Core Analysis Methods Research Articles

Validation of the dynamic simulation capabilities of Serpent2/Subchanflow using experimental data from the research reactor SPERT IV D-12/25

Research nuclear reactors are critical to the development of nuclear technology, but because of the complex configuration of the fuel assemblies and the different initial operating conditions, neutronic and thermal–hydraulic analyzes are performed with dedicated or adapted codes. These simulation tools might not be as accurate, since they use simple resolution methods and assumptions that do not always capture all aspects of the behavior of a nuclear research reactor. On the other hand, as time goes by, the evolution of numerical tools for the core analysis of power reactors have experienced a considerable progress. Nowadays, pin/subchannel level analysis of the core with coupled codes based on transport (SP3, MOC, SN, etc.) or Monte Carlo methods are applied in addition to the nodal diffusion codes. Hence, the research community is adapting and validating selected high-fidelity tools developed for power reactors to perform detail core analysis of e.g. Material Testing Reactors (MTR) cores at plate and subchannel level.This work deals with the validation of the high-fidelity coupled Serpent2/Subchanflow, which was modified and extended for the plate/subchannel analysis of MTR-cores, using the data of rod ejection tests performed in the SPERT IV D-12/25 reactor, especially the tests B-34 and B-35 were selected to validate the dynamic capability of Serpent2/Subchanflow. In these unique tests, experimental data e.g. thermal neutron flux, core power evolution during the rod ejection tests, and the plate cladding temperature was measured. It is noted that, due to the lack of detailed information on the initial conditions, the extraction and introduction scenarios of the transient rod for the reactivity insertion required calibrations and assumptions regarding velocity and position.The comparison of selected parameters predicted by the coupled simulations at plate/subchannel level of the SPERT IV reactor with the measured data at static and transient conditions shows excellent agreement confirming the high accuracy appropriateness of the used code for the analysis of research reactors. The calculated values of thermal neutron flux and core power evolution have a statistical error of ± 2 sigma. It was also found that the maximum temperature difference between calculated and experimental values is 7 °C and ∼ 10 °C for tests B-34 and B-35, respectively. In addition, the coupled code predicts for the first time the temperature of each plate and subchannel considering the local feedbacks between neutronics and thermal-hydraulics allowing the identification of the hottest/coldest plate in the core. The high-fidelity validation tool can provide comparison solutions for current research reactor core analysis methods, such as core analysis with point kinetics or 3D nodal diffusion codes coupled with fuel assembly-level thermal-hydraulics.

A multidisciplinary approach to facies evaluation at regional level using well log analysis, machine learning, and statistical methods

Geological facies evaluation is crucial for the exploration and development of hydrocarbon reservoirs. To achieve accurate predictions of litho-facies in wells, a multidisciplinary approach using well log analysis, machine learning, and statistical methods was proposed for the Lower Indus Basin. The study utilized five supervised machine learning techniques, including Random Forest (FR), Support Vector Machine (SVM), Artificial Neural Network (ANN), Extreme Gradient Boosting (XGB), and Multilayer Perceptron (MLP), to analyse gamma ray, resistivity, density, neutron porosity, acoustic, and photoelectric factor logs. The Concentration-Number (C-N) fractal model approach and log–log plots were also used to define geothermal features. In a study on machine learning models for classifying different rock types in the Sawan field of the Southern Indus Basin, it was discovered that sand (fine, medium and coarse) facies were most accurately classified (87–94%), followed by shale (70–85%) and siltstone facies (65–79%). The accuracy of the machine learning models was assessed using various statistical metrics, such as precision, recall, F1 score, and ROC curve. The study found that all five machine learning methods successfully predicted different litho-facies in the Lower Indus Basin. In particular, sand facies were most accurately classified, followed by shale and siltstone facies. The multilayer perceptron method performed the best overall. This multidisciplinary approach has the potential to save time and costs associated with traditional core analysis methods and enhance the efficiency of hydrocarbon exploration and development.

