--> Drilling Success Utilizing Advanced Horizontal Geo-Steering Techniques To Develop Thin Reservoir Channels Boosting Declining Production. Thinner, Further Faster.

AAPG Asia Pacific Region GTW, Back to the Future – The Past and Future of Oil and Gas Production in the Asia Pacific Region

Datapages, Inc.Print this page

Drilling Success Utilizing Advanced Horizontal Geo-Steering Techniques To Develop Thin Reservoir Channels Boosting Declining Production. Thinner, Further Faster.


Objective Wassana oil field, situated in the Gulf of Thailand Block G10/48, was developed by KrisEnergy in 2015/16 utilizing 10 slant wells and 5 horizontal wells. The Wassana 2017/18 infill well program comprised six horizontal wells that were successfully drilled with maximum lateral reservoir exposure enabling the production boost to the field, these six wells currently contribute 64% of the field current daily oil production. This presentation will share details of the campaign’s placement of the horizontal wells. Methods/Process Horizontal well execution faced several difficulties for well placement execution. First, insufficient well control brought depth uncertainty of target reservoirs for most of the planned horizontal wells. Secondly, the local structural dip couldn’t be identified accurately from the seismic data creating difficulty to optimally land the well in the reservoir. Lastly, lateral sand continuity, thickness (for example one well targeted a 7-foot vertical thick reservoir) and reservoir quality were the main challenges for horizontal geo-steering. Therefore, the ultra-deep resistivity geo-steering technique was chosen to achieve the well objectives, overcome challenges and minimize the uncertainties to place all the horizontal wells for this campaign. Results/observations The table above illustrates the drilling program results with the average of reservoir net to gross ratio is 94%. Compared with the 2015/16 campaign this represents a 3% increase in geo-steering length and 7% increase in ROP. This resulted from collaboration between geoscientists and well placement engineer to integrate all the available data (seismic data and offset well petrophysical data). The geo-steering process began with pre-drill modeling, through real-time execution and post-drill evaluation. The well results, extended lateral sections, greater net to gross, proved the effectiveness of the chosen horizontal geo-steering technique. The ultra-deep resistivity tool mapped sandstone attributes for real-time horizontal geo-steering such as, the distance to the top and base of the sandstone reservoir, sand thickness, structural dip of the strata and sandstone layer quality. All this information contributed to the lateral completion design success and consequent well productivity contributing to increases in the field oil production. Novel/Additive information Developing thin sandstone reservoirs in the Wassana field by innovative use of well placement technology has demonstrated the correct strategy to further develop the field by overcoming the reservoir continuity and thickness limitations, meeting drilling objectives and arresting field production decline. Also, it showed that the small oil pools could also be successfully exploited economically. The success story has become a model of field development optimization and it will be applied widely.