Thesis (M. S.)--Texas A&M University, 2008. / "Major Subject: Petroleum Engineering" Title from author supplied metadata (automated record created on Oct. 13, 2008.) Vita. Abstract. Includes bibliographical references.

Thesis (M. S.)--Texas A&M University, 2007. / "Major Subject: Petroleum Engineering" Title from author supplied metadata (automated record created on Oct. 13, 2008.) Vita. Abstract. Includes bibliographical references.

<p> Nuclear magnetic resonance (NMR) has become an increasingly important tool for estimating porosity, permeability, and fluid characteristics in oil and gas reservoirs since its introduction in the 1950s. While NMR has become common practice in <i>conventional</i> reservoirs, its application is relatively new to <i>unconventional</i> reservoirs such as the Eagle Ford Shale. Porosity and permeability estimates prove difficult in these exceptionally tight rocks and are routinely below the detection limit and/or resolution of low frequency (2 MHz or less) NMR. High frequency (400 MHz) NMR has been applied to address these issues; however, previous studies have been limited to crushed rock samples or millimeter-sized core plugs. </p><p> In response, a custom-built NMR probe has been constructed, capable of measuring 0.75-inch diameter, 0.45-inch length core plugs at 400 MHz, to determine if larger core plug sizes yield higher resolution <i>T</i>₂ distributions in the Eagle Ford Shale. The tool is composed of two primary elements, the structural framework and the radio frequency circuit. Each element was designed and constructed iteratively to test various layouts while maintaining functionality. The probe's structural design was initially based on retired, commercial probes then modified to operate within a Bruker Ascend&trade; 400WB NMR spectrometer. Designs were drafted and 3D-printed multiple times to determine proper physical dimensions and clearances. Once designs were deemed satisfactory, structural components were manufactured and assembled to create the structural framework. A radio frequency circuit was then built to measure <i>T</i>₂ distributions at the desired frequency and sample size. Multiple inductor designs and capacitor combinations were tested until a stable circuit, capable of matching impedance and tuning to the proper frequency, was achieved. The probe's stability and data quality were then confirmed by measuring the NMR spectra of deuterated water in a Teflon container. </p><p> The NMR probe was validated by comparing high frequency (400 MHz) data acquired in-house to low frequency (2 MHz) data measured at a commercial laboratory. Twelve core plugs (0.75-inch diameter, 1-inch length) were cut from two Eagle Ford Shale subsurface cores located in Gonzales and La Salle counties, Texas. Low frequency <i>T</i>₂ distributions were measured twice: first after drying core plug samples in a vacuum oven and again after spontaneous imbibition with various brine solutions (deionized water, 8 wt.% KCl, or 17.9 wt.% KCl) for one week. These contrasting saturation states were applied to highlight immovable water in the core plugs. For high frequency data measurements, samples were trimmed to 0.45-inch lengths to fit inside the newly-built NMR probe, leaving two sub-samples for each of the original core plugs. <i> T</i>₂ distributions were first acquired "as-is" (e.g., without drying or imbibition). After as-is data acquisition, samples were dried in a vacuum oven then allowed to spontaneously imbibe the same brine solutions used in the low frequency study. <i>T</i>₂ distributions were measured again after imbibition and compared to the low frequency data acquired by the commercial laboratory. </p><p> Qualitatively, high frequency <i>T</i>₂ distributions resemble low frequency data; however, the absolute <i>T</i>₂ values are routinely higher by one order of magnitude. The difference may be caused by data acquisition, data processing, fluid-rock interactions, magnetic field inhomogeneities, or some combination thereof. In spite of not attaining the higher-resolution <i>T</i>₂ distributions desired, the project still provides a proof-of-concept that <i>T</i>₂ relaxation times can be measured in conventional-sized core plugs using 400 MHz NMR. Although limited in its outcomes, the study delivers promising results and elicits future research into utilizing high frequency NMR spectroscopy as a petrophysical tool for unconventional reservoirs.</p><p>

<p> The recent and rapid growth of horizontal drilling in the Anadarko basin necessitates newer studies to characterize reservoir and source rock quality in the region. Most oil production in the basin comes from the Granite Wash reservoirs, which are composed of stacked tight sandstones and conglomerates that range from Virgillian (305&ndash;299 Ma) to Atokan (311&ndash;309.4 Ma) in age. By utilizing geophysical well logging data available in raster format, the Granite Wash reservoirs and their respective marine flooding surfaces were stratigraphically mapped across the regional fault systems. Additionally, well log trends were calibrated with coincident core data to minimize uncertainty regarding facies variability and lateral continuity of these intervals. In this thesis, inferred lithofacies were grouped into medium submarine fan lobe, distal fan lobe, and offshore facies (the interpreted depositional environments). By creating isopach and net sand maps in Petra, faulting in the Missourian was determined to have occurred syndepositionally at the fifth order scale of stratigraphic hierarchy.</p><p>

