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.

The Middle cretaceous Wara sandstone reservoir in Minagish Field is considered as highly heterogenetic sandstone which implying lateral facies extensive variations, stacked sand bodies with varying petrophysical properties. Several horizontal wells has been successfully drilled in lower part of Wara 6 sand channel, best thicker clean sand channel with very good oil production rate. Recently some wells have shown depleting of oil and increase water production. To develop such a challenging reservoir to maximize the oil production, a new plan has been developed to explore for new opportunities in Wara reservoir. The objective is to target different good stacked sand bodies in different Wara layers by drilling deviated wells. Some of old depleted Minagsih Oolite reservoir wells have shown good opportunities to sidetrack the wells into good Wara sand layers. This paper presents the integration between geostatistical models, well logs, well test results and different seismic elastic properties maps to identify best subsurface locations for drilling new deviated wells which combine the best quality sand bodies in different Wara layers. A few years ago geostatistical reservoir model along with core data and well log data were utilized to drill successful horizontal wells in W6 sand channels. However due to low resolution seismic data, Wara highly heterogonous lithology and uncertainty in geo-statistical model, it was challenging to continue identify good quality stacked sand bodies in different Wara layers without drilling unwanted silty sand or shale layers. Seismic inversion related elastic impedance data could discriminate between the good quality oil-bearing sand, shaly, and silty sandstones. Several old vertical wells that include good stacked sand bodies in different Wara layers; have been selected to validate the accuracy of elastic impedance maps along Wara layers.