- Home
- A-Z Publications
- First Break
- Previous Issues
- Volume 35, Issue 2, 2017
First Break - Volume 35, Issue 2, 2017
Volume 35, Issue 2, 2017
-
-
I can’t hear you, speak up — A case study of passive seismic monitoring of the CO2 injection at Delhi Field, Louisiana
Authors Isabel White and Thomas DavisPassive seismic monitoring has a variety of applications, most widely to monitor hydraulic fracturing in tight sandstone or shale reservoirs. For hydraulic fracturing, microseismic events can help to define the affected zone of the reservoir and the stress state. For enhanced oil recovery (EOR), wastewater, and carbon capture and storage (CCS) injection projects, passive seismic can aid in understanding the impact of injection on the reservoir or the surrounding formations. In any injection programme, containment and caprock integrity are always a concern. Passive seismic data can help to identify potential fracturing within the reservoir area or the overlying formations. The goal of an enhanced oil recovery (EOR) is not to fracture the reservoir and not to lose CO2 out of zone. CO2 seeping into non-reservoir zones wastes resources. Furthermore, there are potential environmental and legal consequences if CO2 is allowed to migrate closer to the surface. Thus, monitoring is a key component of an injection project. Programmes using passive seismic to monitor CO2 injection have experienced mixed results. A primary research field for fluid injection microseismicity is Weyburn field in Canada. Throughout the project, about 100 events were located up to 1600 ft from a downhole array with event magnitudes ranging from -3 to -1. The majority of events occurred at the start of CO2 injection, with lower levels of activity after (White, 2009). CSS projects, with injection into deeper formations, can have a greater level of microseismic activity (Bauer et al., 2015). In a CO2 injection project analysed by Verdon et al (2010), a number of small events were detected close to the monitor well. The majority of events occurred at the start of injection. A number of campaigns did not record microseismicity at all during injection, such as the Pembina oil field in Alberta, Canada (Martinez-Garzon et al., 2013). Additionally, analysis by Soma and Rutledge (2013) found the microseismicity in Aneth oil field was related to salt water disposal not the CO2 injection. The success of different monitoring campaigns is related to a number of factors including geology, geomechanics, and acquisition geometry.
-
-
-
Introduction — Interpretation of diffractions
Authors Evgeny Landa, Tijmen Jan Moser and Michael PelissierEvgeny Landa, Tijmen Jan Moser and Michael Pelissier present six papers introducing the latest thinking on how diffraction imaging has improved seismic interpretation for both conventional and unconventional resources.
-
-
-
Seismic diffractions: How it all began
Authors Henning Hoeber, Michael Pelissier, Tijmen Jan Moser and Kamill Klem-MusatovWe review in historical order the key contributions to the development of the theory of diffractions. The work of Grimaldi, Huygens and Young provides the first part of this story, giving an understanding of diffraction and interference phenomena. Huygens was able to explain the laws of reflection and refraction, but lacked a deeper understanding of interference. This was provided by Young who used it to show how diffraction could arise from the interference of two waves. Fresnel, Helmholtz and Kirchhoff chose a different path and developed a full mathematical expression of Huygens’ principle, incorporating wave phase and interference. Sommerfeld and his students were able to reformulate the Huygens-Helmholtz-Kirchhoff integral as the sum of an incident geometrical-optics wave and a diffraction integral, which is interpretable as the contribution of the diffracted rays from the boundary. From our modern vantage point, this provides a rather pleasing analogy to Young’s early attempts at a theory of diffraction, using just two rays. A full ray-theoretical theory of diffraction, the Geometrical Theory of Diffraction, was given by Keller and extended by Klem-Musatov and Aizenberg to the case of seismic diffraction analysis.
-
-
-
Diffraction imaging of high-resolution 3D P-cable data from the Gulf of Mexico using azimuthal plane-wave destruction
Authors Dmitrii Merzlikin, Timothy A. Meckel, Sergey Fomel and Yanadet SripanichEdge diffractions are responses from such geologic discontinuities as depositional channels, faults, fracture swarms, etc. We apply diffraction imaging to a high-resolution 3D (P-cable) dataset acquired on the inner shelf, Gulf of Mexico. We generate and interpret azimuthal plane-wave destruction diffraction images and focus on two different geological features observed in the diffracted wave-field: (1) faults, and (2) meandering channels with high and low sinuosity. The crucial step in diffraction imaging workflows is the diffraction/reflection separation procedure with the goal of attenuating reflection energy that typically masks weaker diffraction energy. Plane-wave destruction filters successfully serve this purpose. In 3D these filters operate in two directions – along inline or crossline directions. We apply an extended azimuthal plane-wave destruction imaging workflow, which accounts for various orientations of edge diffractions and allows for their orientation determination. We utilize the azimuth information to identify subtle diffractivity zones with orientations similar to the one of corresponding major faults. We show that diffraction images allow for finer discontinuities’ delineation as compared to conventional reflection images.