The Concept of Soul Education With ‘Tazkiyatun Nafs’ According Imam Al-Ghazali and Ibn Qayyim Al-Jauziyyah

Today, there are often irregularities in the educational process. This is due to a lack of attention on the issue of the planting of morals and character of students, which focuses only on physical and intellectual education regardless of the education of students. Therefore, researchers are interested in researching more about moral education known as Tazkiyatun Nafs . The researcher utilized the concept of Imam Al Ghazali & Ibn Qayyim Al Jauziyyah by analyzing the similarities and differences between the two. The type of research is library research. The main data of this study was the book of Ihya' Ulumuddin & Ar-Ruh. The data obtained is by using the documented method. While in its analysis researcher use descriptive methods, comparative methods, and core or content analysis methods. According to Imam Al Ghazali , Tazkiyatun Nafs is an effort to improve morality and mental medicine and animate life with Islamic values. Then, according to Ibn Qayyim al-Jauziyah , Tazkiyatun Nafs is purifying himself by infusing a good ubudiyah with ta'dib . The two figures share the same understanding of the concept of Tazkiyah as an attempt to draw closer to Allah Almighty and the need to plant ta'dib in each teaching process by example in education. The differences between the two include the application of the Tazkiyatun Nafs method; Imam Al Ghazali emphasized three aspects namely Tathahhur, Tahaqquq, and Takhalluk . And Ibn Qayyim al-Jauziyyah emphasized the three different; Al Ilm, Riyadhah , and Takhalluk.

Permeability measurements using rate-transient analysis (RTA): Comparison with different experimental approaches

Reservoir engineers commonly apply rate-transient analysis (RTA) and pressure-transient analysis (PTA) methods to analyze multi-fracture horizontal wells (MFHWs) completed in unconventional reservoirs quantitatively for reservoir and hydraulic fracture properties. Data from core analysis techniques are commonly used to provide important input for RTA-PTA models. However, conventional laboratory techniques (i.e., steady-state and non-steady-state fluid flow) do not reproduce the operating conditions that MFHWs are subjected to in the field. In the current work, laboratory techniques that better reproduce these boundary conditions are explored and compared to more traditional core analysis methods.For this study, RTA methods are applied to gas produced from core plugs and PTA methods are applied to gas injection-fall-off data at the start of the core test before gas production. While the RTA method has been previously described by the authors, the application of the PTA method to provide an early, and fast, estimate of permeability is unique to this study. Further, our previous experimental setup for performing RTA was modified to accommodate not only the use of both RTA/PTA methods, but also the use of conventional core analysis methods (steady-state and non-steady-state methods) to allow for direct comparison of all methods.For both RTA and PTA core tests, the observed flow-regime sequence is transient linear flow followed by boundary-dominated flow, which is the same sequence that is commonly observed in the field for MFHWs producing from low-permeability and shale reservoirs. Two independent permeability values were estimated using the slope of the square root time plot and the time at the end of linear flow for each test. The pore volume of the samples were also estimated using the RTA method. Permeability and pore volume values obtained from the RTA method, referred to as ‘RTAPK’ previously, were in good agreement with those obtained from more conventional core testing methods (average coefficient of variation = 8%). The derived permeabilities from the time at the end of linear flow during the fall-off test were close to other permeabilities. In contrast, the square root time plot (fall-off) resulted in significantly higher permeabilities attributed to the experimental artifact caused by substantial dead volume in the injection port. The primary advantage of the RTA core analysis method is the accelerated test-time. For samples with permeability values ranging between 0.1 and 3 mD, the apparent gas permeabilities can be estimated in less than 3 to 10 minutes using both fall-off and production data.

Quantitative study of different patterns of microscale residual water and their effect on gas permeability through digital core analysis

Residual water significantly influences the permeability and recovery of low-permeability reservoirs. In this study, we evaluated the effect of different residual water clusters on gas permeability in low-permeability sandstone by using the X-ray computed tomography technique, digital core analysis and different numerical methods (i.e., the finite difference method (FD), lattice Boltzmann method (LBM), and Kozeny-Carman method (KC)). The residual water distribution patterns are classified into water film, isolated water and branch water by the sphericity index and Euler number, and these two parameters can respectively characterize the shape and the connectivity of the residual water clusters. The water film significantly influences the gas permeability, while the influence of branch water and isolated water on permeability is observed to be insignificant. The difference in gas permeability values influenced by branch water and isolated water is minimal. The FD and KC equation express the average properties of the study space, which will result in the permeability to be insensitive to the space structure affected by the different residual water clusters. The LBM is appropriate to simulate the microscopic flow with complex boundary conditions, and is recommended to evaluate the permeability affected by the different residual water clusters in microscale, because of its sensitivity to the change of space structure.

