BETTER | IMAGING
When selecting and justifying geological drilling targets, the main tool is a combination of evergreen geological and flow simulation models. On their basis the spatial localization of residual reserves, assessment and optimization of production profiles of planned wells, evaluation of their influence on each other, as well as on already existing wells are carried out. In the case of sidetracking, candidate wells are also selected using models. In cases where surface infrastructure and/or production technology constraints are a limiting factor, an integrated model is used along with a three-dimensional flow simulation model. This allows a more accurate assessment of the technological and economic effect of drilling by taking into account the influence of newly introduced wells and well pads on the filed infrastructure.
As production drilling is connected with geological risks (structural uncertainty, lack of net pay thickness, getting into drained or flushed reservoir zones, etc.) when selecting targets, measures to minimize uncertainty impact are defined: choice of drilling sequence and definition of dependent wells, optimization of pilot borehole locations, selection of alternative completion options, etc.
Planned well trajectories are created for selected geological targets. This process takes into account existing technological constraints, including those related to the possibility of complications predicted by the geomechanical model. Well trajectories and pad locations and distribution of geological targets between pads are adjusted to satisfy the interests of drillers, geologists and reservoir engineers. At the end of the day planned trajectories are both drillable and optimal in terms of both subsurface uncertainty and feature production. Integrated well planning is aimed to reduce the cost and timing of drilling while respecting the “interests” of the field development.
At all stages of modern well construction (pilot well, transport section, horizontal section) LWD and MWD channels provide valuable G&G information, which can be used to refine the existing reservoir model ( first of all geological) in order to steer the drilling direction. PetroTrace specialists have accompanied the drilling of more than 500 horizontal wells and sidetracks. Our experience shows high efficiency of drilling monitoring based on comparison of the model data with LWD and MWD data in real time – this improves wellbore to reservoir contact and hence well productivity.
Upon completion of drilling, we carry out fast track log interpretation and update both geological and flow simulation models of the field to refine predictions for the next wells and, if necessary, adjust their targets.
In parallel with geological support while drilling, technological support (technological monitoring) is also carried out, to prevent emergency situations throughout the entire drilling interval. Modern methods of monitoring imply continuous acquisition of mechanical drilling parameters and their comparison with model parameters calculated on the basis of geomechanical model parameters, data on drillability of rocks and results of previous wells.
The tools used for drilling monitoring enable, among other things, pre-drill modeling (to predict risk of incidents) and retrospective analysis of previously drilled (to take lessons and make adjustments to the drilling program for subsequent wells).