The development of the quality of gasoline and diesel fuel has never been static. It is no longer newsworthy to say that the world of energy and chemical technology is changing fast. However, these changes are so fast that changes in related technology have to advance at the same speed. Consequently it has been a challenging time for analytical chemists in different types of laboratories involved in the analysis of automotive fuel, such as in the analysis of oxygenates in gasoline, to keep up with all the developments. Since gasoline testing is moving into the stage which requires more advanced technology, laboratories need to be equipped to utilise a range of different techniques in order to suit the peculiarities of the different nature of the samples. During the last few years, the volume of gasoline testing by different bodies such as the independent petroleum laboratories has increased. In practice, laboratories are under considerable pressure to implement the designated analytical regulatory methods, and to constantly improve analytical quality. To help resolve these issues, laboratories sometimes turn to instrument vendors for advice on methodological advances in this type of work. The author has been involved directly with the challenges of this work and has experienced the practical limitations of current methods. Therefore the author has aimed to evaluate various analytical approaches in the study of the characterisation of fuel blending additives and, in particular, oxygenates. This work starts out with an introduction about the development of automobile fuel technology and the use of anti-knock additives throughout the period from the early days to the present. Thereafter further chapters review the current methods applied for the characterisation of these type of fuel additives in gasoline, in particular high performance fuels as used in the motor racing industry. The main aim of this work is to evaluate the strengths and limitations of these methods. The thesis then includes a detailed discussion of different analytical approaches encompassing initially micro-elemental analysis for the direct determination of oxygen content. Then follows the most popular method, gas chromatography, which continues to be the key instrumental technique for the measurement of the main parameters of gasoline. Thereafter follows a study of the GC-MS technique. The next chapter discusses the combustion technique using a Laminar burner to investigate the effect of oxygenates on the reduction of the sooting tendency in diesel. The final method under discussion is the estimation of oxygenates using Nuclear Magnetic Resonance Spectroscopy. Each of the above methods has been used on similar types of samples in different categories. Thus the results may be compared and interpreted using the relevant tables, and correlated against each other. The final part of this work has therefore concentrated on the conclusion of the comparative advantages of each method and its reliability. The main samples used throughout this research work have been actual commercial conventional gasolines and specialised fuels. These have been evaluated against a set of reference standards.

This thesis analyses legal disputes between village communities and oil companies in Nigeria. We have three principal aims. First, the thesis is an attempt to provide a detailed analysis of the nature of legal disputes between oil companies and village communities in Nigeria, particularly in the light of the rise in oil related litigation. Second, the study of litigation is meant to serve as a window to an understanding of social conflicts between village communities and oil companies. Third, the thesis is aimed at making a contribution to the research and the debate on the role of multinational companies in developing countries and on the day-to-day operations of African legal systems. The thesis is organised as follows. Section two analyses the political context of oil operations. Section three provides an introduction to the legal framework by discussing Nigeria's formal legal institutions and oil related statute law. An analysis of a survey of Nigerian lawyers in section four is aimed at evaluating the constraints and opportunities faced by potential and actual litigants in oil related litigation which can either encourage or discourage litigants from engaging in litigation. Focusing on issues such as oil spills and compensation payments for land acquisition, factual evidence from court cases in section five illustrates the adverse impact of oil exploration and production on village communities with a view to identifying the sources of conflict between oil companies and the local populace. A detailed analysis of litigation in section six reveals the principles of tort law upon which oil related cases are based, the legal defences employed by oil companies and legal innovations in oil related cases. Section seven concludes the thesis.

