An Integrated Solution in Drilling First Successful Horizontal Well in a Deep Carbonate Reservoir of North Kuwait
Authors: Rao Narhari S. , Al-Doheim Arif A.A. , Acharya Mihira N. , Al-Ajmi Neema H. , Al-Ajmi Saad A.H. , Kidambi Vijaya K. , Odreman Allan S. , Dashti Qasem M. , Haddou Hamid , Oyeyemi Oluwafemi S. , Chakravorty Sandeep , Chimirala Vivekanand 
Published: May 2016

As part of development of hydrocarbon plays of North Kuwait, the first horizontal well was planned and drilled within the deep carbonates (over 14500ft TVD) consisting of layered Kerogen and tight limestone (average 3pu and 0.1 mD rock), divided mainly into Upper (approx. 50ft) and Lower (approx. 30ft) reservoir zones. The well profile was designed to target multiple fractures and corridors for accessing the secondary porosity and consequently increase permeability which will enhance productivity and hydrocarbon recovery.

The main challenge in the effective development of this reservoir is the ability of the well to access the permeable interconnected vertical fracture network overlain by massive Kerogene at the top and water bearing carbonates at the bottom. In addition to this known challenge was the unexpected bedding dip changes due to local structural variations observed in the dip data of the borehole image logs in the pilot hole drilled just before horizontal lateral drilling. Natural fracture clusters encountered in the pilot hole were analyzed for orientation and extent. This helped in optimizing the drainhole trajectory to achieve the main objective of intersecting as many open natural fractures as possible.

A multidisciplinary team consisting of Well Placement, Geology, Petrophysics, Geophysics and Drilling utilized 3D seismic interpretation, real-time logging-while-drilling data from distance-to-boundary (DTB) resistivity mapping techniques, Gamma image coupled with Rotary Steerable drilling assembly and placed this first horizontal well, almost entirely within the target zone of fractured Carbonate section. Despite the challenge for real-time telemetry data transmission due to high predicted pressure regime, the team was able to achieve 90% NTG lateral through seamless integration. The well trajectory was revised in real-time as needed to overcome unexpected geological challenges encountered while drilling. The integration of real-time measurements, real-time decisions, interpretation and multidisciplinary approach was the basis of success of this project.

Introduction

Deep, sub-salt, tight unconventional reservoirs (average porosity of 3 p.u. and average permeability of 0.1 mD) are being targeted more aggressively for hydrocarbon potential. Till date, most of the wells have been drilled vertically or with some level of deviation through these reservoir zones with oil-base mud. The first horizontal well was planned and drilled at such great depths (over 14500 ft TVD) through alternating Kerogen-rich and carbonate formations after drilling a highly deviated pilot hole for formation evaluation and horizontal well planning. The well location was selected at a crestal area and the general direction of drilling the horizontal well was planned to be towards SW, knowing the regional trend of maximum horizontal stress direction is NE-SW. The main objective of drilling the horizontal well was to intersect the natural fracture systems extending through the target reservoirs and evaluate their potential of hydrocarbon production as an aid to develop the tight layered unconventional reservoirs.