Experimental and Statistical Investigation of Reservoir Properties with the Effect of Waterflooding Treatment.

An oilfield reservoir over long-term operation may have different petrophysical information, which has a significant impact on oilfield maintenance and finance. Successful oilfield enhanced oil recovery benefits a lot from identifying and analyzing the variations of the critical properties after long-term waterflooding treatments. Since the inspection wells drilled within different development periods contain the core samples that have the petrophysical information at that period, it is necessary to collect and test the samples from different periods to investigate the overall tendency of the petrophysical properties. The samples from four inspection wells, which were drilled in four stages since the very beginning of development, were subjected to in-laboratory core analysis methods to illustrate the variation of some critical parameters in the reservoir. The permeability and porosity variation are revealed clearly by the experimental results. The migration and dissolution of clay minerals play a crucial role in the variation of petrophysical information and pore structure. To quantify the variations above, we applied the multiple linear regression model into our investigation. The dependent variable and all of the predictors in the model come from the experimental results. The quantitative results show the closed correlation between different parameters in the formation. With the development stage moving forward, the weight coefficients for different predictors have multiple trends. The experimental and statistical approach provides a novel understanding of the reservoir properties with the effect of waterflooding treatment

Coupled land surface–subsurface hydrogeophysical inverse modeling to estimate soil organic carbon content and explore associated hydrological and thermal dynamics in the Arctic tundra

Abstract. Quantitative characterization of soil organic carbon (OC) content is essential due to its significant impacts on surface–subsurface hydrological–thermal processes and microbial decomposition of OC, which both in turn are important for predicting carbon–climate feedbacks. While such quantification is particularly important in the vulnerable organic-rich Arctic region, it is challenging to achieve due to the general limitations of conventional core sampling and analysis methods, and to the extremely dynamic nature of hydrological–thermal processes associated with annual freeze–thaw events. In this study, we develop and test an inversion scheme that can flexibly use single or multiple datasets – including soil liquid water content, temperature and electrical resistivity tomography (ERT) data – to estimate the vertical distribution of OC content. Our approach relies on the fact that OC content strongly influences soil hydrological–thermal parameters and, therefore, indirectly controls the spatiotemporal dynamics of soil liquid water content, temperature and their correlated electrical resistivity. We employ the Community Land Model to simulate nonisothermal surface–subsurface hydrological dynamics from the bedrock to the top of canopy, with consideration of land surface processes (e.g., solar radiation balance, evapotranspiration, snow accumulation and melting) and ice–liquid water phase transitions. For inversion, we combine a deterministic and an adaptive Markov chain Monte Carlo (MCMC) optimization algorithm to estimate a posteriori distributions of desired model parameters. For hydrological–thermal-to-geophysical variable transformation, the simulated subsurface temperature, liquid water content and ice content are explicitly linked to soil electrical resistivity via petrophysical and geophysical models. We validate the developed scheme using different numerical experiments and evaluate the influence of measurement errors and benefit of joint inversion on the estimation of OC and other parameters. We also quantify the propagation of uncertainty from the estimated parameters to prediction of hydrological–thermal responses. We find that, compared to inversion of single dataset (temperature, liquid water content or apparent resistivity), joint inversion of these datasets significantly reduces parameter uncertainty. We find that the joint inversion approach is able to estimate OC and sand content within the shallow active layer (top 0.3 m of soil) with high reliability. Due to the small variations of temperature and moisture within the shallow permafrost (here at about 0.6 m depth), the approach is unable to estimate OC with confidence. However, if the soil porosity is functionally related to the OC and mineral content, which is often observed in organic-rich Arctic soil, the uncertainty of OC estimate at this depth remarkably decreases. Our study documents the value of the new surface–subsurface, deterministic–stochastic inversion approach, as well as the benefit of including multiple types of data to estimate OC and associated hydrological–thermal dynamics.