<p> Reactive transport phenomena, such as CO2 sequestration and Microbial EOR, have been of interest in streamline-based simulations. Tracing streamlines launched from a wellbore is important, especially for time-sensitive transport behaviors. However, discretized gridblocks are usually too large as compared to the wellbore radius. Field-scale simulations with local-grid-refinement (LGR) models often consume huge computational time. An embedded grid-free approach to integrate near-wellbore transport behaviors into streamline simulations is developed, which consists of two stages of development: tracing streamlines in a wellblock (a gridblock containing wells) and coupling streamlines with neighboring grids. The velocity field in a wellblock is produced based on a grid-less virtual boundary element method, where streamlines are numerically traced using the fourth-order Runge-Kutta (RK4) method. The local streamline system is then connected with the global streamline system which is produced by Pollock&rsquo;s algorithm. Finally, the reactive transport equation will be solved along these streamlines. </p><p> The presented algorithm for solving near-wellbore streamlines is verified by both a commercial finite element simulator and Pollock-algorithm-based 3D streamline simulator. A series of computational cases of reactive transport simulation are studied to demonstrate the applicability, accuracy, and efficiency of the proposed method. Velocity field, time-of-flight (TOF), streamline pattern, and concentration distribution produced by different approaches are analyzed. Results show that the presented method can accurately perform near-wellbore streamline simulations in a time-efficient manner. The algorithm can be directly applied to one grid containing multiple wells or off-center wells, as well. Furthermore, assuming streamlines are evenly launched from the gridblock boundary or ignoring transport in the wellblock is not always reasonable, and may lead to a significant error. </p><p> This study provides a simple and grid-free solution, but is capable of capturing the flow field near the wellbore with significant accuracy and computational efficiency. The method is promising for streamline-based reservoir simulation with time-sensitive transport, and other simulations requiring an accurate assessment of interactions between wells in one particular gridblock.</p><p>

<p> The vertical and horizontal mechanical properties of a VTI medium can be obtained from five stiffness coefficients (C₃₃, C₄₄, C₆₆, C₁₃, and C₁₂) using velocities at different angles and density measurements. However, when using well log data for vertical wells, only three out of the five elastic constants can be calculated. The sonic tool cannot measure C₁₃ and C₁₂; thus, different empirical models have been proposed to determine them, making assumptions that do not provide completely accurate results. In this paper, a new empirical model is introduced to obtain the stiffness coefficients. Datasets of dynamic core measurements of shales from different parts of the world are compiled and later, analyzed. The method was based on establishing correlations for the stiffness coefficients, both for each formation and for all formations put together. There were two sets of correlations&mdash;those with C₃₃ as the dependent variable, and those with C₄₄ as the dependent variable. M-ANNIE assumptions were also obtained. Because Stoneley slowness is difficult to measure and can cause errors in the calculations, it was not used. </p><p> Finally, isotropic and VTI minimum horizontal stresses are calculated and compared using well log data from the Bakken formation. VTI minimum horizontal stress calculations used the M-ANNIE model and the correlations determined for the Bakken formation core data. Generally, the new model provides results similar to M-ANNIE predictions, and better results than the isotropic and ANNIE models. Although the proposed method produces results similar to those of the M-ANNIE model, which is widely used as a reference model throughout the industry, the proposed method is different in that it can be used under a different set of circumstances when some inputs are available, and others are not. This method reduces the underestimation of minimum horizontal stress made by the isotropic and ANNIE models as well.</p><p>

<p> Integrating Techlog, Petrel, Eclipse, and COMSOL is a game changer and led to a better understanding of a very complex undercompacted and overpressurized sand in Block 276. Different reservoir simulation sensitivity runs on P1-sand indicated that putting a new well in block (2,34) under pure depletion will yield the highest incremental oil recovery of about 38%. The sensitivity runs included dumpfloods, waterfloods, and artificial lift. COMSOL has also shown that formation overlying the salt dome is hotter than other portions of the reservoir and that planning a new well on the western flank of the accumulation was the right decision. COMSOL has also shown that overpressurization is driven by undercompaction but that heat conduction from the dome and underlying diapirs affected pore pressure by 3 to 15%.</p><p>

<p> The shale boom has introduced new technology into the oil and gas industry. It has created a new source of energy and has helped create a surplus in volume. With the recent decrease in oil prices, engineers must be creative and again use technology to make wells more productive. This study is done to observe the role of fracture conductivity in a hydraulically fractured well using a commercially available software. This will allow for engineers to improve fracking techniques. From this, it helps to consider the reliability of simulation software. </p><p> A typical well in the Eagle Ford Shale formation was selected to model. Completion data was gathered for a horizontal well that had seventeen fracture stages. In the simulation models, the fracture fluid volume was held constant to honor the original well production data. The fracture conductivity was studied using two different methods. The first involved observing one single fracture using different combinations of fracture conductivity throughout the fracture length. The second method incorporated the entire well and observed interactions between fractures with different altered fracture conductivities. Only one fracture was used per stage based off an existing fracture model. Production data with respect to time was analyzed and compared to real time field data. </p><p> After production results were analyzed, it can be seen that the models give a reliable representation of a horizontal well in the Eagle Ford Shale. When viewing the results of the single fracture stage, the cumulative productions are very similar, and when comparing the entire well with seventeen stages, the cumulative production begins to change slightly from model to model. Still, the difference in models does not merit an endorsement of a new completion technique for fracture conductivity. The results indicate that infinite acting flow takes over because of the low permeability reservoir. </p><p>