This dissertation focuses on the nitrogen drilling problems, gas-lift drilling technique, and hydraulic fracturing problems in shale reservoirs.
The performance of nitrogen drilling is very unpredictable because of limited knowledge of gas-rock interactions. Complete analysis of gas-rock interaction requires an accurate model to predict gas temperature profiles. The current mathematical models are not suitable. A new analytical solution for predicting gas temperature profiles inside drill strings and in the annulus is derived for nitrogen drilling, considering the formation fluid influx, Joule-Thomason cooling effect, and entrained drill cuttings.
The new technique, called gas-lift drilling, has been proposed to solve some problems hindering the application of conventional drilling. A technical assessment of gas-lift drilling is carried out to determine the feasibility of this technique. It is found that, compared to conventional gas drilling, gas-lift drilling can reduce gas injection rate required for hole cleaning by at least 70%. The kick-off pressure for unloading the well can be lowered by reducing valve spacing. The gas injection pressure in gas-lift drilling will be in the same level as in conventional gas drilling. The gas-lift valve can be designed to open and close automatically depending upon the water-induced pressure inside the drill string. The gas-lift valve design experience gained from artificial lift can be employed in gas-lift drilling. In this study, it is concluded that gas-lift drilling has the potential to become a viable and feasible technique for development of unconventional tight oil and gas reservoirs with improved performance and reduced cost.
For hydraulic fracturing, some of the proppant is produced back into the wellbore during the flowback process. Post fracturing flowback procedures are critical to the production performance of fractured wells. The success of hydraulic fracturing partially depends on retaining proppant in the fracture during the flowback stage. The objective is to determine the critical flow rate that will initiate proppant production during the flowback process. The critical flowback rate for controlling sand production has not been adequately investigated. This dissertation comprises experimental investigations of the critical flowback velocity in simulated fractures in shale, filled with different proppant sizes under various confining pressure conditions.
|Commitee:||Feng, Yin, Gang, Daniel, Hayatdavoudi, Asadollah, Seibi, Abdennour|
|School:||University of Louisiana at Lafayette|
|School Location:||United States -- Louisiana|
|Source:||DAI-B 80/08(E), Dissertation Abstracts International|
|Subjects:||Engineering, Petroleum engineering|
|Keywords:||Gas drilling, Gas-lift drilling, Heat transfer, Hydraulic fracturing, Shale reservoirs|
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