Lots of cleats, fractures and other weak structures have developed in coal reservoirs, and as a result, there are relatively big difference between its mechanical properties and coal matrix. During the drilling process, the cleats and fractures near the sidewall are more prone to surfer damage than coal matrix under the ground stress, crack stress, fluid pressure and borehole fluid additional stress, and thus destabilizing phenomena such as borehole collapse and circulation loss would take place. This paper used elasticity and fracture mechanics theories, and took the time effect of sidewall rock drilling fluid seepage into consideration to deduct stress intensity factorIandIIat the cleat tip under the action of the fluid-solid coupling, to establish criterion for the failure condition of coal matrix and cleat fractures, and to establish the wellbore stability calculation model for the cleat-featured coal body. Applying the model can calculate the safe drilling fluid density during the drilling process in cleat-featured coal seam, get the influence law of the factors which affect the wellbore stability such as the length of cleats, horizontal inclination of cleats and opening time of borehole, etc, and it also can analyze the time-delay effect of wellbore destabilization during the drilling process in cleat-featured coal seam. The study achievement was the supplement and perfection of the existed estimation model for the wellbore stability of coal seam gas well.

Intelligent digital oilfield (iDOF) operations include the transfer, monitoring, visualization, analysis, and interpretation of real-time data. Enabling this process requires a significant investment to upgrade surface, subsurface, and well instrumentation and also the installation of a sophisticated infrastructure for data transmission and visualization. Once upgraded, the system is then capable of transferring massive quantities of data, converting it into real information at the right time.The transformation of raw data into information is achieved through intelligent, automated work processes, which are referred to here as "smart flows." Smart flows assist engineers in their daily well surveillance activities, helping make them more productive and improve decision making. A major oil and gas operator in the Middle East has invested in such an infrastructure and is developing a set of smart flows for key activities and workflows for its production operations, with the ultimate goal of improved asset performance.In response to early water breakthrough, a study was commissioned to investigate whether smart completions that use down-hole internal control valves (ICVs) could provide a range of fluid-flow control options to enhance reservoir sweep efficiency, reduce produced water, and increase well life. This paper describes the strategy and process to identify production and injection wells best suited for intelligent well completions in the Sabriyah field, Mauddud reservoir. The goal is to control zonal injection and production rates to reduce uneven water fronts, sweep and produce bypassed oil, postpone water breakthrough, and extend well life, thus boosting oil production while optimizing water handling at the surface. The study demonstrates excellent potential for down-hole control to significantly improve operations in the water injection areas.