Core Design and Analysis of Axially Heterogeneous Boiling Water Reactor for Burning Transuranium Elements

The resource-renewable boiling water reactor (RBWR) is an innovative boiling water reactor that has the capability to breed or to burn transuranium elements (TRUs). Core characteristics of the RBWR of the TRU burner type were evaluated by two different core analysis methods. The RBWR core features an axially heterogeneous configuration, which consists of an internal blanket region between two seed regions, to achieve the TRU multi-recycling capability while maintaining a negative void reactivity coefficient. Axial power distribution of the TRU burner core tends to be more heterogeneous because the isotopic composition ratio of fertile TRUs to fissile TRUs becomes larger in the TRU burner–type core than in the breeder-type core and the seed regions need to be axially shorter than that of the breeder-type core. Thus core analysis of the TRU burner–type core is more challenging. A conventional diffusion calculation using nuclear constants prepared by two-dimensional lattice calculations was performed by Hitachi, while the calculation using nuclear constants prepared by three-dimensional calculations and axial discontinuity factors was performed by the University of Michigan to provide a more sophisticated treatment of the axial heterogeneity. Both calculations predicted similar axial power distributions except in the region near the boundary between fuel and plenum. Both calculations also predicted negative void reactivity coefficients throughout the operating cycle. Safety analysis was performed by Massachusetts Institute of Technology for the all-pump trip accident, which was identified as the limiting accident for the RBWR design. The analysis showed the peak cladding temperature remains below the safety limit. Detailed fuel cycle analysis by University of California, Berkeley, showed that per electrical power generated, the RBWR is capable of incinerating TRUs at about twice the rate at which they are produced in typical pressurized water reactors.

Advanced methods for the evaluation of a hybrid-type unconventional play: The Bakken petroleum system

Hybrid-type plays such as the Bakken petroleum system (BPS) can be particularly challenging from an interpretation, completion, or production perspective due to the mix of conventional and unconventional elements coexisting within a relatively short depth interval. In the BPS, conventional aspects include the presence of separate reservoir intervals, which, depending on your location within the basin, may include the Scallion, Middle Bakken, Sanish, and Three Forks. Unconventional aspects include the Lower Bakken and Upper Bakken shales, which are organic-rich shales comprising source rock and reservoir. Developing an accurate petrophysical evaluation of these formations requires a priori knowledge of the mineralogy, fluids, and geomechanical properties such that appropriate logging measurements, core analysis methods, and interpretation techniques can be obtained and used. During the development phase of an oil field, the log and core measurements being acquired and the petrophysical evaluation being performed may vary significantly from well to well across the field. Some wells may have triple-combo wireline or logging-while-drilling measurements consisting of bulk density, neutron porosity, and induction or laterolog resistivity, supplemented with a total gamma ray measurement. Borehole sonic logs may also have been acquired in some wells primarily for seismic calibration, geomechanical modeling, and hydraulic stimulation design. If the “standard” suite of measurements and petrophysical evaluation being provided fail to accurately represent the true complexity of the formations being evaluated, the asset valuation will, in most cases, be negatively impacted. Our formation evaluation of the BPS led to the identification of unique petrophysical challenges for each of the formations comprising the BPS. Traditional formation evaluation methods were applied to the BPS based on triple-combo measurements, a traditional petrophysical analysis, and the evaluation of net feet of pay. Advanced evaluation methods and techniques were then applied to address the petrophysical complexities identified with core evaluation, advanced log measurements, and discrepancies between the two. New petrophysical models were developed and fine-tuned to address the shortcomings of the simple models, and the net feet of pay were reevaluated using these new models. The detailed formation evaluation program used to characterize the BPS consisted of standard triple-combo logs supplemented with advanced downhole measurements including: (1) triaxial resistivity for thin-bed analysis, (2) nuclear magnetic resonance for porosity, free-fluid, and kerogen identification, (3) dielectric dispersion for water saturation, (4) geochemical spectroscopy for mineralogy and total organic carbon, and (5) dipole sonic for dynamic rock properties. Petrophysical models were developed using deterministic and probabilistic methods to integrate the measurements acquired for the most accurate analysis of porosity, saturation, and mineralogy and to best describe the hydrocarbon production potential of the BPS.

