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This unique experience will be held 12-14 October 2020 at the George R. Brown Convention Center in Houston, Texas, USA. These multi-day, hybrid events showcase top industry executives and game-changing leaders who will present their strategies and perspectives through panel, special, and technical sessions. For the first time, attendees will have open access to both societies' technical programs, a combined exhibit floor and joint networking events taking place in Houston. By co-locating these meetings, attendees will be able to leverage greater knowledge sharing and opportunities to expand business relationships. Due to the Colorado Convention Center becoming unavailable for use in October, SPE had to find a new venue for its Annual Technical Conference and Exhibition (ATCE).
Imaging the geology subsalt and at the transition between extra-salt and subsalt has been a challenge at Mad Dog even with extensive seismic data coverage, including two WATS surveys and multiple NATS surveys. WATS acquisition and TTI velocity model processing generated major improvements in the image at Mad Dog. One of the observations of a previous TTI project is the presence of a strong orthorhombic anisotropic effect in a salt mini basin above the field. This finding led to the decision to reprocess the Mad Dog data with a tilted orthorhombic (TOR) velocity model. The main objective of this project is to build an orthorhombic velocity model with nine parameters compared to five with the TTI processing. The TOR anisotropic parameters are generated with the latest FWI and tomography techniques and take guidance from the stress field from a geomechanical model. The outcome of the project is very encouraging with results including better constructive imaging in crucial areas of the field, an incremental increase in signal-to-ratio everywhere and increased fault resolution. The TOR velocity model will be used to migrate a future ocean bottom nodes survey to address some of the remaining imaging challenges.
Presentation Date: Wednesday, October 17, 2018
Start Time: 8:30:00 AM
Location: 208A (Anaheim Convention Center)
Presentation Type: Oral
Maharramov, Musa (ExxonMobil Upstream Research Company) | Chen, Ganglin (ExxonMobil Upstream Research Company) | Routh, Partha S. (ExxonMobil Upstream Research Company) | Baumstein, Anatoly I. (ExxonMobil Upstream Research Company) | Lee, Sunwoong (ExxonMobil Upstream Research Company) | Lazaratos, Spyros K. (ExxonMobil Upstream Research Company)
We present a multiscale time-lapse full-waveform inversion (4D FWI) technique based on a cascaded time-domain simultaneous inversion of multiple surveys with a model-difference regularization. In our cascaded approach, different model scales are recovered using different objective functions and regularization penalties. We apply our method to a synthetic example, and demonstrate a robust recovery of production-induced velocity changes in the presence of repeatability issues and errors in the amplitude information.
Presentation Date: Wednesday, September 27, 2017
Start Time: 10:10 AM
Presentation Type: ORAL
Berkhout, Augustinus (Delphi Consortium, Delft University of Technology, Delphi Consortium) | Blacquière, Gerrit (Delphi Consortium, Delft University of Technology, Delphi Consortium) | Verschuur, Dirk (Delphi Consortium, Delft University of Technology, Delphi Consortium)
Low frequencies are very important in seismic imaging. They penetrate deeper and they are indispensable in impedance estimation. High frequencies enhance the resolution and provide detailed information. In this paper the following three steps are proposed to realize ultra wideband seismic images: a) broaden the linear bandwidth during acquisition by applying DSAs (dispersed source arrays), b) add the missing ultra-low frequency information (trend) from migration velocities, indispensable for impedance images, and c) add the missing ultra-high frequency information (detail) by data obtained from borehole measurements, particularly for reflectivity images.
Presentation Date: Wednesday, September 27, 2017
Start Time: 3:05 PM
Presentation Type: ORAL
Last year, OSHA promulgated a chemical-specific standard for Respirable Crystalline Silica (RCS) in the forms of quartz, cristobalite, and tridymite. Among other impacts of the standard, it lowered the Permissible Exposure Limit (PEL) significantly and established an Action Level (AL) at one-half the PEL that triggers various aspects of the standard. Medical surveillance is required if workers are exposed to greater than the AL for 30 days or more per year. This chemical-specific standard is different from the others in that it requires the use of objective data by employers to demonstrate compliance in industries or work environments known to carry the risk for exposure to RCS. This document focuses on the general industry standard, 29 CFR 1910.1053.
The standard incorporates a phased compliance approach within five years of the effective date, June 23, 2016. Most aspects of the standard become enforceable within next year in 2018. Medical surveillance is required for workers found to be exposed to RCS levels at or exceeding the PEL on that date; however, employers are allowed to delay surveillance activities for workers exposed to less than the PEL but at or more than the AL until 2020. Operations involving hydraulic fracturing have one more year, in 2021, to implement feasible engineering controls. This is likely due to ongoing partnership activities occurring between that industry and OSHA.
