Or15066 induced versus natural fractures earthwise. Porepressure buildup and effects on seismic velocities, journal of applied geophysics on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. In any case, the results to date have provided a template for exploration which may prove invaluable in the future when transportation infrastructure and financial terms improve and energy markets are developed. The degree to which hydrocarbon generation processes have advanced in a given source rock can be recognized on the basis of elemental analysis of kerogens hcoc diagrams, as well as by analysis of yield and composition of. Discovery of cryogenian interglacial source rocks in the. The draupne formation, a world class source rock, which stretches over a broad range of depths and maturity.
Implications for hydrocarbon generation and primary migration. Sonnenberg department of geology and geological engineering colorado school of mines sarah k. Rock eval pyrolysis results show that taratu formation accommodates organic matter of excellent quantity and. There are only a limited number of the rocks with the steeper western slope of the upper arch. Sedimentation in areas of high organic productivity 2. Regions of rock containing microcracks near coalesced macroscale fractures can behave differently than the original matrix material due to the permanent structural changes. Source rock coal seam vitrinite reflectance organic geochemistry. Heterogeneity is an inherent component of rock and may be present in different forms including mineral heterogeneity, geometrical heterogeneity, weak grain boundaries and microdefects. Quantitative mineralogy and mi crofractures in the middle bakken formation, williston basin, north dakota stephen a. Pdf microfracturing during primary migration in shales. The source northern west siberia, and has very large hydrocarbon reserves can be approximated by the asymmetric lens of basic salmanov et al. By continuing to use our website, you are agreeing to our privacy policy.
I consider illite transversely isotropic, the kerogenoilwater. Promoted by the increasingly growing energy demand and successful shalegas development in north america,china has also made a series of progresses in shale gas exploration and evaluation. Hydrocarbon generation induced microcracking of source rocks and its seismic detection. Ultrasonic velocity and anisotropy of hydrocarbon source. Fracture patterns and their origin in the upper devonian antrim shale gas reservoir of the michigan basin. Appleby advanced mineralogy research center colorado school of mines j. Jesse havens and michael batzle department of geophysics. Apr 24, 2017 the preferred orientation of clay minerals dominates the intrinsic anisotropy of shale. Anisotropy measurements derived from multicomponent data may prove useful in identifying mature source rocks vernik, 1992. Western siberia hydrocarbon exploration spectral density. Burial history and catalytic effects, due to source rock matrix chemistry, affect the rate of generation, although these effects are secondary to the kinetic effects figure 1 shows hydrocarbon generation vs. Jesse havens and michael batzle department of geophysics summary ultrasonic velocities and static moduli have been measured on four samples from the middle bakken and one sample from the upperbounding lodgepole limestone for the purpose of calculating the minimum horizontal stress.
John, in your article you touch upon a very interesting aspect of learning in that if the concepts of science that we practice are explained in a simple. Vernik l 1994 hydrocarbon generation induced microcracking of source rocks geophysics 59 55563 crossref vernik l and landis c 1996 elastic anisotropy of source rocks. The preferred orientation of clay minerals dominates the intrinsic anisotropy of shale. No evidence of vertical microcracks induced by petroleum generation and filled with pure bitu men was petrographically observed by lewan. Orthotropic inversion uses azimuthally sectored seismic data stacked, based on incident angle ranges. Petroleum source rocks characterization and hydrocarbon.
Pdf geomechanical analysis of maturation for the draupne. Although the effect of pressure is well recognized, the effect of pulse duration indicates that the ultimate fragmentation increases with the time of application of a plane wave pulse. If the address matches an existing account you will receive an email with instructions to reset your password. Hydrocarbon generation modeling and source rock characterization have been carried out on rock samples of the taratu formation in the great south basin, new zealand. Two of these investigate the fundamental behaviour of microcracking in the laboratory. Seismic data conditioning for avoaz analysis case study from a north kuwait unconventional reservoir. In this study petrographic observations, rock eval and total organic carbon content toc data, and logderived physical properties were analyzed in order to evaluate eventual. Earlier formation of horizontal microcracks has also been demonstrated in tight. We also examine the effects of crack spacing and source rock temperature on subcritical crack propagation. Chapter 3 generation and expulsion of hydrocarbons sciencedirect. Microcracking in rock as acoustic emission tsuyoshi.
Rick sarg department of geology and geological engineering. Hydrocarbongenerationinduced microcracking of source rocks. Models constructed incorporate organic nanopores filled with hydrocarbons, and the alteration of the remaining kerogen solids. Do electromagnetic pulses induce the relaxation or. Fred schroeder, retired from exxonexxonmobil presented on july, 2017. Petrophysical implications of source rock microfracturing.
