A Collaborative Approach in Horizontal Drilling for Well Cost Optimization and Optimum Drainage, Minagish Field, West Kuwait

Abstract

The Cenomanian Wara Formation in Minagish Field is composed mainly of coastal plain deposits, observed at field scale along with shallow marine shales and carbonate bioclastic sandy beds. They are locally disrupted by embedded channelized sandy bodies from fluvio-tidal origin. The reservoir units are represented by different channel geometries with limited areal extension. The placement and completion of horizontal and highly deviated wells in such reservoir is a challenge necessitating a collaborative approach to avoid major well bore instability issues. These issues have a significant impact on the well cost and time line. In addition, having the right placement and completion is important for optimizing the drainage contact. To address such challenges during the different stages of the drilling operation, different technologies were used. For example, while the well was drilling through the unstable Wara and Ahmadi shaley formations, a Logging While Drilling (LWD) sonic and gamma ray (GR) tools were used to update in realtime a predrill geomechanical model with the formation acoustic and GR properties. Having such measurements allowed calculating the right mud weight density which resulted in drilling a stable borehole. This was confirmed by the absence of cavings and tight spots thought out the whole operation. On the other hand, the drain section was drilled in Wara channel sands which are known to be composed of a thinly bedded faulted sand-silt sequence with the sand layers being relatively radioactive. To help steering in such complex environment, a combination of LWD tools were chosen to place the well in the sweet spot of the target. These tools involved using the advanced deep azimuthal resistivity (geosteering) and the Multi-Function LWD (advanced petrophysics) tools. As a result of this, the horizontal section was proactively geosteered in the reservoir in which 1049 ft MD were steered in the high-quality sand layers.