Average thickness of the seam is 2.5 m, length of the face is 300 m, length of the pillar is 2500 m. The average rate of advance is 10 m / day. Based on the monitoring of the rock pressure indicators on the mechanized support section, the wave-like nature of the rock pressure distribution in a long-face during mining of the extraction pillar was determined. The surface of the pressure domes was rebuilt using the Surfer software product, which allowed to track the processes in the face part of the longwall. Data on the pressure in the roof supports were used. In the calculations, the average rock density was assumed to be 2.5 m3/t. Since the surface of the pressure vaults makes it possible to judge the processes in the bottomhole of the mined seam, the height of the random collapse zone is determined from the pressure readings in the support struts. It is the one which presses on the powered support. Repetitive areas of the increased rock pressure were noted approximately every 200–250 m. Profiles of the surface of pressure arches along the length and in the long-face building cross are given. Considering the processes of structuring the rock mass, an algorithm for finding the height of the pressure arch was developed, which ensures a satisfactory convergence with the actual data.

Analysis of geological-geophysical materials and qualitative assessment of the oil and gas perspectives of the Yuzhno-Kharbizhinsky area (Northern Caucasus)

На современном этапе развитие нефтяной промышленности Российской Федерации невозможно без пополнения ресурсной базы и поэтому актуальной задачей является поиск новых методик оценки и анализа нефтегазоносности перспективных участков. Цель исследований: анализ емкостно-фильтрационных свойств пород коллекторов прикамского горизонта в пределах Южно-Харбижинского участка, с целью прогноза емкостно-фильтрационных параметров на участке Восточный. Методика исследований. Для выполнения анализа емкостно-фильтрационных и геолого-геофизических параметров пород коллекторов кумской свиты Южно-Харбижинского участка, были построены графики изменчивости емкостно-фильтрационных и геолого-геофизических параметров и проведен их корреляционный анализ. Для этого были использованы данные ГИС и данные лабораторных исследований коллекторов, полученные при бурении скважины №88-РД. Оценка коэффициента пористости, объемной плотности, минералогической плотности и плотности насыщенности пород определена на стадии оценки месторождений по методикам А.М. Нечая и Б.Ю. Вендельштейна, Н.В. Манчевой, базирующимся на комплексной интерпретации БК (БКЗ) – НГК и БК (БКЗ) – НГК – ПС. Результаты исследований. Значимой положительной корреляционной связью обладают следующие пары параметров: коэффициент пористости и удельное сопротивление пород, коэффициент пористости и относительное сопротивление пород, коэффициент пористости и объемная плотность, коэффициент пористости и плотность минералогическая, коэффициент пористости и плотность насыщенных пород, удельное сопротивление пород и относительное сопротивление пород, удельное сопротивление пород и объемная плотность, удельное сопротивление пород и плотность минералогическая, удельное сопротивление пород и плотность насыщенных пород, относительное сопротивление пород и объемная плотность, относительное сопротивление пород и плотность минералогическая, относительное сопротивление пород и плотность насыщенных пород, объемная плотность и плотность минералогическая, объемная плотность и плотность насыщенных пород, плотность минералогическая и плотность насыщенных пород. Наблюдается зависимость пористости от сопротивления, что указывает на наличие в породах коллектора углеводородов, т.е. с увеличением пористости увеличивается сопротивление, что также наблюдается на графиках.Изучив распределение показателей на Южно-Харбижинском участке по одному горизонту можно сделать вывод, что эти показатели различаются очень слабо, что свидетельствует об однородности свойств пласта. Качественные показатели остаются без изменения. На Восточном участке можно ожидать схожие показатели. Наличие промышленных скоплений углеводородного сырья оценивается как весьма вероятное At the present stage, the development of the oil industry of the Russian Federation is impossible without replenishing the resource base, and therefore an urgent task is to search for new methods for assessing and analyzing the oil and gas content of promising areas. Aim. Analysis of the reservoir-filtration properties of reservoir rocks of the Kama horizon within the Yuzhno-Kharbizhinsky area, in order to predict the reservoir-filtration parameters for the Vostochny area. Methods. To analyze the reservoir-filtration and geological-geophysical parameters of the reservoir rocks of the Kuma suite of the Yuzhno-Kharbizhinsky area, graphs of the variability of the reservoir-filtration and geological-geophysical parameters were constructed and their correlation analysis was carried out. For this, well logging data and data from laboratory studies of reservoirs obtained during drilling of well No. 88-RD were used. The estimation of the porosity coefficient, bulk density, mineralogical density and saturation density of rocks were determined at the stage of assessing deposits according to the methods of A.M. Nechaya and B.Yu. Wendelstein, N.V. Mancheva, based on a comprehensive interpretation of BK (BKZ) - NGK and BK (BKZ) - NGK - PS. Results. The following pairs of parameters have a significant positive correlation: porosity coefficient and resistivity of rocks, porosity coefficient and relative resistivity of rocks, porosity coefficient and bulk density, porosity coefficient and mineralogical density, porosity coefficient and density of saturated rocks, rock resistivity and relative rock resistance, rock resistivity and bulk density, rock resistivity and mineralogical density, rock resistivity and saturated rock density, rock relative resistivity and bulk density, rock relative resistivity and mineralogical density, rock relative resistivity and saturated rock density, bulk density and mineralogical density, bulk density and density of saturated rocks, mineralogical density and density of saturated rocks.A dependence of porosity on resistance is observed, which indicates the presence of hydrocarbons in the reservoir rocks, i.e. with an increase in porosity, resistance increases, which is also observed in the graphs.Having studied the distribution of indicators in the Yuzhno-Kharbizhinsky area along one horizon, it can be concluded that these indicators differ very slightly, which indicates the homogeneity of the reservoir properties. Qualitative indicators remain unchanged. Similar performance can be expected in the Eastern section. The presence of industrial accumulations of hydrocarbon raw materials is assessed as highly probable

Nanopore Formation and Structural Changes in Black Shale During the Initial Weathering Stage: A Longmaxi Formation Profile in Northwestern Hunan, China

Understanding the controls on composition changes and porosity evolution in the critical zone of shale remains a major challenge. The aim of the present study is to develop a model of the changes in mineral compositions, chemical compositions and nanopore formation in shale during the initial weathering stage. To understand these processes, we selected a Silurian shale profile rich in pyrite and organic matter located in South China. Based on X-ray diffraction (XRD) and bulk elemental data, the variations in mineralogical and chemical compositions with depth were studied. To characterize the full pore size spectrum and to gain insight into the nature of secondary pores and their relationship with weathering, nuclear magnetic resonance (NMR) measurements and petrographic observations were combined with scanning electron microscopy (SEM) imaging. The results show that Al and K are enriched slightly, while Ca and Na are depleted in the upper part of the weathering profile. Si, Mn and Ti are relatively stable from the bottom to the top of the profile. Quartz, feldspar, mica, illite and chlorite are the main minerals in the parent rock, and they are relatively stable along the profile. The rock density gradually decreases from 2.6 g/cm3 to 2.1 g/cm3 from the bottom to the top, and the color of the shales changes from black to grayish yellow, but no secondary minerals are detected. The chemical weathering of black shale is dominated by the oxidation of pyrite and organic matter, giving rise to color variation and nanopore formation. The increase in interparticle pores at the nanometer-micron scale is initiated by the dissolution of easily weathered components such as organic matter and pyrite. The removal of clay minerals and tiny particles by groundwater seepage may be the main cause of porosity enhancement during the initial weathering stage. This study suggests that nanoporosity may play an important role in the process of fluid-rock interaction within black shale during the initial weathering stage.