Petrophysical evaluation methods for shale-gas plays include mineral-based workflows that use traditional nuclear, electrical, and acoustic measurements in combination with advanced geochemical logs. This approach seems to offer the most comprehensive petrophysical analysis for unconventional reservoirs as it seeks an integrated characterization of mineralogy, organic content, porous volume, and fluid distribution. However, this method requires a significant input data set and key model parameters that may not be well known e.g. mineral elemental weight fraction end points. We anticipate variability in geochemical modeling results may arise between operators and service companies, using different model(s) and parameters, or where cross-validation with core data is not possible. The role of geochemical modeling must also be understood in the context of field-wide application, as these data are only infrequently acquired.We discuss results from three interpretation techniques applied in a Haynesville well (Texas) that were calibrated to core analyses from crushed-rock (GRI) methods. First, a multi-mineral approach that includes the standard logging suite and geochemical logs shows that independent petrophysical assessments from two vendors and those from in-house analysis are not in agreement. Second, a petrophysical model that uses resistivity and a combination of two porosity logs is proposed when only these log measurements are available. This model is readily extended to many wells with a common logging suite and may be applied in horizontal boreholes. Third, given sufficient core data across multiple wells, we apply a cluster analysis technique that provides robust results suitable for large regional studies. We compare results from each method to available core measurements and provide recommendations for further applications.In this paper, we also study the role of laboratory NMR measurements to support reservoir characterization of shale gas. Laboratory NMR measurements on preserved core samples are performed in the as-received state. Core NMR porosity and water saturation values are significantly different from those of the crushed-core analysis. This observation suggests that additional laboratory NMR measurements may be required for log calibration.The work described here provides an independent and critical analysis of multiple formation evaluation techniques applied to a Haynesville shale well with core and extensive log measurements. Results highlight the difficulty in developing a mineralbased model using geochemical logs that is consistent with both core and vendor deliverables. Interpretation of NMR data remains an elusive opportunity requiring mostly unknown formation-specific evaluation parameters.
Abstract. The construction of a high-pressure (up to 20 atm) transversely excited CO2 laser using transverse X-ray preionization is described. High pressure operation was found to be greatly improved in comparison to UV-preionized systems. Homogeneous discharges have been achieved in the pressure range 5-20 atm, yielding a specific laser output in the order of 35 J/1. PACS: 42.55E, 42.60B Generation and amplification of short optical pulses in the picosecond range as well as continuous tunability over a complete vibrational band demands an overlap of rotational lines of a molecular laser. In the case of an atmospheric CO2 laser, the bandwidth of a rotational line is only about 4 GHz, and there is no overlap. In that case it is not possible to generate or amplify subnanosecond pulses or to obtain continuous tunability.The gain bandwidth of the CO2 laser can be increased by increasing the pressure of the gain medium. The resulting pressure broadening is about 5 GHz/atm. Although from about 5 atm on, adjacent rotational lines start to overlap, it takes about 15 atm to obtain a continuous modulation-free gain spectrum. An additional advantage of these high operating pressures is that the saturation energy also increases, which offers the opportunity to extract extremely high output powers.Operation of high-pressure COz lasers in the selfsustained discharge regime demands a proper preionization technique to obtain a uniform glow discharge. The best known preionization techniques are UV preionization or electron-beam preionization. Both methods, however, have their own shortcomings. Those of UV preionization are mainly caused by the high absorption rate of UV radiation in (laser) gases. In a typical CO z laser, the effective range for UV preionization is limited to about 0.1 m atm [I]. Using a 300 keV e-beam increases this range only by a factor of two. Furthermore, UV preionization is hampered by an increased dissociation of the CO2 molecules and, when dealing with a spark-source, by gas contamination. This decreases lifetime of sealed-off systems significantly. The main limitation of high pressure e-beam preionized or sustained systems is the window. Because the window has to be transparent for electrons of moderate energy (100-300 keV), thin metal foils are used. On the other hand, these foils have to be sufficiently strong (read thick) to separate the low pressure side (i.e., electron gun room) from the high pressure side (laser chamber).This problem can be circumvented by X-ray preionization. Because of the high penetration depth of X-rays, relatively thick windows can be constructed. Medium-energy X-ray sources have been used successfully in several kinds of X-ray preionized lasers during the last few years [24]. So far, only a few TEMA-CO2 lasers have been described [5,6], with operating pressures up to 10 atm. This paper describes the results obtained with a 20 atm transversely excited COg laser system, using X-ray preionization. The results demonstrate the proper operation at these high pressures.
