Real Time Geosteering of High Tech Well in Virtual Reality and Prediction Ahead of Drill Bit for Cost Optimization and Risk Reduction in Mumbai High L-III Reservoir

Abstract

The Geosteering of high tech horizontal wells through thin reservoir sections is always a challenge. If the entire operation of real-time LWD Geosteering is monitored in a virtual reality environment, a near reality wellbore drilling situation can be simulated through stereoscopic projection within a modeled reservoir for better understanding and interpretation of a complex problem. This has significant benefits in reducing the rig wait time for critical decisions. Additionally, it provides the tremendous advantage of using the expert multi-disciplinary team at the base thus reducing the risks of drilling a less than optimal well. The Mumbai High L-III reservoir is a highly heterogeneous multilayered carbonate reservoir on the continental shelf of western India in the Arabian Sea. As a part of ongoing redevelopment program, multiple horizontal wells are being drilled through thin productive layers. This paper describes a successful Geosteering application using the latest technologies to transfer, edit and analyze information in real time. Real-time LWD data were transmitted via the INSAT 3B satellite from the offshore drilling rig to the Virtual Reality Centre in Mumbai City, India. Seamless sharing of data between the service company and the Reality Centre was achieved using the recent WITSML 1.2 data transfer standard. Real-time LWD, seismic and drilling data were integrated to monitor the drilling progress. A pre-defined geological model was used to model the LWD data. The planned and actual well trajectories were continuously updated while drilling. The geological model was updated based on the comparison between real-time and modeled logs. Instructions regarding mid course corrections were conveyed to the drilling engineer at the rig. The technology helped to optimize the well path, maximize the productive interval and avoided unproductive rig time. Introduction Mumbai High is one of the most complex oil and gas fields in the world as well as the largest and most prolific in India. It is located about 160km from Mumbai City in the Arabian Sea on the continental shelf. The entire field is divided into two areas, Mumbai High North and South, separated by a low permeability barrier. The field has multi-layered reservoirs with the L-III carbonate the main producer. The production from the field commenced in 1976 and it has been produced 20% of initial oil as on today. The field is at a very mature stage of its life cycle. In order to accelerate production and improve the recovery factor, a detailed redevelopment plan was formulated where a large infill drilling program was planned to drain the bypassed oil with several dual producer and injector wells. The study area falls at the boundary of the gas cap in Mumbai High North where the upper stacks of L-III are gas bearing and lower stacks such as L-III-h are producing oil. The paper deals with a real time operation and model update techique in a virtual reality environment applied to a high tech well with a 700m planned drain hole. The well targeted the 6m thick L-IIIh layer which had an effective porosity of 22%. The LWD Geosteering data was acquired by a major drilling service company and was transmitted through INSAT 3B to the server at the Virtual Reality Centre. Using WITSML 1.2 (Ref. 1 & 2) the real time data was then streamed into the modeling packages to update and monitor the drilling process. The planned and actual well paths and the modeled and actual logs were presented in the 3D stereoscopic projection and on the seismic volume to be validated and interpreted by the multi-disciplinary team. Instructions were conveyed to the offshore drilling rig to incorporate mid course corrections. The main objective of this project was to geosteer the well through the thin carbonate reservoir using a virtual reality environment to make faster and smarter decisions. This helped to reduce rig wait time and maximized the chances of a successful well. Core Study and Electrofacies A detailed core study indicates the presence of Foraminiferal packstones and wackestones as the dominant microfacies in the L-III reservoir. These were inter-layered with calcareous, carbonaceous and nodular shales in most of the area. The porosity development is mainly secondary in nature, however primary porosity has been reported at places in coral fragments and in the matrix.