Overpressure Generation and Evolution in a Compressional Tectonic Setting, the Margin of Junggar Basin, Northwestern China

Abstract

Overpressure is widespread in the southern margin of the Junggar Basin, northwestern China. Pressure measurements in drillstem tests and repeated formation tests and estimates from wire-line logs indicate contrasting overpressure values between permeable sandstones and adjacent low-permeability mudrocks. In addition, excess pressure differs among anticlines with similar depth, lithologies, and geologic age, indicating significant lateral changes of overpressure. Major factors controlling overpressure generation and distribution include rapid sediment deposition, pressure compartmentalization by thick mudrocks, tectonic stress, faulting, and folding. Clay transformation and hydrocarbon generation are believed to be insignificant in overpressure generation in the southern Junggar Basin. Numerical modeling of pressure generation and evolution suggests that faulting and stratal tilting associated with folding are the most significant factors in the overpressure generation of a permeable sandstone. The extremely high overpressure (pressure coefficient up to 2.43) may have been caused by hydraulic adjustment within permeable sandstones associated with structural deformation caused by post-Miocene intense tectonic activities.

Department(s)

Geosciences and Geological and Petroleum Engineering

Keywords and Phrases

Compressional Tectonic Setting; Mudrocks; Overpressure Generation; Tectonic Stress; Lithology; Mathematical Models; Mechanical Permeability; Pressure Distribution; Pressure Measurement; Sandstone; Structural Geology; Petroleum Geology; Hydrocarbon Generation; Mudstone; Numerical Model; Overpressure; Tectonic Setting; Asia; China; Eurasia; Far East; Junggar Basin; Xinjiang Uygur

Geographic Coverage

Northwestern China

International Standard Serial Number (ISSN)

0149-1423

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2007 American Association of Petroleum Geologists, All rights reserved.

Publication Date

01 Aug 2007

Link to Full Text

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