The previous PEL was based on epidemiological and toxicological research available prior to the publication of the 1968 ACGIH Threshold Limit Values (TLV’s) that were incorporated into Subpart Z at the time of promulgation in the early 1970’s. Much more has been learned about the effects of exposure to RCS in the 50 years since. The primary disease associated with exposure is silicosis, or a type of pneumoconiosis that results in chronic progressive obstructive pulmonary disease. Besides the obvious reduction in the quality of life among affected workers, the disease may result in lung cancer. Other diseases, such as those affecting the kidney or an increased susceptibility to tuberculosis are also known to be associated with exposure to RCS. OSHA estimates the exposure limit reduction along with medical surveillance will save 642 workers annually from these occupational diseases.
RICHARDSON, Texas (26 October 2009) -- The Society of Petroleum Engineers (SPE) and the Society of Exploration Geophysicists (SEG) have formalized an agreement for intersociety cooperation to benefit their global membership through joint events, programs and services. "This is an exciting opportunity for both societies to build on an already strong relationship to enhance technical knowledge exchange globally that will benefit our members and serve the upstream oil and gas industry," said Behrooz Fattahi, 2010 SPE president. "We can see many opportunities to work together on events for our members, as well as for university student activities, young professional programs and our energy education outreach for pre-university students that will help prepare the next generation for careers in our industry." "We have a number of areas of overlapping interest, and know that our efforts to work more closely together on the operation of conferences will be appreciated by the petroleum industry by allowing them to reach both geophysicists and engineering professionals in one venue," said Larry Lines, 2009 SEG President. "SEG's strong network of sections and associated societies and its large cadre of student chapters and student members provide an excellent platform for collaboration."
Recent advances point to a road ahead to sources that will be based on much lower pressures and much larger volumes than today’s airguns. Low pressure sources will be broader band and emit less noise at frequencies that are too high to be useful; to rotation sensors that will provide complete recording of all degrees of freedom and will measure the full wavefield—not done by today’s four component nodes; to motorized unmanned surface vessels towing streamers that compared to today’s methods will provide more affordable wide-azimuth and long-offset data; and to practical joint multi-mode imaging data analysis methods replacing today’s uni-mode methods and producing earth models that best explain all wave modes.
A chain is as strong as the weakest link. The seismic value chain includes sources, receivers, their geometry, and the data analysis.
Seismic sources are not very different from the airguns that we used decades ago when streamers were solitary, nasty, brutish, and short (adapted from Hobbes, 1651). They are very inefficient; only a few percent of the energy that they release generate acoustic waves at useful frequencies. We need sources with more low frequency signal and less high frequency noise. Chelminski (2014) proposed a new type of source, an evolution of the airgun with significant mutations; radically reducing the pressure, radically increasing the volume, and new design of the ports and the shuttle that will increase the rise time of the released air, generate a near toroidal bubble with larger initial air-water contact area that will reduce cavitation and couple better to the water to generate lower frequency acoustic waves.
Low-pressure sources have not yet been built. There are plans to modify a conventional airgun with new design features and test it at very low pressure this summer, but the experimental data available to us now is limited to conventional airguns with pressure drops down to 1460 PSI. The available data do not span the full range of pressures and volumes that we anticipate and do not account for new design features. We therefore see the following analysis as a worst case scenario expectation. We selected to compare a 400 cubic inch airgun at 2040 PSI to a 580 cubic inch airgun at 1640 PSI. We selected these pressure-volume pairs having calculated the same mechanical energy released in an adiabatic expansion. The lower-pressure airgun has a lower first break, higher first bubble, and slightly larger bubble period (Figure 1). The lower-pressure airgun releases the energy slower, but eventually reaches the same energy (Figure 2). The most significant difference occurs in the first few milliseconds (Figure 3). Figure 4 shows that we gain 1.5 dB at the analog low-cut frequency. This is with a 30% pressure drop (from 2040 to 1460 PSI) and with no new design. We calculate that with a 75% pressure drop from 2000 to 500 PSI, 500% volume increase (from 500 to 2500 cubic inch) and new design we would gain 6dB in the low frequencies, which at the Rayleigh-scattering coupling of 24 dB/octave translates to ¼ octave. This means that the low-cut frequency will decrease from 3Hz to 2.5Hz—a small but geophysically significant advantage. The increase in ocean noise that is implied by lowering the source analog low-cut from 3Hz to 2.5Hz is insignificant to nil. At 2.5Hz, the output of any airgun is over 24dB down from its peak output that is at the bubble frequency of 5-10 Hz, and it is over 50 dB lower that natural ocean noise below 1 Hz.
