Abstract
Abstract
The Wara sandstone reservoir in the Minagish field of Kuwait Oil Company is a complex deposition of a typical pro-deltaic environment consisting of shaly-silty sandstone sequences W7-W1. Three sequences (W6, W5, and W3) were expected in the case study well. The objective was to set 9⅝-in. casing at the top of W6 and then drill through the Wara sequences to connect all of them and land and drill the lateral section within W3.
The W6 sequence is typically the primary target in the Wara formation, being thick and consistent throughout the field. The next logical step in developing the Wara reservoir was to study and investigate the minor W5 and W3 members. Due to poor correlation of W5 and W3 channels in offset wells, the geological target was selected based on seismic Poisson impedance. Historically, targeting the Wara formation occasionally resulted in multiple sidetracks due to drilling challenges. A real-time geomechanics service was utilized to overcome drilling challenges and real-time 3D ultra-deep resistivity inversion was implemented to optimize well placement.
An extensive pre-drilling study for geomechanical and ultra-deep resistivity inversion modelling helped to develop road map for an optimal and safe well-construction process. The study showed that utilization of real-time 3D ultra-deep resistivity (UDR) inversion would help to optimize well placement and maximize sweet-zone exposure. The original well design, mud properties, and drilling parameters were modified based on the geomechanical study. Additionally, real-time geomechanics services were utilized to monitor and control the drilling process to follow the road map, which helped to avoid drilling issues, geostop at the W6 channel, and finally to run the casing smoothly. Real-time 3D ultra-deep resistivity mapping in the lateral section helped the operator to drill through W6 and W5, land precisely, and drill the lateral in the W3 channel, which was well developed, as expected from seismic Poisson impedance analysis. Formation evaluation of lateral section showed an average porosity of 24 p.u., water saturation 11% and up to 3 D/cp mobility.
The application of real-time 3D ultra-deep resistivity inversion helped to triple the planned formation exposure and to discover a geometric extension of the above deposited channels (W6 and W5), which will help for future field development. The flow test showed the highest production rates from W3 of the field. The integrated approach described above was recommended to be utilized for all future Wara wells.