Abstract
This paper demonstrates the approach to field development that involves geomechanical expert analysis at early stages of planning and development. One of the most important problems raised today by geomechanics experts is late involvement of geomechanical analysis and review in the field lifecycle and its usual occurrence only at the development stage. Such approach might lead to a significant reduction in the spectrum of solutions and opportunities to be used in drilling and subsequent production.
The need for geomechanics was identified early at the stage of the field development plan preparation for the V. Filanovsky Field, the largest in the North Caspian Region. Mindful of the complexity of the geological and drilling conditions of the field area, geomechanical modelling was conducted a 3D geomechanical model was built that made it possible to estimate the borehole stability of the designed wells.
The 3D geomechanical model served as a "foundation" for preparation of a field Basis of Design. It helped to identify the key elements: well design, optimized well paths taking into account the geology and unstable intervals, potential risks, multilateral well sidetracking points, drilling mud type and mud weight, etc.
As a result of an extensive multi-year study, the drilling was performed based on pre-selected and pre-computed parameters along the optimized trajectories planned as per the 3D geomechanical model. To additionally reduce potential risks, the drilling process is accompanied by real-time geomechanical calculations, the purpose of which is not limited to update of safe mud weight window model on the basis of real time data but also includes control of borehole stability, hole cleaning, differential sticking risk, cavings morphology, controlling of equivalent circulation and static density within the safe window, well path update for drillability in case of adjustments. Logging while drilling provides of critical information for permanent update of the geomechanical model and improvement of functions, which allows further optimization of well paths and the most accurate parameters of the "safe mud weigh window".
Geomechanics involvement at the Basis of Design project preparation allowed early exclusion of instability risks and identification of well drilling features that would be impossible to implement at the development drilling stage. The result currently achieved by the above effort is the possibility of drilling absolutely all wells, including extended reach (ERD) wells, without any wellbore instability-related problems. Further changes in the modelling approach will be associated to improvement of related functions to ensure still safer and faster drilling.
A reservoir optimization group has currently been formed to support the field development. The next step in the development of the geomechanical model of the V. Filanovsky field will be coupled geomechanical and reservoir modelling to make it possible to assess the impact of production on the strain-stress state of the formation and, therefore, on the reservoir properties. Updated model will also be used for planning multi-stage hydraulic fracturing in relevant wells.
