Ralph E. Flori

Submicron-Pore Characterization of Shale Gas Plays

Gas storage and flow behavior in the shale gas rocks are complex and hard to identify by conventional core analysis. This study integrates clustering analysis techniques from material science, petrophysics, and petrology to characterize North American shale gas samples from Utica, Haynesville, and Fayetteville shale gas plays. High pressure (up to 60,000 psi) mercury porosimetry analysis (MICP) determined the pore size distributions. A robust, detailed tomography procedure using a dual-beam (Scanning Electron Microscope and Focused Ion Beam, also called SEM-FIB) instrument successfully characterized the submicron-pore structures. SEM images revealed various types of porosities. Pores on a scale of nanometers were found in organic matter; they occupy 40−50% of the kerogen body. Two-hundred two-dimensional SEM images were collected and stacked to reconstruct the original pore structure in a three-dimensional model. The model provided insights into the petrophysical properties of shale gas, including pore size distribution, porosity, tortuosity, and anisotropy. This paper presents the pore model constructed from Fayetteville shale sample. The work used X-ray diffraction (XRD) to semi-quantify shale gas clay and non-clay minerals. The Haynesville and Utica (Indian Castle formation) shale samples have a high illite content. The Utica (Dolgeville formation) shale samples show high calcium carbonate (calcite) content. Moreover, wettability tests were performed on the shale samples, and the effect of various fracturing fluid additives on their wettability was tested. Most additives made the shale gas surfaces hydrophilic-like (water-wet). Introduction Unconventional natural gas resources have grown in importance as a complement to conventional fossil fuels as world energy demand has increased. Shale gas is the second largest unconventional energy resource after heavy oil. Recently, the United States Geological Survey (USGS) estimated that tight sands and gas shale in the United States may hold up to 460 Tcf of gas. There are about 200,000 unconventional gas wells in low-permeability sands, coal-bed methane deposits, and shale gas in the lower 48 states. Shale gas is more environmentally friendly and attractive compared to other energy resources due to its ecological advantages (low levels of carbon dioxide CO2 emission) and safety qualities (insignificant sulfur dioxide contents, H2S%). Many petrophysical properties of the unconventional tight gas formations are significantly different from those of conventional reservoirs. In particular, such formations have nano-scale pores and channels, a unique pore structure, and the unusual wettability, transport, and storage properties. These differences produce the fluid flow mechanisms different from those in conventional gas plays, especially when the size of the pore throats differs from the size of the saturating fluid molecules by only slightly more than one order of magnitude. Despite the practical importance of this topic, very little is known about it. Commercial production from extremely low permeability gas reservoirs requires hydraulic fracturing stimulation at the beginning of well production. Proper selection of a fracturing fluid is key to successful stimulation. Currently, selection of hydraulic fracturing fluids for unconventional gas wells borrows from conventional oil and gas techniques. However, shale gas plays have unique properties. For example, the size of the pore throats in shale may differ from the size of the saturating fluid molecules by only slightly more than one order of magnitude. The physics of the fluid flow in these rocks, with permeabilities in the nanodarcy range, is poorly understood.

Animated instructional media for stress transformations in a Mechanics of Materials course

Two unique instructional modules—the Plane Stress Transformations Module and the Mohrs Circle for Plane Stress Module—developed for the Mechanics of Materials course are presented. Formative assessment data gathered from Mechanics of Materials students pertaining to these courseware modules are presented and discussed. General conclusions and recommendations are presented.

Work in progress - instrumentation on a truss adapted for pre-college outreach

Engineering content is a valuable addition to pre-college instruction in science, technology, engineering, and mathematics (STEM) since it applies scientific concepts, illustrates scientific relevance and technology, and provides measurement opportunities. Also, complex systems and interactions can be shown. This work describes outreach resources using a seven-member instrumented truss apparatus. This aluminum bench-top model is scaled to support up to fifty pounds. Electrical resistance gauges are installed on several members for strain measurement. The resource set includes the truss apparatus, instrumentation, a PowerPoint presentation, and a background document. The pre-college objective is a set of demonstration resources for middle or high school classrooms. Effective outreach design is modeled by tailoring to accommodate curriculum standards, level-appropriate concept terms, and grade continuity. The resources were developed by students in an interdisciplinary college class on sensors and structures. The development activities involved testing the models and measurements and refining the construction. Selected resources were implemented and evaluated in a local middle school classroom. The interdisciplinary content includes structural, force analysis, sensing, and measurement components.

The Interdisciplinary Design Engineering Department: A Systems View, a Design Focus and Customizable Interdisciplinary Tracks

Graduates of traditional engineering programs are called on to fill a myriad of interdisciplinary design careers that are increasingly different than historical engineering jobs. These careers focus on complex problems and the importance of solving them quickly in order to be successful corporately and nationally, and demand the use of teams of interdisciplinary, people-and-process-intuitive professionals with special technical skills in engineering systems and engineering design. The students who will be needed to fill these jobs are different as well. They have grown up with computers, have seen that emerging technologies occur at the interface or outside the boundaries of traditional disciplines and are diverse in many ways beyond gender and ethnicity. National trends show smaller percentages of high school graduates are now choosing careers in engineering. In this paper we report on a fresh and innovative type of engineering department that will offer programs carefully designed to augment traditional departments and programs while providing the underpinning engineering design and systems skills to attract and create the engineers needed today. This new engineering department, called Interdisciplinary Design Engineering , will produce graduates who are experts in the process of designing engineering systems.Copyright

Coupling of Low-Salinity Water Flooding and Steam Flooding for Sandstone Unconventional Oil Reservoirs

