Delivered the First Maximum Reservoir Contact Well in Giant Mature Field Using Source-Less LWD Technology; Case Study, Onshore Abu Dhabi

Abstract

This case study well is in a mature onshore field, which has been under production for a long time (started in 1970) resulting in depletion of some of the reservoir units presenting challenges for optimizing drilling performance and managing risks associated with stuck-pipe incidents. Additional challenges are minimized surface footprint, 100% reservoir contact in thin targets and acquisition of accurate petrophysical data for formation evaluation. A detailed pre-well study was conducted utilizing historical field and nearby wells’ data in the planning phase with close collaboration in a multi-disciplinary team including well and Bottom Hole Assembly (BHA) design and pre-well modeling for geosteering and LWD tool string configuration taking into account the elimination of radioactive chemical sources. The pre-well study has concluded that the azimuthal deep propagation resistivity image is going to provide proactive geosteering solution to identify the approach to both top and bottom boundaries. The BHA has also included rotary steerable system (RSS) along with optimized Logging While Drilling technologies (LWD) which has included, high-resolution micro resistivity imaging, Laterolog resistivity, nuclear magnetic resonance (NMR), sonic caliper and near-bit gamma ray. Continuous real-time monitoring provided drilling performance monitoring and analysis as well as facilitating geosteering services. The 8,356 feet horizontal section was effectively geosteered with 100% reservoir contact tapping into two thin reservoir sub-layers. Real-time azimuthal deep propagation resistivity image/curves were used to geosteer the well trajectory precisely within target zones and provided 4-5 feet TVD detection to bed boundaries. Also, high-resolution microresistivity images, dip picks and near-bit azimuthal gamma ray helped in maintaining the well-bore attitude parallel to the stratigraphy within each sub-layer. This data facilitated a smooth transition from one sub-layer to the next with minimum borehole tortuosity aided by the push the-bit RSS and at-bit-inclination measurements. In addition, NMR provided real-time porosity and permeability measurements assisting in well placement and enhancing reservoir understanding as well as optimizing future well planning workflows. This paper presents a step change from the traditional field development drilling techniques in terms of horizontal length. Similar well designs are currently being implemented in an effort to benchmark drilling, well placement and petrophysical data gathering requirements for future development drilling in order to maximize asset value.