Title page for ETD etd-11112009-204537

Type of Document Master's Thesis
Author Jin, Lu
Author's Email Address ljin1@tigers.lsu.edu
URN etd-11112009-204537
Title Downhole Water Loop (DWL) Well Completion for Water Coning Control --- Theoretical Analysis
Degree Master of Science in Petroleum Engineering (M.S.P.E.)
Department Petroleum Engineering
Advisory Committee
Advisor Name Title
Wojtanowicz, Andrew K. Committee Chair
Hughes, Richard Committee Member
White, Christopher Committee Member
  • water coning control
  • downhole water loop
  • water injection
  • anisotropy transformation
  • critical rates
Date of Defense 2009-11-05
Availability unrestricted
The Thesis is an analytical and numerical analysis of a new method for completing and producing oil wells affected by water coning. The method enables producing oil with no or minimal water cut while keeping the water subsurface with downhole water loop (DWL) installation. Typically, a DWL well is triple-completed in the oil and water zones with the three completions separated by parkers. The top completion produces oil to the surface while the middle and bottom completions drain from and inject into the bottom water zone, respectively.

Segregated-inflow operation of DWL well requires keeping the production and drainage-injection rates below their critical values. Therefore, the theory of water coning is re-visited and examined using analytical modeling of critical height and dynamic stability of water cone. The analytical model employs transformation from anisotropic to equivalent isotropic radial flow system. Also, considered are the effects of partial penetration and capillary-pressure transition zone.

The analytical model is used to determine operational domain of DWL for different well-reservoir systems. The results are then compared with data from commercial simulator and real field showing good match. Also investigated is the effect of the distance between water drainage and injection completions (D/I spacing), which is the most important design parameter for DWL wells. The results show that DWL wells could successfully work in reservoirs with relatively small aquifer as the DWL operational domain is only sensitive to small values of D/I spacing.

A commercial simulator is employed to build a numerical model of DWL operations outside the segregated-inflow domain where the top completion produces oil with water. The steady demonstrates the flexibility of DWL in controlling water cut. Then, the model is used to study DWL performance with controlled water production using a modified nodal analysis approach that includes the D/I spacing constraint. The results show that DWL could improve critical oil rate and reduce water cut before and after water breakthrough, respectively. Nodal analysis is used to seek the possible production operations of DWL which would help to design the D/I spacing and decide if one or two downhole pumps were needed for the system.

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