Carbonate reservoirs hold more than 70% of the worldwide reserves. The knowledge related to the development of those reservoirs is not very developed due to the complexity of the lithology, the presence of post-sedimentation events such as diagenesis and the complex mechanical behavior. With the development of horizontal drilling in order to maximize the reservoir contacts (MRC), the need for accurate characterization of the horizontal variability of the mechanical properties of the rocks, becomes more critical. Classical 1D geomechanical models are no longer sufficient for the optimization of the drilling.
In this paper we address the issues mentioned above, through a 3D stochastic modeling of one of the critical parameters during the drilling of horizontal wells: The Formation Parting Pressure (FPP). This parameter allows the optimization of the mud-weight during the drilling of a well and optimizes the economic profitability of this well, while reducing the risks related to under or overpressure.
Three dimensional modeling of geomechanical parameters of the reservoir is an important task when dealing with drilling wells in carbonate reservoirs (Ait- Ettajer, et al. 2014)(Azim, et al. 2014). An inadequate calibration of drilling parameters such as mud weight, injection pressure might increase the cost of the drilling with a possibility of irremediable damaging of the reservoir. Classical approaches tend to build a one dimension geomechanical model along the well; however the current development of horizontal wells for optimal well sweeping requires a precise geomechanical model in three dimensions, especially for injection procedure in carbonates reservoirs with heterogeneous rock strengths distribution. We propose a workflow for assessing the critical parameters that impact the drillability and the economic cost of developing carbonate reservoir through horizontal drilling.
After a short description of the representation of the 3D reservoir model, we will describe the process of building the 3D model of Poisson Ratio using laboratory measurements and seismic volumes, and then we will describe the process for 3D assessment of the Fracture Parting Pressure parameter that will help optimizing the drilling parameters. We will show a case study of the application of the workflow for the optimization of the drilling in onshore carbonate reservoir.