This paper presents an in-depth assessment of the fracture system created during the Mounds Drill Cuttings Injection Project. The project goal was to evaluate the adequacy of multiple injections in creating a "disposal domain". Previous papers have provided overviews of field results without supporting data or model calculations. This paper presents detailed core, log, tracer, and monitoring field data along with stress calculations, and shows that the Mounds disposal domain is more complicated and less-effective than would appear from the overview data. The principal data defining the cuttings-filled fracture system are from cores drilled through the fracture system and imaging logs of fractures in the borehole walls. Supporting data include analyses of cuttings and induced fractures for tracers (radioactive, dye colorants, glass microspheres) injected with the slurry and fracture-diagnostic results from microseismic and tiltmeter arrays. While all field data show an extensive fracture system, core and log data show that only a few fractures have significant cuttings volume and fracture conductivity. The disposal domain created is one where there is a principal, narrow, cuttings-filled, fracture system, along with abundant, minimal-volume, offset, secondary fractures. Stress calculations also show that insufficient cuttings were injected to reorient the stress field and produce a wide range of fracture strikes. Secondary fractures probably formed from limited localized plugging or activation of intersected natural fractures. However, with sufficient additional injection, a wider disposal domain probably would have been created. Introduction The Mounds Drill Cuttings Injection Project was a joint-industry project organized by the Gas Research Institute (now Gas Technology Institute) and conducted in 1998 and 1999 at the Baker-Hughes Mounds Test Site near Mounds, Oklahoma. The overall project objective was to apply various advanced diagnostic technologies and verification techniques to identify the extent and characteristics of the disposal domain which was created during the batch injection of slurrified drill cuttings. An electronic media report compiling the available project data1 and several additional papers2–4 present overviews of the project background and interpreted results. Upon initiating the project, there were alternate concepts regarding the potential character of the disposal domain. The disposal domain is defined as being those hydraulically induced fractures which accumulate the bulk volume of solids from multiple slurry injections. One concept was that the disposal domain would be characterized by a complex network of slurry-filled fractures having a range of differing orientations. In this domain, the slurry would be deposited in a system of interconnected dendritic fractures with bifurcations which are propagated when horizontal stresses equalize due to the deposition of the slurry. A second disposal-domain concept proposed that a limited number of induced fractures occurring in a relatively narrow strike range would accept the slurry from multiple injections. Several papers5–6 have been published which lend support to the concept that the Mounds slurry-injection disposal domain may have occurred in a wide strike range. This appraisal of the results was based on overall diagnostic information from tiltmeters, microseismic data, and cored fractures that seem to support such a concept. A comparison of the results for these three diagnostic techniques1,6,7 is shown in Figure 1 for the Wilcox injection interval and in Figure 2 for the Atoka injection interval. Shown in each Figure are plan-view projections of the individual microseisms, the locations where cored hydraulic fractures were found, and the tiltmeter projections (strike from surface tiltmeters; length from downhole tiltmeters). A cursory glance at such data would suggest that a relatively widespread disposal domain was created.
Automated speech recognition (ASR) plays a significant role in training and simulation systems for air traffic controllers. However, because English is the default language used in air traffic control (ATC), ASR systems often encounter difficulty with speakers' non-native accents, for which there is a paucity of data. This paper examines the effects of accent adaptation on the recognition of non-native English speech in the ATC domain. Accent adaptation has been demonstrated to be an effective way to model under-resourced speech, and can be applied to a variety of models. We use Subspace Gaussian Mixture Models (SGMMs) with the Kaldi Speech Recognition Toolkit to adapt acoustic models from American English to German-accented English, and compare it against other adaptation methods. Our results provide additional evidence that SGMMs can be an efficient and effective way to approach this problem, particularly with smaller amounts of accented training data.
In the Gulf of Mexico, the rapid pressure depletion and reservoir depth of the Lower Tertiary intervals lead to low oil recovery. A high-reliability, through-tubing subsea electrical submersible pump (ESP) system that takes an integrated approach to production optimization will enable producers to cost-effectively extract more hydrocarbons from the increasingly challenging reservoirs in today's subsea assets. The potential increase in production depends on the maximum drawdown pressure limitations of both well casing design and rock strength. ESPs in deepwater fields are also considered to be an enhancer rather than an enabler by extending the production plateau 5 to 8 years after initial well/field startup with natural flow and seabed boosting. Hence, a robust ESP system that can be installed and operated a few years after field startup without a workover for replacing the upper completions. A robust, reliable ESP would unlock additional value to deepwater operators by delaying CAPEX and eliminating ESP failures, such as degradation of components due to high-pressure/high-temperature (HP/HT) cycling, during the first few years of nonoperation. Designing ESPs for deepwater application is a multidisciplinary challenge and needs to be approached from a full system-reliability standpoint rather than improvements to the ESP hardware alone. Implementation of ESPs in deep water requires both upfront planning at a full-system level and high degree of flexibility for installation, deployment, and retrieval. Finally, because the impact of an unplanned ESP failure is significantly detrimental to project economics, efforts to improve robustness of the ESP hardware must be complemented with automation of ESP operation to reduce or eliminate operator-induced failures. Recent industry improvements in machine learning and predictive analytics need to be leveraged to implement condition-based monitoring of ESPs to better anticipate failures and plan for replacements and/or adjustments to extend the life of degraded units. A collaborative project was undertaken to develop the concept of an alternatively deployed through-tubing ESP (TTESP) system targeted for deepwater subsea operations. The goal was to reduce intervention costs, which, together with ESP run life, are the primary factors influencing the economics of subsea ESPs, including conventionally deployed through-tubing ESPs. The project scope encompassed the downhole hardware, from immediately below the subsea tree through the upper completion, as well as deployment and retrieval equipment and methodology. Economic analyses of subsea fields were conducted to identify the factors contributing to intervention costs so that alternatives could be developed. Multiple concepts were evaluated, and the proof-of-concept system was selected based on superior economic return compared with the baseline. During this proof-of-concept phase, significant testing of key technologies was conducted. The studies showed that conventional intervention vessels and methods will not reduce the intervention costs associated with TTESPs. Lighter vessels together with technologies and methods that minimize intervention time and frequency—and, consequently, reservoir damage and deferred production—are the answer. Eliminating the wait for an available offshore rig is also a key factor in improving overall production economics. The proposed alternatively deployed TTESP system and its associated deployment methodology could reduce the intervention time by half and eliminate reservoir damage. This unconventional deployment could be conducted with lighter service vessels, further reducing intervention costs.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.