Historical Review and Rock Mechanics Approach to Improve the Wellbore Stability in Nahr Umr Shale Formation

2004 ◽  
Author(s):  
K. Yamamoto ◽  
T. Waragai ◽  
S. Kikuchi ◽  
A.S. Fada'q ◽  
T. Koyama ◽  
...  
Keyword(s):  
Rock Mechanics ◽  
Historical Review ◽  
Wellbore Stability ◽  
Shale Formation

scholarly journals Investigation on influence of drilling unloading on wellbore stability in clay shale formation

2020 ◽  
Vol 17 (3) ◽  
pp. 781-796 ◽  
Author(s):  
Yi Ding ◽  
Xiang-Jun Liu ◽  
Ping-Ya Luo
Keyword(s):  
Wellbore Stability ◽  
Clay Shale ◽  
Shale Formation

The Research of the Oil Base Drilling Fluid Hard Brittle Shale Sidewall Instability Mechanism

2014 ◽  
Vol 513-517 ◽  
pp. 309-313 ◽  
Author(s):  
Guang Feng Zhen ◽  
Go Lin Jing ◽  
Wei Jie Hu ◽  
Bai Sun Liao
Keyword(s):  
Drilling Fluid ◽  
Continuous Production ◽  
Exchange Capacity ◽  
Wellbore Stability ◽  
Instability Mechanism ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mechanism Research ◽  
Shale Formation ◽  
Temperature Time

With the continuous production of the well development, sidewall instability phenomenon has become increasingly serious, mostly occurs in the shale formation, benefit for oilfield produced great harm. Water-based drilling fluid sidewall instability mechanism has been basically clear, the oil-base drilling fluid influence on sidewall stability is not yet concrete. So this paper mainly for oil-based drilling fluid hard brittle shale sidewall instability mechanism research. This article first from the perspective of chemistry, the hard brittle shale borehole wall instability is studied, the experiment tested respectively by the white oil and water treatment of hard brittle shale of cation exchange capacity (CEC) value, so as to analyze the same and the hydration of clay mineral equivalent after processing samples, through analysis of the temperature, time, media's impact on hard brittle shale wellbore stability. Secondly, from the Angle of mechanics, stress and mechanical properties of mud shale formation is analyzed, and the minimum drilling fluid density model, gives a variety of analysis and calculation formula. In addition, this paper adopted the X ray diffraction (XRD)

When Rock Mechanics Met Drilling: Effective Implementation of Real-Time Wellbore Stability Control

2000 ◽  
Author(s):  
I.D.R. Bradford ◽  
W.A. Aldred ◽  
J.M. Cook ◽  
E.F.M. Elewaut ◽  
J.A. Fuller ◽  
...  
Keyword(s):  
Real Time ◽  
Rock Mechanics ◽  
Stability Control ◽  
Wellbore Stability ◽  
Effective Implementation

scholarly journals The Research on Influence of Unloading on Borehole Stability in Clay-Rich Shale Formation

2017 ◽  
Vol 10 (1) ◽  
pp. 204-219 ◽  
Author(s):  
Yi Ding ◽  
Xiangjun Liu ◽  
Pingya Luo ◽  
Lixi Liang
Keyword(s):  
Stress State ◽  
Influence Factor ◽  
Wellbore Stability ◽  
Clay Shale ◽  
New Model ◽  
Rock Structure ◽  
Well Trajectory ◽  
Shale Formation ◽  
Mud Pressure

Introduction: Unloading phenomenon happens in the beginning of drilling and is able to change stress state around borehole. This change of stress state causes impact on rock structure and strength, thus affecting the evaluation of wellbore stability. Especially for determining initial mud pressure, unloading is a significant influence factor. Clay-rich shale formation is well-known for high risk of borehole collapsing, appropriate mud pressure is necessary to stabilize wellbore. Therefore, the unloading influence needs to be considered when it comes to selection of initial mud pressure. Materials and Methods: In this paper, based on the triaxial test, unloading situation has been simulated to investigate the influence of unloading on rock mechanical property. It is shown that clay-shale strength declines with increasing unloading range. Also, note that in comparison with internal friction angle, cohesion has larger decline caused by unloading. Results: Taking account of the unloading influence, new model has been established to investigate wellbore stability. These results demonstrate that unloading creates variable strength decrease at the wall of borehole due to different in-situ stress and well trajectory. This strength decrease gives rise to increasing collapse pressure. In particular, unloading has relatively larger impact in the formation with strong anisotropy and high in-situ stress. Besides, inappropriate well trajectory will increase unloading impact. Conclusion: Finally, this model has been applied to several cases in clay-shale formation, Northern China. And the new model in each case is well consistent with oilfield experience, indicating its practicability and proving unloading is a non-negligible factor for the assessment of wellbore stability.

scholarly journals INTEGRATED OF GEOMECHANICS WELLBORE STABILITY & SWEET SPOT ZONE ANALYSIS TO UNCONVENTIONAL WELL DRILLING OPTIMIZATION

PETRO ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 21
Author(s):  
Allen Haryanto Lukmana
Keyword(s):  
Organic Carbon ◽  
Total Organic Carbon ◽  
Shear Failure ◽  
Horizontal Stress ◽  
Wellbore Stability ◽  
Brittleness Index ◽  
Sweet Spot ◽  
Collapse Pressure ◽  
Laboratory Test Results ◽  
Shale Formation

<strong><em>Abstract </em></strong>Central Sumatra Basin is one of the largest hydrocarbon producer basins in Indonesia. The largest hydrocarbons accumulation in this basin does not rule out the possibility of hydrocarbons also trapped in shale source rock. The potential for hydrocarbon shale is in the Brown Shale Pematang Group layer. The obstacle to development is the depth of the Brown Shale layer so deep that further case studies are needed. This study aims to analyze the geomechanical wellbore stability modelling for drilling and determination sweet spot zone supported by x-ray diffraction (XRD), brittleness index (BI), total organic carbon (TOC) analysis. The geomechanical wellbore stability modelling based on pore pressure, shear failure gradient/collapse pressure, fracture gradient, normal compaction trend, minimum horizontal stress, maximum horizontal stress and overburden gradient analysis. Brittleness index considers each parameter from XRD data which dominantly contains clay, quartz, and calcium. Based on XRD analysis of shale samples from Limapuluh Koto Area, it showed that the samples included the brittle shale group because of the dominant quartz, while the samples from Kiliran Jao were shale brittle because of dominant carbonate (carbonate-rich). From laboratory test results of 8 rock samples from Brown Shale Formation outcrop in Limapuluh Koto Area, it was obtained total organic carbon (TOC) value is 4-17% (average 8%). The shale thickness estimated &gt; 30 m, the brittleness index shale estimated 0.71, and the gradient of over-pressure on Brown Sahle Pematang Group estimated 0.57 psi/ft &amp; 0.53 psi/ft from log data analysis. So the output of this results the study is expected to get stable borehole, minimum of non-productive time (NPT), the problem when drilling such as caving and sloughing. Based on (Mt, 2013), the prospect criteria results can be concluded that the Brown Shale Formation has good unconventional hydrocarbon shale potential. It can be carried out with further research.

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