Automated Microseismic Processing and Integrated Interpretation of Induced Seismicity during a Multistage Hydraulic-Fracturing Stimulation, Alberta, Canada

2020 ◽  
Vol 110 (5) ◽  
pp. 2018-2030 ◽  
Author(s):  
Germán Rodríguez-Pradilla ◽  
David W. Eaton

ABSTRACT The development of organic-rich, low-permeability formations for hydrocarbon production requires the use of unconventional techniques such as multiwell pad drilling of horizontal wells and massive multistage hydraulic-fracturing stimulations. However, proliferation of these unconventional development methods has been linked to localized cases of fault reactivation during or shortly after hydraulic fracturing. In the Duvernay formation, located in Alberta, Canada, induced seismicity from hydraulic fracturing has occurred on nearly vertical strike-slip faults that are difficult to detect with conventional seismic exploration methods. In such cases, faults may only be discernible from seismic events with precise and accurate locations, which generally requires dense seismic monitoring arrays deployed near the stimulated wells. In this study, we introduce a new, semiautomated workflow for processing passive seismic data from a dense array and then integrate it with a 3D seismic dataset to characterize seismicity clusters related to hydraulic fracturing and pre-existing faults. The reactivated faults inferred from the distribution of the microseismic events directly overlie a system of incised, middle Devonian channels below the Duvernay formation observed in time slices extracted from the 3D seismic data. The channel system exhibits a set of lateral offsets, interpreted as ancient strike-slip fault displacements, the detection of which is further enhanced by use of a similarity attribute calculated from the 3D seismic data. Taken together, integrated interpretation of induced seismicity and 3D seismic data support a model of a regional left-lateral strike-slip fault system that was active during the middle Devonian and reactivated in a reverse sense (right-lateral strike slip) during hydraulic-fracturing operations.

Geophysics ◽  
2020 ◽  
Vol 85 (6) ◽  
pp. KS185-KS196 ◽  
Author(s):  
Naimeh Riazi ◽  
David W. Eaton ◽  
Alemayehu Aklilu ◽  
Andrew Poulin

Characterization of induced seismicity and associated microseismicity is an important challenge for enhanced oil recovery and development of tight hydrocarbon reservoirs. In particular, accurately correlating hypocenters of induced events to stratigraphic layers plays an important role in understanding the mechanisms of fault activation. Existing methods for estimating focal depth, however, are prone to a high degree of uncertainty. A comprehensive analysis of inferred focal depths is applied to induced events that occurred during completions of horizontal wells targeting the Montney Formation in British Columbia, Canada. Our workflow includes a probabilistic, nonlinear global-search algorithm (NonLinLoc), a hierarchical clustering algorithm for relative relocation (GrowClust), and depth refinement using the recently developed focal-time method. The focal-time method leverages stratigraphic correlations between P-P and P-S reflections to eliminate the need for an explicit velocity model developed specifically for hypocenter depth estimation. We find that this approach is robust in the presence of noisy picks and location errors from epicenters obtained using a global-search algorithm, but it is limited to areas where multicomponent 3D seismic data are available. We have developed a novel method to determine statics corrections to ensure that the passive seismic observations and 3D seismic data share a common datum in areas of moderate to high topography. Our results highlight the importance of transverse faults, which appear to provide permeable pathways for activation of other faults at distances of up to 2 km from hydraulic fracturing operations.


2010 ◽  
Vol 61 (6) ◽  
pp. 483-493 ◽  
Author(s):  
Márton Palotai ◽  
László Csontos

Strike-slip reactivation of a Paleogene to Miocene fold and thrust belt along the central part of the Mid-Hungarian Shear ZoneRecently shot 3D seismic data allowed for a detailed interpretation, aimed at the tectonic evolution of the central part of the Mid-Hungarian Shear Zone (MHZ). The MHZ acted as a NW vergent fold and thrust belt in the Late Oligocene. The intensity of shortening increased westwards, causing clockwise rotation of the western regions, relatively to the mildly deformed eastern areas. Blind thrusting and related folding in the MHZ continued in the Early Miocene. Thrusting and gentle folding in the MHZ partly continued in the earliest Pannonian, and was followed by sinistral movements in the whole MHZ, with maximal displacement along the Tóalmás zone. Late Pannonian inversion activated thrusts and generated transpressional movements along the Tóalmás zone.


2014 ◽  
Author(s):  
Antonio Pico* ◽  
Jesús Aboud ◽  
Felipe Parraga ◽  
Jose Antonio Martinez ◽  
Gonzalo Lopez

2020 ◽  
Author(s):  
Debo Ma

<p>Characteristics and evolution process of strike-slip fault is a key issue restricting further exploration in Halahatang area, North Tarim Basin, NW China. This paper uses the new-acquired 3D seismic data and applies fault structural analysis method to study the characteristics of Halahatang area, and discusses evolution process of the faults.<br>The data used in this paper include 1960 km<sup>2</sup> 3D seismic data in prestack time migration in Halahatang area, and 4 wells logging data used to calibrate seismic horizon. The bin size of 3D seismic is 25 m×25 m with sampling rate of 4ms, and data length of 7000 ms. Firstly, the Eigen-structure coherency and SO semblance are used to identify the distribution of the strike-slip fault. Secondly, the segmentation of Ordovician strike-slip fault in the study area is studied and the control effect of segmentation on reservoir development and oil and gas enrichment is discussed.<br>The slip distance of strike-slip fault is very small, the maximum is no more than 2 km. They are typical cratonic strike-slip faults which are developed inside the craton. There are four kinds of structural styles on the profile, which are vertical and steep, positive flower structure, negative flower structure and semi-flower structure. Five structural styles of linear extension, X type, braided structure, horsetail structure, and en-echelon structure are developed on the plane. There are obvious segmentation along the fault trend.<br>According to the strata subjected to strike-slip deformation and the structural styles in different strata, it is determined that the strike-slip faults have three stages of activity in Halahatang area. <br>In the Late Ordovician, NNE, NNW, NE, and NEE strike-slip faults are mainly developed in the study area. The faults on the seismic profile are steep and upright, with small displacements. Faults generally only break into the Ordovician, and later activities will cause faults to go up to the Silurian and even the upper Palaeozoic, which have different tectonic styles with that of the Ordovician faults. The NNE and NNW strike-slip faults form an “X”-type conjugate strike-slip fault, reflecting the conjugate strike-slip fault is generated by near north-south compression.<br>In the Late Permian, 4 NNW transtensional strike-slip faults are generated by the activation of some Ordovician strike-slip faults. In the Late Cretaceous-Palaeocene, the study area mainly develop several groups of NNE, near SN transtensional strike-slip faults. These transtensional strike-slip faults appear as graben and horst or stepped faults on the section. These transtensional strike-slip faults are R-shear faults in the Mesozoic and Cenozoic strata formed by the Ordovician NNE faults slip dextrally under the tectonic stress.</p>


Author(s):  
V. A. Zhemchugova ◽  
M. O. Berbenev

Most of hydrocarbon resources of Russko-Chaselskiy ridge is associated with reservoirs of Pokur Formation. It is composed generally of alluvial sandstones and shales. Due to genesis Pokur reservoirs have complex structure and localized spread within ancient alluvial plains. Performed integrated interpretation of well and 3D seismic data allowed to estimate new perspective fields and to geometrize oil and gas pulls.


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