This paper describes hydrate issues related to the design and success of a fast track development project for three Gulf of Mexico deep water subsea gas well completions. The project challenge required development of specific hydrate inhibition steps in order to minimize the occurrence of hydrates during well completion and flow testing due to cold mud line temperatures (45-55 F, 7-1 3 C)1 low reservoir temperatures (100-115 F, 38-46 C), and high bottom hole pressures (3,000-4,000 psi., 21-28 MPa.)
Basic hydrate formation theory and prediction were reviewed and integrated into a hydrate prevention program for the completion and testing program for this project. Hydrate prediction utilized temperature and pressure prediction modeling, overlay of potential events on hydrate equilibrium dissociation curves, and subsequent correlation to mud line temperature and pressure gauge measurements. Three areas of major concern for hydrate formation were during well flowback, shut-ins, and well kill. Hydrate inhibition included the use of inhibitors, and both surface and down hole injection systems involving various mixtures of glycol, methanol and IPA dependent upon the sequence of well events.
Oryx Energy Company undertook a rapid development or "Fast Track" program for two Gulf of Mexico (GOM) offshore blocks; 401 and 445, in the Mississippi Canyon (MC) area in 1993. The three well project, internally identified as the MC 400 project, was challenging in that the prospects were in a canyon area with water depths up to 2100 ft. (640 m) and would require a subsea completion with flowline tiebacks from 4 to 8 miles to the platform The low reservoir temperature of 100 to 115 F. (38 to 46 C.), cool mud line water temperatures of 45 to 55 F. (7 to 13 C.), the long subsea flow lines and the relatively high reservoir pressures of 3,000 to 4,000 psi. (21 to 28 MPa.) combined to make the control of gas hydrates a major design issue for the drilling, completion and flow testing of the wells.
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