Abstract In this study, we combined low-salinity (LS) water and steam as a novel enhanced oil recovery (EOR) method that can provide additional oil recovery up to 63% of original heavy oil in place, which is a very promising percentage. The LS water flooding and steam flooding are two novel combination flooding methods that were combined due to the significant effect of both methods in reducing residual oil saturation (especially heavy oil). The laboratory observations of LS water have been conducted by laboratory and pilot tests, which indicated that LS water could increase recovery to 41% of original oil in place. The thermal aspects provided by steam flooding enhanced heavy oil recovery in many field projects. Although the steam provided additional heavy oil recovery, the density difference between injected steam and in situ heavy oil raised badly behaved displacement issues. The problems could be steam channeling, gravity override, and early breakthrough. In view of that, we developed the low-salinity alternating steam flood (LSASF) to gather the benefits of LS water (altering sandstone wettability), reduce oil viscosity by steam, and prevent the steam problems mentioned earlier. Contact angle measurements showed that flooding the core using LSASF method resulted in more water wetness to the sandstone cores. Many scenarios were conducted experimentally, and the laboratory experiments showed that the optimum setup was reducing the injected LS steam cycles. The shorter the injected cycles are, the more the oil recovery is.

Comparison Between Cold/Hot Smart Water Flooding in Sandstone Reservoirs

The incremental oil recovery has been investigated and approved by many laboratory and field projects using water flooding in tertiary stage. The salinity of the injected water is an important factor observed by many researchers. The more salinity decreases the more oil recovery obtained. The investigations on the hot low salinity water flooding have been conducted by many researchers and they found out that it is useful for increasing oil recovery especially heavy oil due to reducing oil viscosity and make it easy to produce to the surface. The thermal expansion of water plays an important role in the incremental oil recovery mechanism, reducing the density of the injected water relative to the aquifer water. This reduces mixing; minimizing thermal loses to the aquifer. Hot water flooding may also increase the economic life of individual wells by as much as a factor of two. Smart water was also used to alter the reservoir wettability and increase oil recovery by manipulating the divalent cations in the injected water. In this study, we used hot and cold smart water and injected both into the sandstone saturated with crude oil in order to investigate the important role of smart water itself and hot smart water. The systematic results showed that changing some cations in the injected brines was better than to spend more money to heat the smart water. The divalent cations Ca2+ and Mg2+ were the most effective component in the smart water. In this study, we also studied the pH effect of the cold/hot smart water effluent smart water EOR.

Practical Strategies and Engineered Solutions to Minimize the Impact of Lost Circulation Problem

Lost circulation is a complicated problem to be banned or combatted during the drilling operations. Mud losses remedies are extensively used to stop or mitigate losses using remedial methods or to prevent mud losses using proactive measures. Lost circulation presents a lot of big challenges during drilling. To address these problems, a number of methods/techniques have evolved over the years. The Rumaila field in Iraq is one of the largest oilfields in the world. Wells drilled in this field are highly susceptible to lost circulation problems when drilling through the Hartha formation. Lost circulation events range from seepage losses to complete loss of the borehole and are a critical issue in field development. This paper describes a study of the lost circulation events for more than 300 wells drilled in the Rumaila field. Lost circulation events were extracted from daily drilling reports, final drilling reports, and technical reports. Key drilling parameters (e.g. ROP, SPM, RPM, WOB, bit type) and mud properties (e.g. mud weight, yield point, gel strength) at the time of each event were recorded along with the lost circulation remedies attempted, and the outcome of those remedies. These data have been analyzed to determine the best ranges of the key drilling parameters that have the greatest chance of mitigating lost circulation in the Hartha formation. Practical field information from the Rumaila field and range of sources have been reviewed and summarized to develop an integrated methodology and flowchart for handling lost circulation events in this formation. In a related development, this paper will be extended work along with previous comprehensive statistical study and sensitivity analysis models about the Hartha formation to obtain the best field procedures for avoiding or minimizing lost circulation events in the Hartha formation. Proactive approaches have been made prior entering the Hartha formation to prevent or mitigate the occurrence of lost circulation. A unique statistical work, primitive mechanisms, typical drilling fluid properties and recommended operational drilling parameters have been evaluated to use during drilling the Hartha formation. In addition, corrective actions have been determined for each kind of the mud losses to provide effective remedies, minimize non-productive time, and reduce cost. Lost circulation strategy to the Hartha formation has been summarized depending on statistical work and economic analysis evaluation to determine the most successful remedies for each type of the losses. These treatments are classified by relying on the mud losses classifications in order to avoid unwanted consequences due to inappropriate actions. This study provides a typical compilation of information regarding traditional approaches and the latest approaches to lost circulation control. In addition, the work attempts to provide useful guidelines or references for both situations in terms preventive measures, remedial methods, and analytical economic study.

Limiting Key Drilling Parameters to Avoid or Mitigate Mud Losses in the Hartha Formation, Rumaila Field, Iraq

Wells drilled in Rumaila field are highly susceptible to lost circulation problems when drilling through the Hartha formation. This paper presents an extended statistical work and sensitivity analysis models of lost circulation events in more than 100 wells drilled in Rumaila field. Lost circulation data are extracted from daily drilling reports, final reports, and technical reports. The volume loss model is conducted to predict the mud losses in the Hartha formation. Observations that are made from the volume loss model are ECD, MW, and Yp have a significant impact on lost circulation respectively; however, SPM, RPM, and ROP have a minor effect on the mud losses. Equivalent circulation density model is obtained to estimate ECD in the Hartha zone, and from this model can be deduced that MW, ROP, and Q have a significant impact on ECD respectively; nevertheless, RPM and Yp have a minor impact on the ECD. The rate of penetration model is made to estimate ROP in the Hatha zone. It is concluded that WOB, RPM, and SPM have a significant impact on the ROP respectively. Due to the lack of published studies for the Hartha formation, this work can serve as a practical resource for drilling through this formation.