Historically, computers have been used to perform the initial design for primary cementing. Little has been done with the "Second Phase": on-site verification.
The "Second Phase" involves using measured data obtained on site to optimize the initial (or "First Phase") computer design. This "Second Phase" can eliminate many of the unknowns that are present with the majority of the primary cement jobs done today.
This paper illustrates how on-site design verification, coupled with post-job analysis, is used toimprove the success rate of primary cementing operations. Computer monitoring and modeling, while circulating, can often detect potential problems prior to cementing. At this point, the design parameters are modified, and the design program is re-run on location.
A change in mud rheology, or a restriction in the annulus, may result in increased downhole pressures creating lost circulation problems. By comparing measured circulation pressures with those predicted with an on-site computer model, these types of potential problems can be detected. The actual cause of the pressure discrepancy is found by the process of elimination. After the problem has been isolated, the job is modeled using corrected mud or hole conditions. If lost circulation, gas migration, or poor mud removal is indicated, corrective measures may then be taken.
A checklist of data needed for pre-job simulation is presented along with a discussion of how thisinformation is used. Benefits of realtime monitoring are discussed, including examples of corrective actions taken.
The intent of this paper is to show the benefits to be gained with pre-job simulation and post-jobanalysis.