Summary Standard formation evaluation of an exploration well in the U.K. southern North Sea was supported by magnetic resonance while drilling (MRWD). In this paper we show that even in tight gas sands, MRWD provides information about porosity and producible fluid fraction and allows estimation of formation permeability. This successful introduction of MRWD technology in a known hard-rock environment illustrates a powerful addition to the logging-while-drilling (LWD) tool suite.
fax 01-972-952-9435. AbstractThe Milne Point field in Alaska produces from the Kuparuk, Schrader, and Ugnu formations. The Kuparuk formation contains light oil, while the Schrader and Ugnu contain heavy oil. The ranges of viscosities are 200 to 10,000 cp in the Ugnu, 20 -200 cp in the Schrader, and about 3 cp in the Kuparuk.Over 200 wells have been completed in the Kuparuk and Schrader formations at Milne Point. The Ugnu contains the largest oil in place in the field; however, it has not been developed yet due to the high oil viscosities. To date, only one well has been completed in the Ugnu.BP is engaged in new studies to find a way to make the Ugnu commercial. This paper discusses an attempt to identify lower-viscosity "sweet spots" within the Ugnu using nuclear magnetic resonance (NMR) measurements.In 2004, full suites of logging while drilling (LWD) and wireline data were acquired in two newly drilled wells. The primary goal was to compare viscosity predictions from NMR log measurements to geochemical measurements made on fluids extracted from core plugs. For the first time, on a footby-foot basis, using LWD NMR, lower viscosity sweet-spots were identified in the viscous Schrader formation and in the very heavy oil in the Ugnu formations.
Standard formation evaluation of an exploration well in the UK Southern North Sea was supported by Magnetic Resonance While Drilling (MR-WD). In this paper we show that even in tight gas sands, MR-WD provides information about porosity and producible fluid fraction, and allows estimation of formation permeability. This successful introduction of MR-WD technology in a known hard-rock environment illustrates a powerful addition to the logging-while-drilling tool suite. Introduction Magnetic Resonance (MR) logging has developed into a powerful petrophysical tool for reservoir characterization. The application of downhole MR logging tools has become widespread within the oil- and gas industry. Several "answer" products (like total porosity or bound fluid volume) are now considered to be standard and are reliably provided by the service industry. However, design and completion strategy of development wells often limit or complicate data acquisition using wireline or pipe-conveyed logging. Typical examples are highly deviated, multi-lateral wells, which are commonly required for an economic field development. Furthermore, concerns about borehole stability frequently prevent any traditional open-hole wireline data acquisition. Under these conditions, logging while drilling (LWD) might be the only method of obtaining cost-effective open-hole data for formation evaluation. During the last few years, service companies have made significant efforts to add Magnetic Resonance technology to the suite of LWD tools1,2. The development of MR-WD is complicated by the fact that any MR measurement is very sensitive to vibrations and motions of both the transmitting and receiving RF antenna and the fluids in the sensed volume. As a result, the design of MR-WD tools has to cope with and overcome drilling-induced noise. Halliburton Energy Services have recently introduced their design of an MR-WD tool1. This particular tool was first successfully tested in a Gulf of Mexico well in Q4 20013. Encouraged by this success the MRIL-WD™ tool was included in the bottom hole assembly (BHA) for the reservoir section of an exploration well in the UK Southern North Sea. This was the first use ever of this technology in a known hard-rock environment or in a gas well anywhere in the world. The main objective of this trial was to test the feasibility of MR-WD technology in highly consolidated, low-permeability gas-bearing sandstones. Furthermore, we wanted to investigate potential step changes in cost effectiveness and operational efficiency for a forthcoming development well drilling campaign in late 2003. The MRIL-WD™ tool was run in the 8.5" hole section in combination with various other measurement-while-drilling tools to acquire T1 and T2 data in drilling and sliding modes, over cored and non-cored intervals. In order to verify the data, and to enable local calibrations, subsequent formation evaluation also included MR logging, and a full compliment of standard service, on wireline. MR Logging MR logging exploits the effect of Nuclear Magnetic Resonance (NMR). NMR is a consequence of the intrinsic magnetic moment of protons and neutrons. For most atoms, such as 12C and 16O, the individual magnetic moments of protons and neutrons offset each other, and the effective magnetic moment of such nuclei vanishes. This makes these nuclei invisible to NMR. Protons (1H) provide the strongest NMR response and are typically targeted in NMR logging, but the measured signal can also be affected by the response of other NMR-active nuclei, like 23Na found in brine.
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.