Workflow to Evaluate Maximum Allowable Treating Pressures, Tubing Movement, and Tubular Limits for Deepwater Subsea and Dry-Tree Fracpacks

Abstract

Deepwater wells using fracpack stimulation are progressively moving to ultradeep water depths and total depths; the bottomhole pressures (BHPs) and temperatures of future reservoirs could exceed 20,000 psi and 250°F. To safely perform deepwater fracpack treatments, the following pressure and tubular limitations should be considered:• Maximum surface tubing pressure because of pipe limitations and gravel pack assembly component ratings.• Maximum surface annulus pressure because of blowout preventer (BOP) ratings.• Maximum allowable tubing movement while pumping to help prevent premature job cessation.• Maximum allowable downhole slackoff and overpull because of well path, pipe, pipe connections, and downhole component ratings.Depending on the well depth, pressure, temperatures, and BOP type (subsea or dry-tree), various pipe, connection, or equipment limitations might be exceeded during multistage fracpack stimulation operations. Initial pipe loading as well as pre-fracpack stages, such as the pickle, acid treatment, or minifrac calibration treatment, will alter the pipe failure and movement conditions and must be accounted for in the final completion design.Because of these concerns, a workflow process has been delineated to evaluate the maximum allowable treating pressures, tubing movement, and tubular limits for deepwater subsea and dry-tree fracpacks across four components:• Input component to consolidate well and stimulation data for further workflow analysis.• Surface treating pressure evaluation component to analyze certain treating pressure limitations.• Commercial wellbore, casing, and tubing simulator to evaluate work string safety factors, tubing movement, and downhole forces. • Commercial torque and drag simulator to evaluate surface slackoff requirements and allowable work string overpull.A description of the variables, range of values, and other considerations for each of these four components is discussed, and the benefits of using this process to evaluate fracpack stimulation are shown. Well case histories are also used to support this process.