Crushed-Rock Vs. Full-Diameter Core Samples for Water-Saturation Determination in a Tight-Gas Siltstone Play

SummaryThe efficacy of crushed-rock samples vs. small plugs or full-diameter core samples for measurement of porosity, permeability, and fluid saturation is an important consideration in the evaluation of tight-gas reservoirs and shale-gas reservoirs. Crushed-rock core analysis methods originally developed for shale reservoirs are now, in some cases, being extended to low-quality tight-gas reservoirs. In this study, crushed-rock and full-diameter core measurements from two wells drilled with oil-based mud are compared to evaluate which of the two core-analysis methods is more reliable for water-saturation assessment of a major North American tight-gas siltstone play (Montney Formation, western Canada). Measurements from the studied full-diameter core samples have wide ranges of water saturation (10 to 45%) and bulk volume water (BVW) (0.5 to 2.6%). In contrast, measurements from crushed-rock samples have much narrower ranges of water saturation (10 to 20%) and BVW (0.2 to 0.7%). The lower values and limited range of water-content measurements from crushed-rock samples suggest a significant degree of artificial water loss during sample handling in the laboratory. This conclusion is supported by comparing core-measured BVW with deep-resistivity values from openhole well logs. Full-diameter BVW measurements correlate well with log resistivity, indicating they are generally representative of in-situ reservoir conditions. Crushed-rock BVW values, on the other hand, show no correlation with log resistivity. The results of this study suggest caution is warranted in the use of crushed-rock samples for water-saturation measurements of siltstones or silty shales. Failure to recognize artificial water loss from crushed-rock siltstone samples could lead to an erroneous interpretation of irreducible water saturation at in-situ reservoir conditions with potentially serious implications for resource evaluation and exploitation.

An experimental study on CO2/water displacement in porous media using high-resolution Magnetic Resonance Imaging

CO2/water displacement process in porous media under sequestration conditions was observed using high-resolution Magnetic Resonance Imaging (MRI) technique. The porous media was a packed bed filled with glass beads. Fast spin echo multi slice sequence (FSEM) was used to measure the distribution of CO2 and water in the porous media. For immiscible displacement experiments, three stages were obtained from the MR signal intensity profile. The CO2 channeling or fingering phenomena was obviously for the difference of permeability during the second stage. The final water residual saturation depended on permeability, and lower permeability always leads to larger final saturation. For miscible displacement, the displacement process was also divided into three stages from MR signal intensity profile. The MR signal intensity decreased gradually for the resolving of CO2 into water in the first stage. A piston-like miscible front moved uniformly from the top to the bottom of the FOV (field of view) during the second stage, and the MR signal intensity decreased sharply. The displacement efficiency in miscible displacement is larger than that in immiscible displacement process. It is clear that water displacement efficiency or average CO2 saturation depends on flow rate. With the CO2 flow rate increasing, the relatively uniform CO2 distribution and the uniform CO2 front occurred. Additionally, final water saturation decreased. With the core analysis methods, the CO2 velocities were obtained, which were applied to evaluate the capillary dispersion rate, viscous dominated fraction flow and gravity flow function. The capillary dispersion rate donated the effects of capillary, which was largest at water saturations of 0.6 and 0.7. At a high flow rate, the viscous force was dominated over the porous media. When at a low flow rate, the gravity force became important and played a positive role in downward displacements.

CT Analysis Method for Particular Lithology Reservoir Rock

Core analysis is one of the most necessary means to recognize the geological characteristics of reservoirs. Recently, the oil and gas exploration of particular lithology such as volcanic, conglomerate, mud and carbonate rocks continued to make new breakthroughs. As a result, core analysis for particular lithology reservoir rock is increasingly significant. However, conventional methods of core analyzing have great limitations on particular lithology due to the complex chemical components and variable physical status. In order to obtain accurate experimental data and understand the seepage law of particular lithology, advanced core analysis methods are developed through the application of computed tomography (CT). Through the application of nondestructive CT testing for inner construction of core, and the establishing of CT evaluation criterion for the heterogeneity of particular lithology, the goals of analyzing the features and growth of holes and fractures in core and heterogeneity of core are archived. The evaluation criterion is composed by qualitative evaluation and quantitative evaluation, and gives the corresponding evaluation method and formula. The evaluation criterion provides the basis for CT analysis of particular lithology. The application of CT analysis for 211 cores of particular lithology shows: 1) Most conglomerates develops gravel-edge fractures, growth of the fractures is proportional to the level of gravel and inverse proportional to the degree of compaction. Holes in conglomerate are mainly corroding holes between gravel. The growth of holes is related to the composition of cement and compaction. With the lower gravel level, the number of holes and fractures decline. 2) Most volcanic rocks develop holes; some of them develop big holes or lots of holes. Several volcanic samples contain micro-fractures. The growth of holes and fractures in different volcanic rock categories are equivalent, but the type of holes and fractures are different. This research has opened new experimental means for cores of particular lithology. By increasing the skills of core analysis, this research has increased people’s knowledge of reservoir of particular lithology, and means a lot to oil and gas exploration and development.

