Stress state measured at ~7\u2009km depth in the Tarim Basin, NW China

Dongsheng Sun,Hiroki Sone,Bizhu He,Weiren Lin,Haitao Lv,Zicheng Cao,Junwen Cui

doi:10.1038/s41598-017-04516-9

Abstract

The in-situ stress state in the Tarim Basin, Northwest China, down to 7 km depth is constrained using the anelastic strain recovery (ASR) method and wellbore failure analysis. Results are consistent between the two methods, and indicate that the maximum principal stresses (σ1) are close to vertical and the intermediate and minimum principal stresses (σ2 and σ3) are approximately horizontal. The states of stress at the studied wellbore is in the normal faulting stress regime within the Tarim Basin rather than in the compressional tectonic stress regime as in the periphery of the Tarim Basin, which explains the presence of the normal faults interpreted in 3-D seismic profiles collected from adjacent areas. Our results demonstrate that the ASR method can be used for rocks recovered from depths as deep as 7 km to recover reliable stress state information. The in-situ stress measurement results revealed in this paper will help future development of the petroleum resources and kinematics study in the Tarim Basin.

Highlights

While the compressional thrust structures at the periphery generally become the focus of investigation, a large number of small normal faults associated with the Paleozoic-Cenozoic extensional structures are interpreted from seismic data which have triggered discussion on why such structures exist and what marks the transition in the stress state[4, 5] (Fig. 1b)
The results show that the uncertainty in the pore pressure did not have drastic influences on the principal stress magnitudes estimated from the anelastic strain recovery (ASR) method, and stress states predicted from both the upper and lower bound of the pore pressure stayed within the normal faulting stress regime for all 3 samples
This paper presents results from a rare ultra-deep stress measurements at ~7 km depth which is certainly the deepest measurement made within the Tarim Basin and the entire Qinghai-Tibet Plateau area

Summary

Introduction

The images or other third party material in this article are included in the article s Creative Commons license, unless indicated otherwise in a credit line to the material. The in-situ stress state in the Tarim Basin, Northwest China, down to 7 km depth is constrained using the anelastic strain recovery (ASR) method and wellbore failure analysis. The present-day in-situ stress state of Tarim Basin is expected to be dominated by the Himalayan orogeny, promoting thrust faulting. While the compressional thrust structures at the periphery generally become the focus of investigation, a large number of small normal faults associated with the Paleozoic-Cenozoic extensional structures are interpreted from seismic data which have triggered discussion on why such structures exist and what marks the transition in the stress state[4, 5] (Fig. 1b)

Methods

Results

Conclusion