Application of Advanced Mud Gas Analysis for Field Development: Kuwait Deep Carbonate Case Study

Abstract

Abstract

Kuwait Oil Company, as part of developing a deep multi-layered stacked carbonate HP/HT play (15000+ ft depth) in one of the northern fields, recently drilled a highly deviated well in a hitherto undrilled block. This part of the operating area is structurally complex, and a number of wells drilled previously in the vicinity encountered drilling complications due to losses. Further, estimating the reservoir base while drilling becomes challenging in this area due to multiple sub-seismic reverse faults encountered in the previous wells. Because of number of drilling and wellbore complications, full suite of wireline logs are sometimes missed out in these deep wells leading to an uncertainty in the formation evaluation. As a mitigation strategy to reduce this uncertainty, advance surface based mud gas acquisition and analysis was carried-out in this deep well. The analysis includes computation of several gas ratios which utilize gas components (C1-C8) & Aromatics (Benzene & Toluene) within the mud. Gas components are continuously extracted from the drilling mud and monitored at the rig site, using the advanced gas extraction system. This data is transmitted to the asset team, for integration with the geological models. This data, in addition to giving an understanding of the prospectivity of the play while drilling, supported the subsequent formation evaluation process by a. highlighting the main zones of interest, b. qualitative fluid characterization, c. reduce uncertainties in interval selection. Early indications of the prospectivity of this block is very useful for further development planning. An advanced X-Ray Fluorescence(XRF) workflow at rig site was also applied in this well. This analysis is based on measuring major and minor chemical mineralogy elements of the drilled formation. This has helped in better qualitative assessment of different facies such as limestone, dolomite, shale etc., and providing a better control on geological model update while drilling the well. Using this information, it was possible to carefully decide the final drilled depth of the well and secure the well without further drilling compilations. Through this process, asset team could decide on assessing the base of the reservoir before acquiring the open-hole logs and calling the final drilled depth without affecting the well objective. Based on this lead, advanced mud gas analysis workflow is increasingly being deployed in other development wells in these fields.

AAPG Datapages/Search and Discovery Article #90260 © 2016 AAPG/SEG International Conference & Exhibition, Cancun, Mexico, September 6-9, 2016