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Characterizing subseismic faults from SK-2 drilling core (2900-4200 m); implication for reservoir transmissibility and regional tectonic evolution

Liang Shujun, Gan Wei and Wang Chengshan
Characterizing subseismic faults from SK-2 drilling core (2900-4200 m); implication for reservoir transmissibility and regional tectonic evolution
Interpretation (Tulsa) (March 2020) 8 (2): SG1-SG11

Abstract

Undiscernible faults on seismic reflection profiles are referred to as subseismic faults. Although most subseismic faults are undetected, they play a significant role in understanding regional tectonic evolution and can influence the flow of oil and gas. The Songliao Basin in northeast China is a typical Meso-Cenozoic continental petroliferous basin characterized by stable sedimentation, rift-depression dual structure, and large-scale oil and gas production. However, the characteristics of subseismic faults and their effect on petroleum resources remain not well understood. We have examined findings from the SK-2 east borehole located in the Songliao Basin, which is the deepest (7018 m deep below the ground surface) continental scientific drilling borehole in East Asia. We identified 46 subseismic faults at 2900-4200 m depths based on the observations of core-scanning images, macro- and microstructures, and well-logging data. Macro- and microstructural analyses indicate that most of the subseismic faults in the borehole indicate normal slip. These observations suggest that these subseismic faults may form in response to regional extension in the Shahezi (K1sh) period. The cross-cutting relationships among several groups of sheared fault planes or elongated veins filled in the fractures likely reflect multistage faulting. The subseismic faults are considered to be related to the nearby larger scale faulting as interpreted on the seismic profile. The spatial correlation between the observed subseismic faults and elevated hydrocarbon concentrations documented by borehole mud gas logging suggests that the subseismic faults might have controlled gas migration in the study area.


ISSN: 2324-8858
EISSN: 2324-8866
Serial Title: Interpretation (Tulsa)
Serial Volume: 8
Serial Issue: 2
Title: Characterizing subseismic faults from SK-2 drilling core (2900-4200 m); implication for reservoir transmissibility and regional tectonic evolution
Affiliation: China University of Geosciences, School of Earth Sciences and Resources, Beijing, China
Pages: SG1-SG11
Published: 20200302
Text Language: English
Publisher: Society of Exploration Geophysicists, Tulsa, OK, United States
References: 48
Accession Number: 2020-041592
Categories: Applied geophysicsEconomic geology, geology of energy sourcesStructural geology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sect., 1 table, sketch maps
N42°30'00" - N49°00'00", E119°00'00" - E129°00'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2020, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by Society of Exploration Geophysicists, Tulsa, OK, United States
Update Code: 202026
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