Elfen wellbore is utilised to accurately simulate the well-life process from beginning to end across all environments.
Together with advanced constitutive material models, various complex mechanisms can be captured including, breakout modes, creeping shale, internal / external filter-cake.
Elfen wellbore includes all near wellbore applications such as, stress, stability and loss circulation, fines migration and mud-cake modelling, sanding analysis and prediction, sand screens and advanced completions systems design, near wellbore fracture and damage prediction, and well string assessments (via Elfen horizon).
Utilisation of our software can accurately estimate mud-weight windows and well trajectory optimisation with the ability to model near-wellbore and completion scenarios.
Wellbore case study
Successful hydrocarbon recovery has become increasingly challenging with the oil and gas industry exploring reservoirs under unfavourable geological conditions. Several operations rely on wellbore stability usually provided by suitable mud-weight. Estimating the operating mud-weight window demands sufficient knowledge of in-situ stress conditions, well trajectory and formation material properties to eliminate instability issues. Instability issues become significantly important when drilling in challenging environments, such as depleted formations, highly deviated wells or strongly heterogeneous formations.
Analytical calculations can predict the onset of plastic yielding and damage around a wellbore; however, frequently used criteria have two inherent limitations in not being able to capture 1) complex stress distribution around wellbores deviated from the in-situ stress direction and/or in nonhomogeneous formations, and 2) material softening/hardening due to formation damage and redistribution of stress influencing further damage or stability/instability. 3-dimensional numerical modelling combined with advanced constitutive material models can capture stress conditions around wellbores of any orientation as well as non-isotropic characteristics and post-yield strength softening.
Using efficient modelling techniques, it is possible to perform detailed wellbore stability analysis for a range of stress conditions, well trajectories and formation anisotropy. Consideration of the results provides beneficial information for drilling, such as operating mud weight window and predicted cuttings volume. In this study, Elfen wellbore software is used to provide detailed assessment of both wellbore deviation and formation anisotropy including bedding plane effects. A representative volume is calculated for each case that corresponds to both the deteriorated material around the wellbore and also undamaged cavings separated from the wellbore surface.
The combination of such modelling and results assessment techniques available in Elfen wellbore, aims to enhance current wellbore stability assessments and limit the risks associated with drilling in increasingly difficult conditions. (Rockfield, 2020)
Wellbore case study
Multi-scale numerical geomechanical models for reservoir and overburden deformation in the Tyra chalk field (Denmark) were made, and calibrated by laboratory deformation tests and field data. The mechanical interaction between the compacting and deforming formation, cement and casing was 1) modeled as a function of well orientation, cement distribution, and mechanical properties, 2) followed by probabilistic analysis of the model results in well-failure risking models to gain insight in the effects of rock deformation on well failure, both in space and time, and then 3) used as input in fluid-flow models to forecast the impact of well-failure on production.
The risk analysis revealed that, whilst further Tyra compaction will probably lead to more well failure, its impact on production is probably low. Our geomechanical modeling helped to reduce uncertainty in the high-cost multi-year Tyra Future field upgrade planned for the next years to support Tyra production over the next decades (Rockfield, 2018)
Wellbore case study
Whilst the step-out lengths of proposed ERD wells are becoming more and more challenging, wellbore stability assurance technologies - both in the pre-planning and execution phases - are developing at an equal pace.
In this paper we describe several new developments in theoretical understanding and predictive capability of rock failure surrounding wells drilled at high-angle to bedding that are required to solve the problems encountered in these challenging environments.
Rig-site processes for the integration of this new understanding with real-time diagnostic measurement and monitoring provide the means to deliver borehole stability assurance for ERD wells drilled in the most challenging environments. (Rockfield, 2007)
Wellbore case study
There has been significant debate over the exact mechanisms that allow the sand to be produced and whether the process creates a radial zone of high permeability around the wellbore or more linear high permeability channels (wormholes) out from the reservoir. Numerical modelling of the sand production process presents significant numerical challenges mainly because it is a highly-coupled nonlinear process and requires constitutive models that are able to capture the material instability.
For simulations of the CHOPS process, the model shows that a key aspect of the process is the shifting of the overburden stress from parts of the reservoir sand that fail and are produced to those where the sand has not failed. It is this mechanism that allows wormholes to form in the numerical models. The models have also shown conditions which can be induced in the reservoir to enhance formation of wormholes. Automatic adaptive remeshing for TWC simulation (Rockfield, 2007)