Development and Assessment of Well Control Procedures for Extended Reach and Multilateral Wells Utilizing Computer Simulation

An assessment of the state of the art in well control for extended reach and multilateral wells has been developed by completion of four inter-related tasks described as follows:

Task 1 – Perform a literature search of the state of the art in well control for vertical, directional, horizontal, extended reach, and multi-lateral wells.

Task 2 – Modify an existing Windows-based well control simulator that has been developed for use in more conventional wellbores to model extended reach and multilateral wells.

Task 3 – Use the simulator to evaluate, compare, and contrast the current well control procedures utilized for vertical, directional, horizontal, extended reach, and multi-lateral wells.

Task 4 – Based on the results of the simulation study, recommendations had been made to improve well control for any situations that warrant improvement, especially for the extended reach and multi-lateral wells.

Other phenomena that needed to be studied and compared are as follows:

1.  Kicks without drill pipe in the hole (or laterals);

2.  Kick migration in multiple laterals and near horizontal wellbores;

3.  The effect of the compressibility factor, z, on casing and drillpipe pressure;

4. The effect of the compressibility of the drilling fluids and formation.

Task 1 – Literature review – completed.

Task 2 – Modification of conventional well control simulator to model ERD/ML wells, the following had been completed:

-        Five model programs had been reduced and rearranged to three modules for effective programming and file management,

-        Modification of the updated simulator to save and open input data,

-        Modification and improving well control simulator tin Visual Basic vs. 6 to handle multilateral (ML) trajectories was finished.

Complete kick kill simulation has been modified. However, complete kick kill simulations for conventional and extended reach trajectories are available as before.

Task 3 – Use of simulator to compare and contrast well control problems. More than 350 simulations covering a wide range of wellbore trajectories for extended reach wells have been completed. The runs cover a wide range of kick-sizes in wellbores ranging from conventional wells to extreme extended reach wells in ultra-deep water with different circulation rates. A literature review of multiphase flow behavior and flow patterns expected in horizontal fully eccentric annuli was completed. An evaluation of gas displacement in horizontal wellbores has been completed to determine the most efficient flow velocities to remove all the gas from the lateral section of wells. The multilateral simulator is being used to complete a parametric study to determine the effect of kicks and kills on multiple open laterals as well as the effect of the multiple laterals on kicks and kills.

Task 4 – Recommendations – Recommendations for improvements in well control had been completed based on the results of the tests and evaluations completed in Tasks 1-3.