Shale is the dominant rock in the sedimentary record. The timedependent deformation is an inherent property of the dry rock as. Permeability refers to the capacity of a porous, sediment, soil or rock in this case to transmit a fluid. The rock mechanics of shear rupture in shale gas reservoirs is presented. Shale gas formations are unconventional reservoirs i. The different physical and mechanical properties of shale need to be quantified and standardized in. Although it can happen naturally, it is now used as a method to force oil and natural gas from shale. Why are brittleness and fracability not equivalent in designing.
Gas shale creep viscoelasticity in situ stress abstract laboratory testing of shale gas reservoir rocks reveal varying amounts of timedependent viscous deformation in response to applied differential stress. Summary unconventional resources such as shale gas are becoming increasingly important exploration, development, and production targets. Fracking simple english wikipedia, the free encyclopedia. Permeability refers to the capacity of a porous, sediment, soil or rock in this case to. We are aggressively expanding our global infrastructure to support new shale gas development outside of north america. The fundamental mechanics, physics and chemistry of shale behaviour remain poorly understood, partly due to neglect and partly due to less than ideal experimental conditions. Chinese journal of rock mechanics and engineering, v. Robert ressetar, utah geological survey, salt lake city, utah. This contrasts with a conventional gas reservoir produced from sands and carbonates such as. Understanding the controls on the elastic properties of reservoir rocks is crucial for exploration and successful production from hydrocarbon reservoirs. Work package 11 suggestions for policy formulation d11.
You may need a pdf reader to view some of the files on this page. Request pdf rock mechanics of shear rupture in shale gas reservoirs hydraulic fracturing is an effective technology to improve shale gas wells production. Pdf mechanics, physics, chemistry and shale rock properties. Results are compar ed and the more critical values, tha t is.
The color of shale can give a rudimentary visual indication to the strength of the rock, as it is generally noted that the lighter the color, the weaker the shale molinda 2003. In applied rock mechanics, students are provided with basic theory, laboratory demonstrations, handson exercises, and computer modeling demonstrations. Fluids water, magma, petroleum, natural gas, atmosphere. The success of shale gas recovery using hydraulic fracking is greatly dependent on the shale s brittleness, since brittle shales have many preexisting fractures. Dec 18, 2009 shale natural gas reserves are helping the 11 percent rise in natural gas production the united states has seen in the past two years. At present, shale gas plays a significant role in hydrocarbon reservoirs. Pressure characteristics and performance of multistage fractured. Courtesy of penn state marcellus center for outreach and research.
This lets gas and petroleum from source rocks get to reservoir rocks. Clearly applies rock mechanics to on and off shore oil and gas drilling. The integrated approach to understanding shale prospectivity involves, as a first step, conducting some core laboratory tests to relate and integrate the mineralogy, rock mechanics, and geomechanics. The success of shale gas recovery using hydraulic fracking is greatly dependent on the shales brittleness, since brittle shales have many preexisting fractures. Geomechanical analysis for deep shale gas exploration. Is it that new factors have appeared that we must take into account. Development, technology, and policy issues congressional research service 2 gas shale development takes place on both private and state lands. Joint sets in outcrops of the oil source rock, central sumatra basin. Shale natural gas reserves are helping the 11 percent rise in natural gas production the united states has seen in the past two years.
In europe, experience to date has been focused on low volume hydraulic fracturing in some conventional and tight gas reservoirs, mostly in vertical wells, and constituted only. Hydraulic fracturing in shale with h2o, co2 and n2 onepetro. To investigate the effects of shale bedding on crack behavior and fracturing mechanism, scanning electron microscope sem with a loading system was employed to carry out threepoint bending. An overview of hydraulic fracturing and other formation. A novel model of brittleness index for shale gas reservoirs. Hydraulic fracturing is generally employed in the exploration and exploitation of shale gas. Lee, 20, quantitative evaluation of completion techniques on influencing shale. The rise of shale gas development has triggered an intense public debate regarding the potential environmental and human health effects from hydraulic fracturing. Advances in theories, methods and applications for shale resource use shale is the dominant rock in the sedimentary record.