High-burn up 10 × 10 100%MOX ABWR core physics analysis with APOLLO2.8 and TRIPOLI-4.5 codes

Within the frame of several extensive experimental core physics programs led between 1996 and 2008 between CEA and Japan Nuclear Energy Safety Organization (JNES), the FUBILA experiment has been conducted in the French EOLE Facility between 2005 and 2006 to obtain valuable data for the validation of core analysis methods related to full MOX advanced BWR and high-burn up BWR cores. During this experimental campaign, a particular FUBILA 10 × 10 Advanced BWR configuration devoted to the validation of high-burn up 100%MOX BWR bundles was built. It is characterized by an assembly average total Pu enrichment of 10.6 wt.% and in-channel void of 40%, representative of hot full power conditions at core mid-plane and average discharge burnup of 65 GWd/t. This paper details the validation work led on the TRIPOLI-4.5 Continuous Energy Monte Carlo code and APOLLO2.8/CEA2005V4 deterministic code package for the interpretation of this 10 × 10 high-burn up configuration. The APOLLO2.8/CEA2005V4 package relies on the deterministic lattice transport code APOLLO2.8 based on the Method of Characteristics (MOC), and its new CEA2005v4 multigroup library based on the latest JEFF-3.1.1 nuclear data file, processed also for the TRIPOLI-4.5 code. The results obtained on critical mass and radial pin-by-pin power distributions are presented. For critical mass, the calculation-to-experiment C– E on the k eff spreads from 300 pcm for TRIPOLI to 600 pcm for APOLLO2.8 in its Optimized BWR Scheme (OBS) in 26 groups. For pin-by-pin radial power distributions, all codes give acceptable results, with maximum discrepancies on C/ E − 1 of the order of 3–4% for very heterogeneous bundles where P max/ P min reaches 4, 2. These values are within 2 standard deviations of the experimental uncertainty. Those results demonstrate the capability of both codes and schemes to accurately predict Advanced High burnup 100%-MOX BWR key-neutron parameters.

Imaging of multiphase fluid saturation within a porous material via sodium NMR

We present in this paper a method to monitor multiphase fluid core saturation through measurement of the sodium NMR signal. In a rock core saturated with water and oil, sodium will be present only in the water phase, and therefore can be used to separate the two fluids. Two dimensional sodium images were taken to monitor the movement of brine into oil saturated rock cores. The measured fluid exchange agrees well with expected behavior from traditional core analysis methods. Indications of damage to the rock structure can be seen from the patterns of fluid imbibition.

Application of complementary methods for more robust characterization of sandstone cores

This paper is based on detailed mineralogical, structural, petrophysical, and geochemical studies of sandstone core samples, using routine core analysis methods. These include X-ray computer tomography (CT) scanning, magnetic resonance imaging (MRI), particle size analysis, point counting based on petrographic thin sections, environmental scanning microscopy (ESEM), X-ray diffraction (XRD), and X-ray fluorescence (XRF). In this study, we demonstrate the feasibility of combing these complementary methods in the characterization of reservoir properties of sandstone cores. Four types of sandstones (Slick Rock Aeolian, Fife, Locharbriggs, and Berea sandstones) that differ in grain size, porosity, and mineralogy have been characterized. The results of the different methods used were found to be consistent with each other, but the combination of a variety of methods has allowed a fuller characterization of the rock samples than each method used on its own, bringing out subtle variations in petrographic characteristics that add significant value towards a better description of reservoir properties. For example, it becomes apparent that some types of rocks like Berea sandstones thought to be homogeneous are in fact heterogeneous. The recognition that rock heterogeneity at the sub-centimeter scale may have a significant effect on hydrocarbon recovery requires that field-scale reservoir models take account of these small-scale effects in order to lay claim to reasonable accuracy in production forecasts.

