The Jasmine Field is a mature stacked-sand oil field that has been on production since 2005. One of the biggest current challenges is to locate remaining oil accumulations. Seismic mapping, material balance and reservoir simulation studies provide pointers to promising locations, but can never guarantee accuracy. Pilot wells offer a means to appraise identified locations before committing to drilling horizontal wellbores. A pilot well is often used in Mubadala Petroleum drilling campaigns as part of an overall strategy to extend the field's life by continuing to locate and tap remaining oil accumulations. Collaboration across subsurface teams leads to decisions on pilot well locations. In most cases the pilot well appraisal objectives will be to confirm the structural position, to identify fluid contacts or to assess depth uncertainty, especially in areas where there is no well penetration or in significantly updip locations. These appraisal objectives apply to shallower and deeper horizons as well as to the target reservoir itself, and in Jasmine there is a strong record of accomplishment of successfully locating remaining oil by means of such appraisal. It is critical therefore, that well planning is tailored so as to accommodate the appraisal objectives as well as the eventual production target. Two case studies are presented, illustrating different approaches to using pilot wells prior to placing horizontal wellbores in Jasmine field. In the first case, the horizontal production wellbore was planned to develop an updip region of the target reservoir, to access remaining oil, with additional pilot well appraisal objectives in both shallower and deeper zones. The location for the new horizontal well was confirmed and this dual-role pilot/producer well not only succeeded in reducing depth uncertainty for the new horizontal wellbore, but also identified additional reserves in other reservoirs. In the second case an appraisal pilot well was used to investigate a downdip region of a depleted reservoir. Material balance assessment had indicated that the volume accessed by the updip producer was larger than suggested by the static model, which might have resulted in water encroachment from downdip, causing the appraisal location to water out. However, seismic imaging identified potential barriers between the updip and the proposed downdip appraisal location, which would have prevented water encroachment from downdip. The pilot appraisal well was required to distinguish between those two possibilities.

In many infill development scenarios, including those in shallow, heavy oil intervals, horizontal wells are required, and are positioned as high as possible within the reservoir. In other cases, horizontal wells are drilled to tap undeveloped oil in thin reservoirs with high uncertainty due to seismic resolution limitations. Mubadala Petroleum successfully deployed a new advanced Geosteering technology to overcome these technical challenges. Although Geosteering is often conducted in this Mubadala Petroleum Field, there was a need to mitigate the additional complications of well positioning in complex fluvial reservoirs using innovative approaches and technologies. The solution was a new multi-layer bed boundary detection scheme using a deep azimuthal resistivity distance-to-boundary tool. This was coupled with a novel sophisticated high definition stochastic seismic inversion, providing the ability to resolve multiple bed boundaries above and below the tool, clearly understand formation dip and improve understanding of the boundary azimuth angle. We present two case studies illustrating different applications of the new technology: The seismic inversion provided a clear image of the reservoir sand, however the new multi-layer bed boundary detection technology enhanced the ability to steer through the structural heterogeneous variations in the upper parts of the sand normally beyond seismic resolution of the data. The multi-layer bed boundary detection with high definition inversion provided valuable insight during the real-time horizontal drilling, which helped in maintaining the well in 75% high quality reservoir pay zone.For the horizontal drilling of the thinnest part of the reservoir where pre- and post-conventional seismic inversion volumes were insufficient to provide detailed stratigraphic and geometrical images, we successfully used the new technology to overcome the difficulties. In this approach and after landing the horizontal well into the sand, multi-layer bed boundary detection was used to navigate through the channel sand and maintain the well within the reservoir. This was assisted by streaming real-time high-definition stochastic inversion into the asset team's G&G software, which provided a highly accurate sand thickness, revising pay sand thickness from 15 feet to 25 feet and improving the accuracy of the volumetric estimation. As a result, the horizontal section was successfully navigated in 100% of the section and within high quality reservoir. Furthermore, we used this accurate data for a post-job recalibration of seismic and updating of the geological model and hence improving reserves estimation accuracy. This is the first Mubadala Petroleum implementation in this basin of multi-layer bed boundary detection and streaming high definition stochastic inversion, providing vital information to real-time execution and to post job improvement of the field model.

The development of marginal volumes in the Jasmine field is part of Mubadala Petroleum's overall strategy to extend the field's life. This development is accomplished by progressively exploiting increasingly challenging prospects. This paper highlights two case studies to illustrate how Mubadala Petroleum has successfully developed marginal prospects to unlock the Jasmine field's remaining potential. Prospect identification begins with integrated subsurface studies focusing on contingent resources. Several studies were conducted to determine the right technology to mature these marginal prospects. These prospects often involve the requirement to drill Extended Reach Drilling (ERD) wells. This is due to the fact that some platforms are slot constrained, such that wells cannot always be drilled from the nearest platform. One of Mubadala Petroleum's solutions was to drill a horizontal well with a completion that uses an Autonomous Inflow Control Device (AICD) to optimize and enhance oil production. This combination of AICD and ERD horizontal wells has proven successful in the Jasmine field's continuing development. Two wells in this case studies were drilled during the 2018 and 2019 drilling campaigns, illustrate how marginal volumes are developed in the Jasmine field, with each case having unique objectives and challenges. In 2018, one horizontal well was drilled, with an aim to enhance recovery efficiency in the viscous oil reservoir. The well was drilled close to the top reservoir, AICD devices were installed in conjunction with a sand screen to delay water breakthrough, and the well has been in production for two years. The overall strategy was effective in delaying water breakthrough. In 2019, a horizontal well was drilled to develop a relatively small 14ft oil rim below a thick gas cap reservoir. This well was the longest ERD well in the Gulf of Thailand. The well was also successfully drilled and geosteered at 4-5 ft TVD below the gas cap. AICD's were installed to balance the gas cap expansion and aquifer support to optimize oil production. The well has produced at a stable oil rate of 500-600 bbls per day with minimal gas and water production, up to the present date, confirming the validity of AICD technology in reducing the production of unwanted fluids. The AICD has been shown to play a significant role in optimizing production in reservoirs with small oil rims and thick gas caps. AICD completions also help to enhance production recovery from viscous oil reservoirs. Moreover, ERD drilling has improved the feasibility of several remote prospects and minimized the slot availability constraint in the Jasmine field.