The influence of perturbed stresses near faults on drilling strategy: A case study in Blacktip field, North Australia
MetadataShow full item record
When in-situ stresses are disturbed around large scale fractures, typically faults, the direction of principal stresses can deviate from the regional trend to a completely new direction. This can have a great impact on engineering design and planning. In a gas field offshore Australia, a number of drilling difficulties and wellbore instability were reported at lower depths of one of three wells, while two wellbores in the field did not encounter similar problems. A detailed geomechanics study performed on the wellbore of interest indicated that it approached one of four major fault planes in the area as it was drilled deeper. This caused large stress anisotropy between the two horizontal stresses at lower depths, leading to a stress regime change from a normal to a strike/slip regime. The large contrast between the minimum and maximum horizontal stresses induced a number of shear failures in the form of breakouts around the wellbore, which we also observed on caliper and image logs. Accordingly, after performing sensitivity analysis on wellbore trajectory, we developed a mechanical earth model (MEM) to examine the planned well trajectories for the development campaign. The results demonstrate that the existence of natural fractures at any scale may have significant influence on in-situ stresses and stresses induced during construction of an opening.
Showing items related by title, author, creator and subject.
Fallahzadeh, S.; Rasouli, Vamegh (2012)Hydraulic fracturing is a stimulation technique which is used, in particular in unconventional reservoirs such as shale gas and tight sandstones, in order to en-hance production of hydrocarbon. Hydraulic fracturing is ...
Determination of safe mud weight windows for drilling deviated wellbores: A case study in the North Perth BasinLe, K.; Rasouli, Vamegh (2012)Drilling non-vertical wells, which is commonly used to enhance production, in particular in unconventional reservoirs with very low permeability, is subjected to rock mechanics related issues namely wellbore instabilities. ...
Practical application of failure criteria in determining safe mud weight windows in drilling operationsGholami, Raoof; Moradzadeh, A.; Rasouli, V.; Hanachi, J. (2014)Wellbore instability is reported frequently as one of the most significant incidents during drilling operations. Analysis of wellbore instability includes estimation of formation mechanical properties and the state of in ...