Data may provide field engineers with more knowledge about benefits and conveniences to guide their shale gas horizontal well completion plans. Timedependent deformation of shale gas reservoir rocks. Shale gas development involves aggressive hydraulic fracturing of a naturally fractured rock mass to generate an interconnected open fracture network with a large internal surface area for gas. Paleozoic shalegas resources utah geological survey. Shale gas development in the united states shale formations across the u. Xuan qin, dehua han, and luanxiao zhao, rock physics lab, university of houston. Petrophysics of unconventional reservoirs training course. Critical geomechanics concepts for hydraulic fracturing. The main difference between tight gas and shale gas, however, is that tight gas can be found in low permeability sedimentary rocks, such as sandstones, while shale gas rocks are usually impermeable 2 royal dutch shell plc. Shale gas exploration and production key issues and responsible business practices guidance note for financiers this guidance note has been produced to assist financial institutions in their internal conversations and decisionmaking with regard to risks and responsible business practices associated with shale gas production.
Pdf shale makes up about three fourths of drilled formations. But the deposits have been known about for decadeswhy are the. Proposal pdf well database xls bibliography of published stratigraphic definition, petrologic, rock mechanics, geochemical, and geochronology analysis pdf presentations pdf burial histories of mississippian potential source and shalegas reservoir rocks, central and western utah. Rock physics modeling of organicrich shales with different maturity levels. Advances in theories, methods and applications for shale resource use. Applied rock mechanics training course petroskills arm. Experimental investigation on mechanical and acoustic.
The critical taper model is a simple means of determining whether basic rock mechanics data e. Fracking, or hydraulic fracturing, is forcing fractures in a rock layer, by fluid that is put under pressure. We have developed an improved anisotropic rock physics model to incorporate toc effects, in addition to effects of mineralogy, porosity, and fluid content, on seismic and electrical properties of shale gas. In addition to a comprehensive manual, software is provided for the student to perform wellbore stability calculations. We explore the use of these gases as stimulants on green river shale to compare the form and behavior of fractures in shale driven by different gas compositions and states and indexed by breakdown. Investigations on the effects of confining pressure and burial depth on mechanical and acoustic parameters are significant for studying the deep shale deformation, failure rule, and hydraulic fracturing.
The method and theory do not require further rock mechanics parameters. Economic and efficient hydraulic fracturing, known as volume fracturing, is largely associated with formation characteristics, including anisotropy and brittleness in rocks. Although it can happen naturally, it is now used as a method to force oil and natural gas from shale history and method. Further research on the mechanical properties of rocks. Hydraulic fracturing is a mature completion technique which has been extensively applied in tight and unconventional gas reservoirs. Royalty rates, rents, and signing bonuses paid to state and private landowners vary. Numerical analysis of fracture propagation during hydraulic fracturing operations in shale gas systems pdf 11 pp, 3 mb. All three formations are composed of high proportion of quartz, low. The integrated approach to understanding shale prospectivity. Shale failure mechanics and intervention measures in.
The timedependent deformation is an inherent property of the dry rock as it occurs in the absence of pore. The rapid rise of shale gas development through horizontal drilling and high volume hydraulic fracturing has expanded the extraction of hydrocarbon resources in the u. Based on that we might ask ourselves why is the production of gas higher than expected. A comprehensive overview of the key geologic, geomechanical and engineering principles that govern the development of unconventional oil and gas reservoirs.
Critical geomechanics concepts for hydraulic fracturing and. In this study, we develop rock physics models to simulate the elastic properties of organicrich shales with different maturity levels. Response of rocks to applied loads earth materials rocks soils fluids. Shale and rock mechanics as applied to slopes, tunnels, mines and hydrocarbon extraction sponsored by speakers and debaters for further information on the shale symposium please contact. Shale gas development is considered unconventional when contrasted with conventional subterranean natural gas reservoirs. Interpret petrophysical data gathering from unconventional reservoirs from both core. The different physical and mechanical properties of shale need to be quantified and standardized in relation to the mine environment. The brittleness indices used in rock mechanics and their. Modern hydraulic fracturing technology involves sophisficated engineering. Here, we report on the mineralogy, lithofacies, petrophysics, and rock mechanics of samples collected from the ediacaran upper sinian, lower cambrian, and lower silurian black shale intervals. Pdf shale gas development involves aggressive hydraulic fracturing of a naturally. Pdf on mar 26, 20, qinghui li and others published rock mechanical properties of shale gas reservoir and their influences on hydraulic fracture find. Mechanical properties of three selected shale gas deposits.
Timedependent deformation of shale gas reservoir rocks and. This map shows what geologists believe the land looked like 385 million years ago during the middle devonian period with. Updated with new chapters on operations surrounding shale oil, shale gas, and hydraulic fracturing, and with new sections on in. The basic suite of core tests recommended by this work includes. Shale gas exploration and production key issues and. In texas, where similar gas shale development takes place, the rates are generally higher.
