A Field Proven Analytical Method to Resolve the Open Hole Volume Gravel Packed in a High Angle or Horizontal Well, Enables Enhanced Pre-job Simulation.

Abstract

Abstract This paper demonstrates an analytic approach to measuring the success of horizontal, open hole gravel pack completions. The approach is discussed using five UK North Sea case histories in which a post job evaluation was used to determine the percent of the open hole successfully gravel packed in each well. The method was verified in the field using radioactive tracer and / or temperature logs in three of the five wells with 3000 ft to 5000 ft horizontal open hole sections. The method closely estimates, without intervention, the actual Effective Open Hole Diameter, Deff, following drilling and hole clean-up operations. Using Deff, the observed Alpha Ratio, and an iterative match point technique, the actual lengths of the open hole gravel packed were computed. The method also corrected existing simulation procedures for calculating the volume of sand placed in the cased section above the sand control screens. During the pre-job planning or simulation phase, an incorrect estimate of open hole diameter can result in erroneous estimates of transport velocity, dune height ratio, minimum pump rates required to avoid sand duning in the work string, the Alpha and Total Pack Time, and the sand and slurry volumes required. In addition, the relative success of the gravel pack could not be correctly measured, using previous methods where only the theoretical open hole diameter and measured sand slurry volume were known. This proven Alpha Ratio analytical method provides an insight to the actual Effective Open Hole Diameter, enabling continuous improvement through enhanced pre-job simulation of subsequent project wells.