Accurate avoaz analysis requires proper data processing. In clastic rock, the grains may be rotatd by neighbor grains, forming cracks in the cement or along the grain boundary. Source rocks for hydrocarbon generation incorporated. Continental organicrich shale occurs extensively in the major petroliferous basins of china since mesozoic,discussion about shalegas potential in the shale has special theoretic and practical. Static and dynamic properties of the bakken jesse havens and. The present work describes a multiphysics model to investigate subcritical propagation of initially oilfilled, subhorizontal collinear microcracks driven by the excess pressure induced by the conversion of oil to gas in a petroleum source rock under continuous burial. Static and dynamic properties of the bakken jesse havens. Aug 01, 2011 read kerogen to oil conversion in source rocks. Modelling petroleum migration through microcrack propagation in. Rock strength variation is closely related to its microstructure.
Areas underlain by thermally mature generative source rocks in a sedimentary basin are called generative basins or depressions or else hydrocarbon kitchens. U1663207, and the national natural science foundation of china no. Shale diagenesis and hydrocarbon generation in shales has a direct relationship with the evolution of the mechanics of maturation. Jan 01, 2010 read subcritical propagation and coalescence of oil. Hence, source rock anisotropy and simultaneous generation of oil and gas. Avo effects of a hydrocarbon sourcerock layer porosity. Understanding the changes in the elastic and transport properties of organicrich marl upon maturation is a key to developing rock physics models for reservoir characterization. The draupne formation, a world class source rock, which stretches over a broad range of depths and maturity, provides the ideal candidate to study the interplay between maturation and geomechanical parameters. Microcracks induced by the excess oilgas pressure may propagate and form. Since the source rock has a layered structure, the best forward model is a transversely isotropic layer between two isotropic halfspaces, parameterized by the layer thickness and the amount of organic material. The degree of microcracking can vary depending on fluid, rock type, stresstemperature boundary conditions, as well as inherent material properties and heterogeneities.
Hydrocarbon generation an overview sciencedirect topics. Pdf avo effects of a hydrocarbon sourcerock layer researchgate. Estimating the petroleum expulsion behaviour of source rocks. Petrography can also determine the amount of microcracking, which may not be visible in a field survey but can be critical to performance and durability. Hydrocarbon generation induced microfracturing in source rocks is important. Rock stress and rock damaging are some of the main obstacles encountered when designing and constructing engineering projects with rock. Automated source edge location with a new variable passband horizontalgradient operator. Elastic properties of organic rich mudrocks are modeled as a function of thermal maturation. An interview with john logel february 2014 cseg recorder. The source rock is described by a porous transversely isotropic medium composed of illitesmectite and organic matter. To investigate primary petroleum migration through microfracturing of source rocks, we develop a theoretical multiphysics model incorporating simultaneous generation of oil and gas from kerogen, elastic anisotropy of the source rock and propagation of microcracks filled with oil and gas.
Mcroc a model to estimate timedependent microcracking. G580016zskfzy002, the nsfc and sinopec joint key project no. The depth of hydrocarbon generation and the yield of individual hydrocarbon phases are primarily a function of the kinetics of the kerogenhydrocarbon conversion. Fracturing controlled primary migration of hydrocarbon. Stress and timedependent failure of brittle rocks under. In all calculations, we assume that the shale source rocks are impermeable and have the following properties. The organic content of petroleum sourcerock layers can be determined from seismic data with a suitable avo technique. Anisotropy rock physics model for the longmaxi shale gas. Quantitative mineralogy and microfractures in the middle. The mechanics can then be related to the stress field in the rock mass, or can be compared to results from dynamic micromechanical models. Creation of porosity has been reported by goff 1983, who analyzed the hydrocarbon generation and migration from jurassic source rocks of northsea basins, in particular he obtained the change in porosity during maturation of the kimmeridge clay source rock, with 30% oil expulsion his table 7, and showed that the total porosity at first decreases as water is expelled from the rock, but then increases. The crack propagation distance, propagation duration, crack coalescence and excess pressure in the crack are determined.
Widespread beddingparallel veins of fibrous calcite beef in a mature source rock vaca muerta fm, neuquen basin, argentina. An analysis of horizontal microcracking during catagenesis. Petroleum source rock is defined as the finegrained sediment with sufficient amount of organic matter, which can generate and release enough hydrocarbons to form a commercial accumulation of oil or gas 1. Fracturing controlled primary migration of hydrocarbon fluids during. This chapter overviews the petroleum source rocks characterization and hydrocarbon generation, based on organic geochemical characteristics e. An overview of the possible definitions of damage variable describing the process of damage development on the basis of various hypotheses has been presented in the first part of the article. Microcracks are usually observed in crystalline rocks in two forms. The physics and efficiency of petroleum expulsion from coal. Microcracks originate within kerogen or at kerogenillite interfaces when pore pressure exceeds the beddingnormal total stress by only a few mpa due to the. Generation of hydrocarbons in source rocks is controlled by their temperature history with burial, as well as by quantity, type and structure of their kerogens.