It is also the subject of increased interest because of the growing contribution of shale oil and gas to energy supplies, as well as the potential use of shale formations for carbon dioxide sequestration and nuclear waste storage. Updated with new chapters on operations surrounding shale oil, shale gas, and. The confining pressure is controlled by a manual high pressure generator using silicone. We studied the static and dynamic elastic properties of shale gas reservoir rocks from barnett, haynesville, eagle ford, and fort st.
The main focus of this thesis is to study the basic rock mechanical properties of shale gas reservoir rocks, the insitu state of stress in shale gas reservoirs, and. The standard as3980 is not part of our scope of accreditation. Slickwater fracturing is the most routine form of well stimulation in shales. Fracturing as a method to stimulate shallow, hard rock oil wells dates back to the. The existing shale fracture mechanics tests schmidt and huddle, 1977. Geoscientists involved with the evaluation and exploitation of unconventional reservoirs including tight gas sands, shale gas, and coalbed methane. The potential natural gas resource from shale gas is estimated between 14. The shale gasshale oil system is different from the conventional reservoirs cr mentioned above, since shales are part of a group known in the.
Experimental study on mechanical behavior and brittleness. This thesis presents five studies of a gas shale reservoir using diverse. Rock physics modeling of organicrich shales with different. Abstract the potential for shale gas development and hydraulic. The practical application of rock mechanics is emphasized. Journal of rock mechanics and geotechnical engineering. Shale gas potential of the major marine shale formations. Unconventional reservoirs conventional reservoirs extremely tight very tight tight low moderate high 0.
Covering hydrocarbonbearing formations, horizontal drilling, reservoir seismology and environmental impacts, this is an invaluable resource for geologists, geophysicists and reservoir. Rock brittleness has been considered an important geomechanics parameter in the. Pdf rock mechanical properties of shale gas reservoir and their. Rock mechanics of shear rupture in shale gas reservoirs. Shale specimens at six different depth levels ranging from 1535 to 1635 m have been collected from a shale gas well in southwest china. Geomechanics and flow parameters that influence shale gas.
Central texas as one model for thermogenic shale gas assessment, in r. The book breaks down the mechanics of shale gas reservoirs and the use of mathematical models to. Rock mechanicsgeomechanics symposium, minneapolis, mn. Tables 1 and 2 provide a summary of the data used to establish the geomechanics model.
Shale gas is the term often used to describe both tight gas and shale gas resources. But some of it remained locked in the tight, low permeability shale layers, becoming shale gas. Our rock mechanics laboratory has specialised capability to conduct low frequency acoustic measurements. When analyzing the flow production data in a shale play notice that these measures are higher than those predicted by darcys law with which they were calculated. The growth of unconventional oil and gas developments has accelerated this trend because the need to hydraulically fracture reservoir. The process involves the highpressure injection of fracking fluid primarily. Linear elastic fracture mechanics characterization of an. The laboratory measurements are also used to inform and validate rock physics models developed by the csiro geophysics team. Drilling operations and well design, second edition, keeps petroleum and drilling engineers centrally focused on the basic fundamentals surrounding geomechanics, while also keeping them uptospeed on the latest issues and practical problems. This book, volume 66 presents tactics and discussions that are urgently needed by the petroleum community regarding unconventional oil and gas resources development and production.
Are these still fulfilling classical laws of fluid mechanics used in. Improved rockphysics model for shale gas reservoirs. In view of efficient stimulation of tight shale gas reservoirs, it is unclear. Mechanical properties of shalegas reservoir rocks part. Hydraulic fracturing is a well stimulation technique involving the fracturing of bedrock formations by a pressurized liquid. The mechanical properties and fracturing mechanism of shale containing beddings are critically important in shale gas exploitation and wellbore stability. For unconventional reservoirs such as shale with extremely low permeability, long horizontal laterals with multistaged hydraulic fractures are necessary to deliver economic production. However, geophysical characterization of these unconventional reservoirs remains challenging because of limited understanding of geophysical responses to reservoir properties such as total organic carbon toc. S is found in barnett shale, haynesvillebossier shale, antrim shale, fayette. Our rock mechanics laboratory has specialised capability to. The marine black shale formations on the upper yangtze platform, south china, are currently exploration targets for shale gas.