Characteristics of Viscoelastic-Surfactant-Induced Wettability Alteration in Porous Media

Wettability alteration is one of the most important mechanisms of surfactant flooding. In this work, the combined Amott/USBM (United States Bureau of Mines) method was applied to study the average wettability alteration of initially neutral cores after viscoelastic-surfactant (VES) filtration. The effects of static aging, dynamic aging, VES concentration, filtration flow rate, and pore radius on the alteration of a core’s average wettability were studied. The wettability-alteration trends measured by Amott and USBM were consistent, demonstrating that the overall hydrophilicity of the core was enhanced after VES filtration. The wettability alterations of the core brought about by dynamic aging were more significant than by static aging. The viscoelastic properties of the VES played an important role in altering the wettability. In addition, the ability of the VES to affect the core’s wettability was significantly enhanced when the VES concentration was increased, which was beneficial in increasing VES adsorption on the pore-wall surface, thus altering the overall wettability of the core. Increasing filtration flow rates can destroy those high-viscosity VES aggregates via the higher shear rate. A higher retention of VES makes the core more hydrophilic. The difference in the wettability of cores with different pore radius after VES filtration was not significant. The alteration of average wettability caused by VES in porous media provides a new vision for studying the EOR mechanism of VES.

Numerical Simulation Based on the Canister Test for Shale Gas Content Calculation

The accurate determination of the gas in place in shale reservoirs is a basic but challenging issue for shale gas evaluation. Conventional canister gas desorption tests on retrieved core samples and subsequent data analyses (via linear or polynomial regression)—originally developed for coalbed methane, where gases are mainly stored in the adsorbed phase—is unadvisable for shale gas, which is stored as an appreciable amount of free gas in shale reservoirs. In the present study, a mathematical model that simultaneously takes into account gas expansion, adsorption/desorption, and the gas flow in shale is proposed to simulate gas release from a core sample retrieved from the Lower Silurian Longmaxi Formation of the Fuling shale gas field, Sichuan Basin. The results indicate that, compared with the value of 2.11 m3/t rock estimated with the traditional United States Bureau of Mines (USBM) method, the total gas in place within the studied Longmaxi Shale estimated with our mathematical model under reservoir pressure conditions is up to 5.88 m3/t rock, which is more consistent with the result from the new volumetric approach based on Ambrose et al. According to our mathematical model, the content of free gas is 4.11 m3/t rock at true “time zero”, which accounts for 69.9% of the total gas. On the other hand, the lost gas portion is determined to be up to 4.88 m3/t rock (~85% of the total gas). These results suggest that the majority of the free shale gas is actually trapped within the pore space of the shale formation.

A Multifaceted Approach to Advance Oil Spill Modeling and Physical Oceanographic Research at the United States Bureau of Ocean Energy Management

The Environmental Studies Program (ESP) at the United States Bureau of Ocean Energy Management (BOEM) is funded by the United States Congress to support BOEM’s mission, which is to use the best available science to responsibly manage the development of the Nation’s offshore energy and mineral resources. Since its inception in 1973, the ESP has funded over $1 billion of multidisciplinary research across four main regions of the United States Outer Continental Shelf: Gulf of Mexico, Atlantic, Alaska, and Pacific. Understanding the dynamics of oil spills and their potential effects on the environment has been one of the primary goals of BOEM’s funding efforts. To this end, BOEM’s ESP continues to support research that improves oil spill modeling by advancing our understanding and the application of meteorological and oceanographic processes to improve oil spill modeling. Following the Deepwater Horizon oil spill in 2010, BOEM has invested approximately $28 million on relevant projects resulting in 73 peer-reviewed journal articles and 42 technical reports. This study describes the findings of these projects, along with the lessons learned and research information needs identified. We also present a path forward for BOEM’s oil spill modeling and physical oceanographic research.