Discussion

In the section of the paper titled “The Formation of Self-Similar Structures,” the authors describe the essential aspects of Constructal Theory. However, Professor Adrian Bejan from Duke University has been working for a long time in putting together the ideas and the formalism of this theory—he actually gave it the appropriate name of “Constructal” 1, and has analyzed many examples in nature and engineering within the framework of this theory, extending it to a variety of situations, with his original contributions, most of them nicely described in his book 2. After having reviewed the book written by Professor Bejan 3 and having closely followed his publications during the last decade, I found that the core analysis and synthesis methods of Constructal Theory are totally based on the author’s own research experience during many years, previously published in specialized journals and books, and supported by many observed facts and results, fully documented in the open literature. The Constructal Theory, established by Bejan, explains how certain basic elements, individually and collectively optimized to form an arrangement, are employed to construct more complex natural systems, within the specific constrains imposed by the physics in every case.The paper by Chai and Shoji is full of ideas and expressions of Constructal Theory that were first contributed and published by Professor Bejan, especially the discussion about academic and industrial implications, in the “Concluding Remarks.”

Measurements of viscosity and permeability of two phase miscible fluid flow in rock cores

This paper describes the application of 1H magnetic resonance imaging (MRI) to the measurement of fluid viscosity and rock core plug permeability during two phase miscible displacements in certain rock types. The core plug permeability was determined by monitoring glycerol solutions displacing D 2O. Simple physical principles were used to calculate the core permeability from the measured displacement angle for a set of Lochaline sandstone core plugs. In a further experiment the viscosity of polyacrylamide solution 1500 ppm was determined in the core plug. The permeability and viscosity results compared well to conventional core analysis methods.

WANDOO—A NEW TREND

In June 1991 a flow of 4 560 barrels of 19° API oil per day, from a depth of 600 m, heralded the discovery of a new hydrocarbon trend along the eastern margin of the Dampier Sub-basin on the North West Shelf of Australia. Wandoo–1 recovered oil and gas from lower Cretaceous sands associated with the M.australis dinoflagellate zone (Barremian), and gas from lower Jurassic Aalenian sands.The main reservoir at Wandoo is the M. australis Sandstone Member of the Muderong Shale. This is interpreted to be a shelfal shoal sand deposited in a minor regression phase during the regional transgression of the Muderong Shale. This reservoir is split into two main lithotypes, a glauconitic subarkose to subarenite, and an overlying greensand. Oil and gas have been recovered from both units, which are considered contiguous for reservoir definition. General reservoir parameters are exceptional. Since the initial discovery a 3D seismic survey has been acquired and appraisal drilling has proven approximately 250 MMSTBOIP.The unusual features of the field necessitated innovative exploration techniques and the need for a strong appraisal program. These techniques included a six streamer, high resolution, three dimensional seismic survey and its associated processing; development of methods to recover and preserve core in extremely unconsolidated sediments; use of non destructive core analysis methods such as nuclear magnetic resonance; and petrophysical analysis that incorporates the resistivity suppression problems of glauconite. Without core a very pessimistic view would have been taken of the M. australis Sandstone reservoir.The Wandoo discovery is on an exciting new trend previously overlooked due to the shallowness of reservoirs, lack of locally recognised source rocks and the dominance of other oil and gas trends in the Dampier Sub-basin and Barrow Sub-basin to the south.

Evaluation of devonian shale with new core and log analysis methods : Luffel, D L; Guldry, F K; Curtis, J B J Pet TechnolV44, N11, Nov 1992, P1192–1197

Evaluation of devonian shale with new core and log analysis methods : Luffel, D L; Guldry, F K; Curtis, J B J Pet TechnolV44, N11, Nov 1992, P1192–1197

New core analysis methods for measuring reservoir rock properties of Devonian shale : Luffel, D L; Guldry, F K J Pet Technol V44, N11, Nov 1992, P1184–1190

Development of a new method involving crushed core samples to measure porosity and fluid content accurately in the black, organic-rich Devonian shales in the Appalachian basin. In the four wells studied, average core bulk volume of gas and porosity ranged to 4% and 8%, respectively, values substantially higher than previously reported