-
-
-
High resolution diffraction imaging for reliable interpretation of fracture systems
Authors B. de Ribet, G. Yelin, Y. Serfaty, D. Chase, R. Kelvin and Z. KorenSmall-scale subsurface features, such as natural fractures, act as scattering sources for seismic waves propagating through the subsurface. The wavefield generated by those source points is identified as diffraction energy. The amplitude of this type of energy is much smaller than the recorded events reflected from actual interfaces between different geological layers. Moreover, diffraction energy is normally suppressed by conventional processing and standard imaging algorithms, where summations and averaging processes are applied. The common objective in such processing workflows is to focus on the high specular amplitudes in order to enhance the continuity of seismic reflection events for improving the structural mapping of the subsurface. Our goal is to complement the traditional seismic interpretation workflow by integrating information relative to diffraction energy as another seismic attribute to be interpreted. The technique applied in this paper is based on a depth imaging algorithm that maps and bins the recorded surface information into multi-dimensional, local angle domain (LAD) common image gathers. The advantage of this system is its unique ability to decompose the wavefield into reflection and diffraction energy directly at the image locations. This paper provides a brief overview of the technology and illustrates its benefits when applied to the Eagle Ford and Barnett shale reservoirs, where seismic data can be of moderate quality, leading to accurate, high-resolution, and highcertainty seismic interpretation for risk-managed field development.
-
-
-
Enhancing confidence in fracture prediction through advanced seismic data processing and analysis techniques
More LessInformation on the areas of high fracture can play a key role in the successful development of the majority of carbonate and many other reservoir types. Seismic data are one of the sources of such information and with modern acquisition methods optimally designed to obtain the field data of the highest quality, the possibilities now exist, using the most advanced processing technology, to extract maximum information and knowledge related directly to fracture characterization. We present a technology and analysis to detect fracture and other small-scale geo-features using the products of azimuthal angle depth migration. The migration results give specialists optimal data for obtaining azimuthal anisotropy, separated scattered (diffraction) energy fields as well as standard seismic attributes without the need for azimuthal sectoring. The authors also propose to separate the scattered energy component of the seismic field based on the difference in the kinematic properties of the reflected and diffracted waves rather than the dynamic differences. Following this method of effective separation of reflected and diffracted waves it is suggested to further separate and rank the scattered energy components for identification and localization of small-scaled diffractions. Finally, an efficient and intuitive technique of integration and analysis of all results obtained by different independent methods is presented.
-
-
-
Diffraction imaging enhancement using spectral decomposition for faults, fracture zones, and collapse feature detection in a Middle East carbonate field
Authors Gregg Zelewski, William A. Burnett, Enru Liu, Mary Johns, Xianyan Wu, Je Zhang and Gene SkeithDiffraction imaging is demonstrated in this case study to improve horizontal resolution over conventional reflection imaging. Edge enhancement, using spectral decomposition on diffraction imaged data, further enhances the capabilities of detecting faults, fracture zones, and collapse features improving the spatial resolution and edge detection for higher resolution seismic interpretation. Spectral decomposition also provides an effective tool for separating low-frequency reflection data noise from diffraction imaged data, improving the interpretability of the diffraction imaged data. This case study also demonstrates that edge enhancement using spectral decomposition improves the ability of spatially correlating the edges of collapse features, detected with diffraction imaged data, to drilling mud losses in carbonates. Detecting overburden collapse features with diffraction imaging could provide economic benefits, avoiding encounters with high perm zones, preventing mud loss expenses and increased drilling time, from days to weeks, and controlling the well.
-
-
-
Interpretation value of diffractions and sub-specular reflections – applications on the Zhao Dong field
We provide an overview of integrated pre-stack depth migration and diffraction imaging for the Zhao Dong field, Bohai Bay, China. This field is highly compartmentalized by complex faulting and further characterized by channel systems, fractures and volcanic features. The objective of the diffraction imaging is to better define these small-scale features. Tools to facilitate interpretation include displays with pre-stack depth migration and diffraction images overlain in different colour scales, as well as a weighted blending of them into a single volume. An important concept is that of the sub-specular reflection, which is obtained alongside the pure diffraction image by applying ultra-weak specularity tapers. Tuning properties of elementary diffractor images together with sub-specular reflectors provide a decisive uplift of diffraction imaging for the interpreter.