On the Implications of Automation in the Manufacture Industry on United States Residing Blue-Collar Workers

A study done by the United States Bureau of Labor Statistics found that of men ages 25 to 54, 13.2% were without work (Eberstadt). The British Broadcasting Company (BBC) believes this can be attributed to the increased use of robots—specifically in the manufacturing industry. Since 2000, industrial robots have replaced 1.7 million manufacturing jobs worldwide, and of these 1.7 million jobs, 260,000 were lost in the United States (Robots’ 'to replace up to 20 million factory jobs' by 2030) displaying the massive contribution automation has had on America’s unemployment crisis. According to Workism Is Making Americans Miserable, blue-collar jobs produce tangible products such as coal steel rods, and houses (Thompson) allowing manufacturers to easily replace them with more economically efficient robots. When 1,896 experts were asked the following question, “Will networked, automated, artificial intelligence (AI) applications and robotic devices have displaced more jobs than they have created by 2025?” Half responded that they envision a future in which robots and digital agents have displaced significant numbers of blue-collar workers with much-expressing concern that this will lead to vast increases in income inequality and a breakdown of social order. The other half believed technology will have not displaced more jobs than it creates by 2025 and predicted human ingenuity will create new jobs, industries, and ways of living to ensure jobs are created (Smith). This uncertainty for what lies ahead in the future makes it imperative to determine the extent automation in the manufacturing industry has impacted blue-collar workers in present society. While automation has led to the development and creation of many new jobs, most of these jobs are unattainable for the traditional blue-collar worker causing many to be replaced and without work. Manufacturing corporations must address this issue by improving the effectiveness of worker training programs and providing financial support for workers who have been displaced.

Application of SEM Imaging and MLA Mapping Method as a Tool for Wettability Restoration in Reservoir Core Samples for SCAL Experiments

In reservoir engineering, special core analysis experiments (SCAL) are performed in the lab to evaluate the production capabilities of an oil reservoir. A critical component of SCAL experiments is core wettability restoration to its original wettability, i.e., oil wet condition. Typically, aging is performed by saturating the core with oil and aging at reservoir temperature where time is the variable in question dictating whether the resulting restored core is strongly or weakly oil-wet. In the lab, core wettability is often experimentally validated using contact angle measurements or USBM (United States Bureau of Mines) wettability tests, which are often time consuming, expensive and prone to error. In this study we developed a novel method by using Scanning Electron Microscope (SEM) and mineral liberation analysis (MLA) imaging (at low vacuum conditions) to determine the wettability of rocks saturated with reservoir fluids such as oil and brine. For this work a systematic approach was applied with comparing the SEM-MLA method against conventional methods to quantify the degree of uncertainty linked to a) wettability estimation and b) the aging time. We have used a comprehensive suite of core samples such as Berea, Silurian Dolomite and Chalk to represent the bulk of oil reservoirs in the world.

EVALUACIÓN DE LA ECUACIÓN GENERAL DEL USBR PARA EL DISEÑO DE ALIVIADEROS TIPO CREAGER DE DESCARGA LIBRE

En la actualidad el desarrollo de nuevas tecnologías para el diseño de aliviaderos tipo Craeger ha llevado a implementar modelos numéricos y físicos que permiten analizar la diversidad de formulaciones existentes y pues en ese sentido la presente investigación tiene por objetivo evaluar la ecuación general del United States Bureau Reclamation para el diseño de aliviaderos tipo Creager de descarga libre, escogiéndose como escenario de investigación el tramo de descarga del reservorio Tinajones en las inmediaciones del canal Taymi. La metodología de investigación fue del tipo cuantitativa y de diseño experimental, además fue necesario realizar mediciones de las estructuras hidráulicas existentes en la zona de estudio y se elaboró un registro de aforo del caudal en épocas de estiaje y de máximas avenidas. Los resultados que previamente fueron procesados en un modelamiento unidimensional indican que de las dos secciones propuestas para el diseño del aliviadero tipo Creager la que mejor comportamiento hidráulico desarrolla es la de sección rectangular respecto a una sección trapezoidal y también se concluye que las condiciones de diseño hidráulico se simplifican enormemente para la sección de óptimo desempeño.