We conducted a field test that indicated filtered m-sequences potentially to be just as effective as linear sweeps for controlling land vibrators in non-simultaneous operation. In another test, we evaluated the effectiveness of m-sequences modified by a timedomain filter as pilots driving land vibrators in simultaneous multi-sourcing. Results from the multi-sourcing survey indicated that the time-domain filtered pilots produced deblended seismograms somewhat degraded by an unsatisfactory level of crosstalk interference. The crosstalk originates from large-amplitude arrivals generated by adjacent and nearby vibrators. Numerical simulations showed that, by filtering pure m-sequences in frequency domain instead of in time domain, we can obtain an improved set of quasi–orthogonal pilots for which crosstalk interference is much reduced. The improvement comes from retaining as much as possible the spectral energy that exists in pure m-sequences at frequencies between 5 and 20 Hz.
In Vibroseis-based land surveys, deblending of raw field data acquired with multiple simultaneous vibrators can be done at the crosscorrelation step if the vibrators are driven by a set of quasi-orthogonal pilot signals. In the context of Vibroseis acquisition, a quasi-orthogonal set has the following properties: (1) within a restricted window of time lags, the autocorrelation of any single member in the set closely approximates the delta function; (2) within the same time window, the crosscorrelation between any two different members in the set is very nearly zero. The deblending of seismograms using quasi-orthogonal pilots does not depend on differential time moveouts. Among the pilot signals that have been used in this way are variphase sweeps (Krohn et al., 2010), modified Gold codes (Sallas et al., 2011), and Galois codes (Thomas et al., 2010; 2012). Dean (2014) reviewed a variety of pseudorandom signals and their potential suitability as pilots for simultaneous multi-sourcing. Wong (2014; 2013) has shown how maximal-length sequences (m-sequences), a type of pseudorandom binary signal (PRBS) with values only of -1 and +1, can be modified to create effective quasi-orthogonal Vibroseis pilots. This paper describes the continued experimental and numerical evaluation of filtered m-sequences as pilots for Vibroseis-based simultaneous multi-sourcing.
Ivanov, Julian (Kansas Geological Survey) | Miller, Richard D. (Kansas Geological Survey) | Peterie, Shelby L. (Kansas Geological Survey) | Ballard, Robert F. (US Army Engineer Research and Development Center) | Dunbar, Joseph B. (US Army Engineer Research and Development Center)
The primary objective of this work was to determine compressional and shear velocity distribution within the body of five levees and any relationship to existing core taken from the levee and airborne EM data. Several different types of seismic data were recorded at each of the five levee sites, each of which possessed unique core and/or EM characteristics. Several seismic data-analysis techniques were appraised during our main efforts in 2004, including, P- and S-wave refraction, P- and S-wave refraction tomography, Rayleigh and Love-wave surface-wave analysis using multi-channel analysis of surface waves (MASW), and P- and S-wave cross-levee tomography. While the P-wave methods provided reasonable results, the S-wave methods produced surprising shear-wave velocity (Vs) properties. The reason for the latter effect is not clear; possibly the result of mode conversion, which is likely at sites with Poisson’s ratio greater than 0.438. Furthermore, the Rayleigh-wave MASW method could not sample the levees due to lack of high-frequencies of the fundamental mode and complexities of higher modes and, as a result, there were no reliable Vs estimates for the levees. The most recent technological developments that included the use of the high-resolution linear radon transform (HRLRT) with the MASW method for imaging and Love wave inversion, encouraged us to revisit the analysis of horizontalcomponent data. The combined contribution of both techniques was essential to successfully obtaining Vs estimates that imaged to levees.
The original research project was designed to evaluate the applicability of several seismic techniques to identify, delineate, and estimate the physical characteristics or properties of materials within and beneath levees (Ivanov et al., 2004). Several surface seismic measurements using state-of-the-art equipment were made and analyzed using many well-established methods and some that are in the research stage. These methods included: (P & S) refraction, (P & S) tomography (both 2D turning ray and 3D straight ray through levee), surface wave propagation, and surface wave (Rayleigh wave and Love wave) dispersion curve analysis (MASW).