-
-
-
Practical example of data integration in a PRM environment, BC-10, Brazil
Authors Hesham Ebaid, Kanglin Wang, Marcelo Seixas, Gautam Kumar, Graham Brew and Tracy MashiottaDeepwater developments always represent a huge capital investment, and this is especially true when the field in question is instrumented with Permanent Reservoir Monitoring (PRM). These massive financial outlays demand optimum efficiency to maximize the return on investment. This means taking full advantage of the value in the large volumes of time-lapse seismic data collected. In this paper, we examine enhanced workflows and solutions for optimizing the utility of Permanent Reservoir Monitoring data in a deepwater setting. We do this by fully integrating these data into our subsurface models and decision making in a rapid, thorough, and quantitative fashion. Parque das Conchas (BC-10) represents a major milestone in the development and commercialization of Brazil’s deep water. The project consists of several distinct small-to-medium-sized fields in the Campos Basin that allow for phasing. The fields have been developed using subsea wells and manifolds, all of which are connected to a centrally located floating production, storage and offloading (FPSO) vessel, the Espírito Santo (Figure 1). The Espírito Santo FPSO, which has a processing capacity of 100,000 barrels of oil equivalent per day (BOE/d), was built by SBM in Singapore and delivered to Brazil in late 2008 being moored in around 1800 m of water. The double-hulled FPSO’s design required significant power and heat delivery systems to drive the seabed lift equipment and process the heavy crudes. This development is the first of its kind based on full subsea oil and gas separation and subsea pumping. This system uses 1500-horsepower underwater pumps – each equivalent to a Formula One engine – to drive oil and a small quantity of gas to the surface.
-
-
-
Full-field 4D image modelling to determine a reservoir monitoring strategy
Authors David Hill, Sonika Sonika, Dominic Lowden, Mehdi Paydayesh, Thomas Barling and Mike BranstonThe history of closed-loop seismic reservoir monitoring (CL-SRM) dates back to the late 1990s and early 2000s. Gosselin et al. (2003) noted that, at the time, the seismic forward-modelling step within the proposed workflow was too CPU time consuming. Hence, they confined themselves to ‘closing the loop’ by reconciling the differences between elastic parameter changes predicted from reservoir simulations with measured elastic parameter changes from an acoustic impedance inversion of 4D time-lapse seismic data. In subsequent years, variations of the history matching using time-lapse seismic (HUTS) CL-SRM workflow were developed and generically assigned the descriptors ‘Sim-to-Seis’ and ‘Seis-to-Sim’ workflows, illustrated in Figure 1. Within these workflows, various forward-modelling techniques evolved in line with the availability of computing resources. Three groups of forward-modelling techniques currently in common use are: 1) direct analytical transformation of reservoir properties to seismic acoustic attributes and variations of well-log-based fluid-substitution and petrophysical modelling, 2) 1D convolution modelling, and 3) 2D/3D point-spread function convolutional modelling (Lecomte et al., 2004). The first two modelling techniques neglect effects owing to 3D wave propagation, acquisition geometry, overburden illumination, near-surface effects, and noise. The third incorporates effects owing to acquisition geometry and overburden illumination by means of ray tracing, but still neglects effects owing to 3D wave propagation, the near surface, and noise. In many cases, the study area for such a Sim-to-Seis workflow has a small areal extent and is often confined to the reservoir interval. Moreover, the assumptions inherent in a Sim-to-Seis workflow deliver a forward model that is not necessarily a realistic representation of the measured 4D seismic response and, therefore, renders it difficult or impossible to reconcile the differences and close the loop.
-
Volumes & issues
-
Volume 42 (2024)
-
Volume 41 (2023)
-
Volume 40 (2022)
-
Volume 39 (2021)
-
Volume 38 (2020)
-
Volume 37 (2019)
-
Volume 36 (2018)
-
Volume 35 (2017)
-
Volume 34 (2016)
-
Volume 33 (2015)
-
Volume 32 (2014)
-
Volume 31 (2013)
-
Volume 30 (2012)
-
Volume 29 (2011)
-
Volume 28 (2010)
-
Volume 27 (2009)
-
Volume 26 (2008)
-
Volume 25 (2007)
-
Volume 24 (2006)
-
Volume 23 (2005)
-
Volume 22 (2004)
-
Volume 21 (2003)
-
Volume 20 (2002)
-
Volume 19 (2001)
-
Volume 18 (2000)
-
Volume 17 (1999)
-
Volume 16 (1998)
-
Volume 15 (1997)
-
Volume 14 (1996)
-
Volume 13 (1995)
-
Volume 12 (1994)
-
Volume 11 (1993)
-
Volume 10 (1992)
-
Volume 9 (1991)
-
Volume 8 (1990)
-
Volume 7 (1989)
-
Volume 6 (1988)
-
Volume 5 (1987)
-
Volume 4 (1986)
-
Volume 3 (1985)
-
Volume 2 (1984)
-
Volume 1 (1983)