A Method for Evaluating the Methane Content of the Nanoscale Pores in Deep Coalbeds

Since the sampling depth is large in deep coalbed methane wells, during the lifting process of coalbed cores, the core surface pressure drops nonlinearly with time, which is contradictory to the premise of the conventional United States Bureau of Mines (USBM) method and the Smith-Williams method. In this paper, a desorption–diffusion model was established to quantitatively characterize the actual escape process of methane gas from nanoscale pores in coal cores in both the wellbore and desorption tank by considering the nonlinear relationship between the core surface pressure and time. Based on the optimization method, the measured volume of the desorbed gas in the desorption tank was fitted, and then, the amount of lost gas in the wellbore was inferred. The calculation result of the USBM method was smaller than that of the method used in this paper. In the calculation model of lost gas volume proposed in this paper, the lost gas time was corrected, and the non-uniform decreasing characteristics of the core surface pressure were considered. Therefore, the lost gas obtained by this model was more accurate than that obtained by the conventional method.

Shale adhesion force measurements via atomic force microscopy

Wettability of sedimentary rock surface is an essential parameter that defines oil recovery and production rates of a reservoir. The discovery of wettability alteration in reservoirs, as well as complications that occur in analysis of heterogeneous sample, such as shale, for instance, have prompted scientists to look for the methods of wettability assessment at nanoscale. At the same time, bulk techniques, which are commonly applied, such as USBM (United States Bureau of Mines) or Amott tests, are not sensitive enough in cases with mixed wettability of rocks as they provide average wettability values of a core plug. Atomic Force Microscopy (AFM) has been identified as one of the methods that allow for measurement of adhesion forces between cantilever and sample surface in an exact location at nanoscale. These adhesion forces can be used to estimate wettability locally. Current research, however, shows that the correlation is not trivial. Moreover, adhesion force measurement via AFM has not been used extensively in studies with geological samples yet. In this study, the adhesion force values of the cantilever tip interaction with quartz inclusion on the shale sample surface, have been measured using the AFM technique. The adhesion force measured in this particular case was equal to the capillary force of water meniscus, formed between the sample surface and the cantilever tip. Experiments were conducted with a SiconG cantilever with (tip radius of 5 nm). The adhesion forces between quartz grain and cantilever tip were equal to 56.5 ± 5 nN. Assuming the surface of interaction to be half spherical, the adhesion force per area was 0.36 ± 0.03 nN/nm2. These measurements and results acquired at nano-scale will thus create a path towards much higher accuracy-wettability measurements and consequently better reservoir-scale predictions and improved underground operations.

Pipeline Geohazards Screening: Using Results of Flood Scour Assessments to Provide a Simple Screening Tool for Pipeline Watercourse Crossings for Western Canada

Pipeline watercourse crossing assessments typically require field investigations, river surveys, and detailed scour analyses to predict whether or not a pipeline may be subject to flood scour deeper than their depth of cover (DOC). Flood scour algorithms rely on discharge, median grain size, and some measure of channel cross-sectional area to determine the tractive force of water on the stream bed. These algorithms are applied to non-cohesive sediments typical of fluvial systems. To better define pipeline threats at a screening level, reducing unnecessary field and analytical expenses, and focusing effort on credible hazards, we developed a flood scour screening tool that uses return period discharge (Q) as the only input requirement. In order to develop the tool, we plotted the results of over 400 detailed scour assessments for several grain sizes (1100 data points) completed in Alberta and British Columbia, in 2017, 2018 and 2019. The results clearly show the importance of channel variability and grain size, but also show definable discharge related trends. We compared the results of the National Engineering Handbook (NEH) and the United States Bureau of Reclamation (USBR) methods, both of which use industry accepted algorithms. We developed, and provided herein, relationships that can be used to screen out scour assessments at watercourse crossings where DOC is already known, or to support and expedite field programs where DOC is being obtained. If only Q is known, then a single graph, or single equation is used for a given region using fine sand as the assumed median grain size. If both Q and median grain size are known, then the user can determine a slightly less conservative result from a series of complementary equations. In all cases, we propose using the mean result of the USBR method, originally intended for design, to fully capture the potential variability in the calculated NEH flood scour. While conservative, the tool is easy to use, and we expect it will substantially reduce the assessment effort on smaller, or less erosive streams.