Strategy for Drilling IceCube BoreHoles Agenda Statement of Problem



Yüklə 1,55 Mb.
tarix02.10.2018
ölçüsü1,55 Mb.
#71744


Strategy for Drilling IceCube BoreHoles


Agenda

  • Statement of Problem

  • Assumptions

  • Approach

  • Analysis

  • Results



Statement of Problem

  • Hot water jet is used to melt ice – drill a hole of a specified diameter - ice starts to refreeze back!!

  • Use knowledge of freezing process to predict the expansion and contraction of the hole – and develop a Drill Strategy to minimize the total fuel consumption, leaving a sufficient diameter of hole for String Deployment.







Approach

  • Extension of Simulation based on Study done by Neil Humphrey and Keith Echelmeyer on “Hot Water Drilling and Bore-Hole closure in Cold Ice”

  • FORTRAN Code was developed on the above analysis :

  • a) Provided in part by Echelmeyer

  • b) Modified as per our requirement (to include reaming, instantaneous melting)

  • Compare the output of the simulation with actual AMANDA/ICECUBE data

  • Results



Newt-Koci Parameters

  • 88 C, 200 gallons/min

  • The Heat Available at the Nozzle is 4.65 MW and it decays with depth z as

  • Temperature profile of Ice

  • After Initial Radius has been drilled, the temperature of the water sitting here decays with . Verified with AMANDA Data.



Finite Difference Solution



Temperature Profile

  •  

  • This is the temperature profile we use as an input to our program and note that the temp at the very bottom is close to –20c and at the top is close to –50c

  •  



Strategy for Baseline Model

  • Summary:

      • Inputs:
          • Lambda: 8000 m
          • Water Temp. at surface: 88 C
          • Flow Rate: 200 gallons/min
          • Surface Power: 4.65 MW
          • Deployment Time: 30 hrs
          • Target Diameter: 45 cm
      • Outputs:
          • Drilling Time: 19.06 hrs
          • Ream Time: 12.36 hrs
          • Total Energy Deposited: 538 GJ


Optimal Solutions

  • a) The solution to this problem requires a non-linear optimization of the drill rate, time of heating, and the borehole closure rate. This optimal solution produces a drill speed that leads to a targeted uniform diameter for a target deployment time. In this case, no extra heat would be applied nor any time wasted by drilling too large a hole at any depth, which is the goal of the smart drill.

  • b) We started out with very high drill and ream speeds, and decreased the drill speeds until we met the requirement of the drill fitting through the new opening. At this drill speed check whether or not we met the requirement of the target diameter after a fixed deployment time. If we met the required deployment time, we chose those speeds as part of the drilling strategy. We carry these values to the next slice, obtaining the heating time for this slice by subtracting the total heating time from the time available for the previous slice. If at the bottom of the hole there is not enough time for heating, we repeat the process, spending more time inside the hole.



Drill/Ream Strategy



Time Spent by Drill Head



Temperature In Surrounding Ice



Energy Deposition



Diameter – Refreeze Back



Transformation of Hole Size





Hole 49 Refreeze (Actual Data VS Simulation)



E-mail Confirmation

  • Date: Wed, 3 May 2006 00:02:46 -0500 (CDT)

  • From: Mark Krasberg

  • To: Newt Ganugapati

  • Cc: Bob Morse , Albrecht Karle , Kael Hanson kaeld@icecube.wisc.edu

  • Subject: Re: my predictions for hole 49 closure

  • Newt

  • It is May 2nd, which i believe was the day of your freeze-in prediction.

  • as luck would have it, i am logged in to the pole.

  • and guess what: 49-55 "Fusilli" has frozen in!

  • I actually dont know what the scaler rates were for the last couple of weeks, but the fact that it has now frozen

  • in, in my opinion, makes your prediction a success.

  • eventually we will pin down more precisely when the freeze-in occured...

  • thanks,

  • mark



Icecube Season Performance



Perturbation Analysis

  • Hose Characteristic (Lambda)

  • Deployment Time (w.r.t Baseline Model)

  • Final Diameter



Summary – Perturbations on Lambda



Summary – Perturbations on Deployment Time



Summary – Perturbations on Final Diameter



Summary Of Perturbation



Summary & Conclusions

  • We have developed a robust toy/tool that would help the optimization of energy required for boreholes drilled using the thermal techniques

  • This has been developed before the drilling season for IceCube holes and the data compares well with what was forecast

  • submit a publication to journal of Glaciology

  • http://www.icecube.wisc.edu/~newt/drillbigreport.doc



Yüklə 1,55 Mb.

Dostları ilə paylaş:




Verilənlər bazası müəlliflik hüququ ilə müdafiə olunur ©genderi.org 2024
rəhbərliyinə müraciət

    Ana səhifə