The rock has a very low permeability and porepressure buildup occurs. The article is based on the results of uniaxial and triaxial compression tests, performed on wustenzeller sandstone. Even for highfold acquisition, this azimuthangle grouping can result in lowfold angle stacks. These source rocks formed in the lower tereeken fm. Then, we perform the inversion of cl and the thomsen anisotropy parameters. Read subcritical propagation and coalescence of oil. Geomechanical analysis of maturation for the draupne shale. Thermally induced microcracking refers to microcrack formation due to thermal effects. Hydrocarbon leakage interpreted on seismic data, marine. Permeabilityporosity relationships in rocks subjected to. Since the source rock has a layered structure, the best forward model is a. Hydrocarbon generation induced microcracking of source rocks. Geological society london special publications 59,1991.
Relevance of rock pressure measurements, in north atlanticgeology and continental drift. This paper focuses on the leakage processes taking place above a hydrocarbonfilled trap and how. This book will provide a basis to interpret acoustic emission ae as damage processes in stressed rock, with applications to stress measurements, size effects, source mechanisms, and fracture mechanics. Generation of hydrocarbons in source rocks springerlink. Feasibility of theoretical formulas on the anisotropy of. This report describes a model mcroc devised to estimate the extent of microcracking and consequent changes in rock elastic modulus and permeability. The organic content of petroleum source rock layers can be determined from seismic data with a suitable avo technique. A novel quantitative approachmenland w a,fleel a j,eds. Monitoring the changes in elastic and transport properties of. The source rock is the first of the essential elements necessary for hydrocarbon generation. A compressional wave seismic model for the ashrafi1 well. Modelling petroleum migration through microcrack propagation. Citeseerx document details isaac councill, lee giles, pradeep teregowda. Petrophysical implications of source rock microfracturing request.
Vernik l 1994 hydrocarbongenerationinduced microcracking of source rocks geophysics 59 55563 crossref vernik l and landis c 1996 elastic anisotropy of source rocks. From microstructural evidence, it was determined that, whereas microcracking controlled precompaction at room temperature, pressure solution was the main mechanism during. The work is devoted to the problem of role of ambient factors external electromagnetic field, in particular in the process of ageing of mechanically burden nonmetallic solids rocks. John, in your article you touch upon a very interesting aspect of learning in that if the concepts of science that we practice are explained in a simple way, they can be grasped easily by the listeners. Fdem simulation of rocks with microstructure generated by. The model is discussed in detail and is illustrated by various calculations pertinent to a vault designed to accept canadian nuclear fuel waste. Mapping those regional oil and gas generative hydrocarbon kitchens is feasible by integrating the existing source rock data into seismic depth maps that structurally follow the source horizons. Two mixing procedures for rock components were tested. The direct measurement of anisotropy is difficult because of the. However, the evolution of permeability and porosity in rocks can be constrained provided that the processes changing the pore space are known. Source rocks are commonly shales and lime mudstones. Hydrocarbon generation induced microfracturing in source rocks is important affecting both primary migration of hydrocarbons, and unconventional shale plays.
The research is supported by the foundation of state key laboratory of shale oil and gas enrichment mechanisms and effective development no. This lesson introduces the concept of source rocks for hydrocarbons, where organic material is contained and cooked over time with proper temperature and pressure conditions. Microcrack damage observations near coalesced fractures. We introduce the clay lamination cl parameter to the backus averaging method to describe the intrinsic shale anisotropy induced by the alignment of clay minerals. Characterizing the influence of stressinduced microcracks.
With the development of computer technology, the numerical model of rocks can be constructed via computer programming, and the numerical simulation avoids a mass of redundant experimental tests and usually limited by the samples retrieved from the subsurfaces. At high pulse durations, both the degree of fragmentation and microcracking are more. Gasdriven subcritical crack propagation during the conversion of oil. A specific research point is the effect of temporary activation of acoustic emission ae of rocks specimens during action. Jan, 2010 we also examine the effects of crack spacing and source rock temperature on subcritical crack propagation. Thermal maturation effects on the elastic properties of. Reservoir characteristics and potential evaluation of. The aim of this work is to obtain a model for source rocks relating to kerogenoil conversion and pore pressure to seismic velocity and anisotropy. Petroleum phase state prediction in deep reservoir of tashen. Psquantitative mineralogy and microfractures in the middle bakken formation, williston basin, north dakota stephen a. The source rock input parameters usually consist of the total organic carbon toc as a measure of the total organic matter, the rock eval s2 or hydrogen index hi as a measure of the amount of hydrocarbon that can be generated with respect to the toc, and the kerogen types to define the appropriate kinetic parameters to be used. In this paper, we employ ift to predict the shortterm strengths of hard rocks under compression and compare these results with experimental observations for granites deformed. The deposition of these rocks was accompanied by microbiotic recovery and inputs such as algae and bacteria at.
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