Pore pressure &‘fracture gradient’ assessment (PPFG)
When drilling any well, it is necessary to have a good understanding of the pore pressure and ‘fracture gradient’ conditions to avoid influxes and lost circulation, choose appropriate mud weights and optimise well design. In deepwater environments, this prediction becomes critical due to the low margin between the pore pressure and the fracture gradient (narrow ‘drilling window’) in young and under-compacted sediments. The relationship between the pore pressure and ‘fracture gradient’ is also critical when drilling depleted formations due to the likelihood of ‘stress coupling’ of the fracture gradient to depletion. We offer a full pore pressure – fracture gradient interpretation and prediction service, including remote real or ‘relevant’ time monitoring during drilling.
Wellbore stability assessment (WBS)
Where geomechanically ‘sensitive’ formations are present, uncontrolled wellbore failure (breakout) may lead to drilling, logging and completion difficulties such as tight hole, stuck pipe, packing off, a requirement for significant reaming and/or backreaming, poor quality log data, additional wiper trips or even lost hole sections. The conditions under which those formations will fail, and the likely severity of failure can be predicted by using a geomechanical model, where estimates of key parameters (pore pressure, in situstresses and mechanical properties) are developed and calibrated against offset well drilling experience to create a predictive tool for planned wells. The resulting geomechanical profile (PPFG and wellbore stability plot) helps inform both the well design and drilling practices with the aim of reducing Non-Productive Time related to hole problems.It is not always necessary to completely prevent wellbore breakout (depending on well objectives), as a limited extent of wellbore failure can generally be tolerated. However, specific drilling, hole cleaning and tripping practices are required to manage the resulting hole conditions. The critical issue is to understand the sensitivity of the formation to changes in wellbore pressure and fully integrate the WBS results into the well design and drilling programme.
Completion stability assessment (‘Sanding’)
Designing a well / field development for the worst-case of sand production has a significant impact on the field development plan, type of completion, well productivity/injectivity and overall costs. A completion stability assessment can help optimise both completion and facility design, reducing unnecessary costs and maximising productivity. Where field re-development is planned (conversion to gas storage, for example), additional analyses may be performed to determine the impact of cyclic loading on rock fatigue to help determine overall project viability. The behaviour of injector wells is a specific case, where thermal and pressure transient effects may cause significant formation failure and solids production.
Real / ‘Relevant’ Time Pore Pressure and Geomechanics monitoring for drilling operations
This service allows implementation of geomechanics-based recommendations, and involves monitoring of conditions during drilling using a web-based information system. Direct streaming into a ‘live’ model is possible, with regular updates provided to the client, both in report format and during attendance at meetings such as the Morning Call.
Post-drilling geomechanics assessments
This is a key part of the ‘Lessons Learned’ process, and should be included in the End of Well report. Existing geomechanical models can be updated for future wells and data deficiencies highlighted and incorporated in forward planning.
Contractor supervision / monitoring&peer reviews / assists
We are independent, with no tools or other services to sell. As such, we can help you gain the maximum value from existing / ongoing geomechanical studies by monitoring your contractors and providing advice on the interpretation and implementation of third-party study results.
We are also able to provide the following services:
- Fault shear assessment;
- Compaction and subsidence analysis;
- Sample selection and supervision of laboratory for rock mechanics testing;
- Interpretation of rock mechanics testing results;
- Specification of 3D geomechanical modelling studies, derivation of input parameters and review of results;
- Derivation of input parameters for fracture stimulation modelling.