GEOPHYSICAL LOG RESPONSES TO VARIATONS IN LITHOLOGY IN BORINGS CLINO AND UNDA, GREAT BAHAMA BANK

Author(s):  
E. ROBERT WARZESKI ◽  
LESLIE A. MELIM ◽  
ROBERT N. GINSBURG
2021 ◽  
Vol 40 (11) ◽  
pp. 823-830
Author(s):  
Nikita Bondarenko ◽  
Sherilyn Williams-Stroud ◽  
Jared Freiburg ◽  
Roman Makhnenko

Carbon sequestration activities are increasing in a global effort to mitigate the effects of greenhouse gas emissions on the climate. Injection of wastewater and oil-field fluids is known to induce seismic activity. This makes it important to understand how that risk relates to CO2 injection. Injection of supercritical CO2 into the Cambrian Mt. Simon sandstone in Illinois Basin induced microseismicity that was observed below the reservoir, primarily in the Precambrian crystalline basement. Geomechanical and flow properties of rock samples from the involved formations were measured in the laboratory and compared with geophysical log data and petrographic analysis. The controlling factors for induced microseismicity in the basement seem to be the hydraulic connection between the reservoir and basement rock and reactivation of pre-existing faults or fractures in the basement. Additionally, the presence of a laterally continuous low-permeability layer between reservoir and basement may have prevented downward migration of pore pressure and reactivation of critically stressed planes of weakness in the basement. Results of the geomechanical characterization of this intermediate layer indicate that it may act as an effective barrier for fluid penetration into the basement and that induced microseismicity is likely to be controlled by the pre-existing system of faults. This is because the intact material is not expected to fail under the reservoir stress conditions.


2018 ◽  
Vol 27 (2) ◽  
pp. 731-746 ◽  
Author(s):  
Michael J. Stephens ◽  
David H. Shimabukuro ◽  
Janice M. Gillespie ◽  
Will Chang

2015 ◽  
Author(s):  
Sophia Weaver ◽  
Xiaohui Xiao ◽  
Rob Vines

Abstract Borehole instability challenges can account for a significant percentage of non-productive time and associated costs in drilling. This is even more so in deepwater subsea wells due to high development costs coupled with the subsurface complexities associated with turbidite reservoirs. Pre-drill borehole stability studies in this field case were performed by evaluating offset well history and geophysical log data and calibrating these against direct well measurements and drilling experiences, with the objective of recommending the appropriate mud weight. However, the validation of the pre-drill borehole stability model derived from sonic data taken in the only offset well in the field was deemed necessary for effective borehole stability monitoring in this case. Additionally, the inability to run wireline in a highly deviated well fuelled the need for acoustic data acquisition using logging-while-drilling (LWD). Sonic data was acquired by LWD (a first in the field) and this aided mud weight optimization to successfully drill the well to TD without any borehole stability problems. This paper describes the application of this solution to managing well delivery uncertainties in a deepwater field and highlights the process, results and lessons from the event to aid future applications.


Sign in / Sign up

Export Citation Format

Share Document