In 2011 eni developed the residual reserves of some of their Italian carbonates oil-fields, drilling horizontal wells employing innovative methodology and field testing Logging While Drilling technology.
To improve the original planned oil recovery and production it was introduced the proactive geosteering technique; the technology by which the well trajectory is verified and modified in real time in order to optimize well placement. The eni Italian northern district (DICS) has developed a distinctive methodology where well data are continuously interpreted and compared to the geological model in order to maintain the well path within the target formation. This methodology is the outcome of geosteering activity during the last three years in gas storage fields (for Stogit). After an accurate pre-job modelling, the most advanced Logging While Drilling devices were employed to optimize the drain sections. Real-time resistivity images and distance to boundary detection were among the most used measurements that allowed initially penetrating the target in the optimal structural contest and afterwards keeping the rotary steerable system within it. The acquired data were integrated in a software platform with dedicated well placement plug-ins to facilitate the interpretation and the critical decision making process.
The paper summarize the successful placement of multiple drain holes immediately below the caprock, through proactive geosteering, improving attic oil recovery and increasing distance from oil-water contact. This innovative experience allowed in one particular case, adding 1.25 Mboe of attic oil and providing a well production ca. 35% superior to sub-vertical offset well.
