scholarly journals Application of Acoustic Emission to Estimation of Strata Denudation: A Case Study from the Ordos Basin, China

2019 ◽  
Vol 11 (3) ◽  
pp. 861 ◽  
Author(s):  
Siyu Wei ◽  
Yanjun Shang ◽  
Yanyan Li
Keyword(s):  
Acoustic Emission ◽  
Dominant Role ◽  
Ordos Basin ◽  
Sedimentary Basins ◽  
Horizontal Stress ◽  
In Situ Stress ◽  
Load Test ◽  
Southeastern Margin ◽  
The Ordos Basin

This paper presents a method for reconstructing denudation in sedimentary basins. The principle of this method is to use the Kaiser effect involving the acoustic emission (AE) of rock samples under a uniaxial load test. Based on the proposed method, the denudation thickness since the Late Cretaceous period in the southeastern margin of the Ordos Basin in China was estimated. The results showed that the denudation increased gradually from the northwest (1600 m a.s.l) to the southeast (1800 m a.s.l) of the study area. A comparison of the denudation results with those obtained from other methods illustrated that the AE method was reliable and easy to use. Finally, using computer simulation, we analyzed the influence of strata denudation and ground topography on the current in situ stress. The results suggested that due to the denudation, the horizontal stress played a dominant role in the distribution of the in situ stress of the study area, but the in situ stress could be reduced by the uplifted movement of the ground. The analysis could facilitate future applications of the AE method and improve understanding of the basin stress field.

New constraints on stress and fracture orientations in the Shipwreck Trough, Otway Basin: implications for conventional and unconventional exploration and production

2012 ◽  
Vol 52 (2) ◽  
pp. 697
Author(s):  
David Tassone ◽  
Simon Holford ◽  
Rosalind King ◽  
Guillaume Backé
Keyword(s):  
Stress Tensor ◽  
Test Data ◽  
Sedimentary Basins ◽  
Horizontal Stress ◽  
In Situ Stress ◽  
New Method ◽  
Natural Fracture ◽  
Log Data ◽  
Maximum Horizontal Stress

A detailed understanding of the in-situ stress tensor within energy-rich basins is integral for planning successful drilling completions, evaluating the reactivation potential of sealing faults and developing unconventional plays where fracture stimulation strategies are required to enhance low permeability reservoirs. Newly available leak-off test results interpreted using a new method for analysing leak-off test data constrains the minimal horizontal stress magnitude for the offshore Shipwreck Trough wells to be ∼20 MPa/km, which is similar to the vertical stress magnitude derived from wireline data for depths shallower than ∼2–2.5 km. Breakouts interpreted from image log data reveal a ∼northwest–southeast maximum horizontal stress orientation and formation pressure tests confirm near-hydrostatic conditions for all wells. The new method for analysing leak-off test data has constrained the upper limit of the maximum horizontal stress magnitude to be the greatest, indicating a reverse-to-strike-slip faulting regime, which is consistent with neotectonic faulting evidence. Petrophysical wireline data and image log data to characterise extant natural fracture populations within conventional reservoirs and stratigraphic units that may be exploited as future unconventional reservoirs have also been used. These fracture sets are compared with possible fracture populations recognised in contiguous, high-fidelity 3D seismic datasets using a new method for identifying fracture systems based on attribute mapping techniques. This study represents the first of its kind in the Otway Basin. Combined analysis of the in-situ stress tensor and fracture density and geometries provides a powerful workflow for constraining fracture-related fluid flow pathways in sedimentary basins.

Analysis of Casing Strength after Casing Wear in Ultra-Deep Rock Salt Formation

2012 ◽  
Vol 616-618 ◽  
pp. 538-542 ◽  
Author(s):  
Fu Xiang Zhang ◽  
Wei Feng Ge ◽  
Xiang Tong Yang ◽  
Wei Zhang ◽  
Jian Xin Peng
Keyword(s):  
Rock Salt ◽  
Coupling Effect ◽  
Equivalent Stress ◽  
Horizontal Stress ◽  
In Situ Stress ◽  
Attrition Rate ◽  
Salt Formation ◽  
Salt Creep ◽  
Casing Wear

To alleviate the problems of casing collapse induced by the coupling effect of rock salt creep and casing wear, the effects of salt creep, attrition rate and casing abrasive position on the equivalent stress on casings in non-uniform in-situ stress field is analyzed by finite-difference model with worn casing, cement and salt formation. It indicates that, creep reduces the yield strength of worn casing to a certain extent; Equivalent stress on casings is bigger and more non-uniform when the abrasion is more serious; Wear position obviously changes the distribution of equivalent stress on casing, and when the wear located along the direction of the minimum in-situ stress, equivalent stress on casing could be the largest that leads to the casing being failed more easily. Equivalent stress on casings increases gradually with creep time increasing and will get to balance in one year or so; In addition, new conclusions are obtained which are different from before: the maximum equivalent stress on casings is in the direction of the minimum horizontal stress, only when the attrition rate of the casing is little; otherwise, it is not. This method could help to improve the wear prediction and design of casings.

scholarly journals A Simple and Accurate Interpretation Method of In Situ Stress Measurement Based on Rock Kaiser Effect and Its Application

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Kang Zhao ◽  
Shuijie Gu ◽  
Yajing Yan ◽  
Keping Zhou ◽  
Qiang Li ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Fractal Dimension ◽  
Principal Stress ◽  
In Situ Stress ◽  
Time Range ◽  
Kaiser Effect ◽  
Time Stress ◽  
Stress Curve ◽  
Interpretation Method

Many deep underground excavation practices show that the size and distribution of in situ stress are the main factors resulting in the deformation and instability of the surrounding rock structure. The in situ stress measured by the Kaiser effect of rock is used by engineers because of its economy and convenience. However, due to the lack of quantitative judgment basis in determining the Kaiser point position, there is a large artificial error in the practical application. In response to the problem, this study systematically investigates the characteristics of rock acoustic emission curve on the basis of the fractal theory and establishes an accurate and simple interpretation method for determining the Kaiser point position. The indoor rock acoustic emission test was carried out by drilling a rock sample at a mine site. By using the conventional tangent method, the cumulative ringing count rate-time-stress curve of rock acoustic emission is analyzed to preliminarily determine the time range of Kaiser point appearance. Considering that the fractal dimension of the rock Kaiser point is lower than the adjacent point, the minimum point of the fractal dimension of this time range can be determined from the fractal dimension-time-stress curve. Such determined point is the Kaiser point. The size of the in situ stress is calculated using an analytical method. Based on the value of the in situ stress, the distribution of the in situ stress in the mining area is further analyzed using the geological structure of the mine. The maximum principal stress is 19.38 MPa, with a direction of N (30°-40°) E, and the minimum principal stress is 8.02 MPa with a direction of N (50°-60°) W. The maximum and minimum principal stresses are approximately in the horizontal plane. The intermediate principal stress is 11.73 MPa in vertically downward. These results are basically consistent with the distribution statistical law of the measured in situ stress fields in the world. The results presented in the study could provide a reference for the later mining, stability evaluation, and support of the surrounding rock.

The measurement of the in-situ stress state by acoustic emission method (AEM) in weak rocks

Rock Stress ◽  
2020 ◽  
pp. 389-394
Author(s):  
H. Watanabe ◽  
H. Tano ◽  
Ö. Aydan ◽  
R. Ulusay ◽  
E. Tuncay ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Stress State ◽  
In Situ Stress ◽  
Acoustic Emission Method ◽  
Emission Method ◽  
Weak Rocks
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