Production Issues Influencing The Choice Of Completion Type In Horizontal Wells With Sanding Problems
Authors: Jones Colin , Cameron John , Owoeye Oladele , Baaijens Thijs 
Published: October 2008

The aim of this study was to examine wells in the same sand bodies in a field (designated as F1) in West Africa to determine which sand control completion option was the more efficient in a given situation, expandable sand screens (ESS®), external open hole gravel packs, stand alone screens and slotted/perforated liners.

The planned basis for comparison was to compare the productivity index per foot for each completion type. There were expandable screens, slotted and predrilled liner completions in the same sand body in the F1 field. The slotted and predrilled liners all had PLT logs from which to calculate PI values and the ESS well did not. The PI for the ESS well had therefore to be calculated using well inflow software. This then allowed a direct ranking of the PI/ft for each completion type. The ESS well had the highest PI/ft of the completions at 0.45 bpd/psi/ft; as compared to the slotted liners at 0.04-0.18 and the predrilled liners at 0.10-0.17. One other horizontal ESS well in a similar field (designated F2) was also used because it did have accurate PI information from a PLT log. This gave a PI/ft = 0.57 bopd/psi/ft which is similar to the simulated value for the ESS well in the F1 field.

Another aspect of the different completions is the variation in friction pressure between completion types such as ESS screens and EGP. The friction pressures in an ESS completion are lower than a typical EGP, standalone screen or slotted liner completion. This gives a very homogeneous inflow profile for the ESS completion due to the increased production bore. The EGP completion has a higher flow at the heel of the well; this accelerates water influx. The heel breakthrough time was calculated using an analytical model for the ESS and EGP completions for the F1 ESS well configuration. For the ESS completion, the predicted water breakthrough time was 191 days, which was close to the observed value in the well. The smallest EGP completion had predicted water breakthrough in 88 days.

Numerical simulations were also used to better understand water inflow and to test the assumptions in the analytical model. The simulations show a similar behaviour to the analytical model with water cresting up rapidly to the heel of the EGP well.

Introduction

Various completion options are available for horizontal wells in reservoirs with sanding problems. Cemented liners with perforations orientated in the direction of the greatest stress. This places the perforation in the lowest stressed region around the wellbore and can regulate sand production with limited drawdown. The process of cementing the liner can give a high mechanical skin due to formation damage and flow convergence around the perforations. Slotted liners (SL) can be used to maintain an open wellbore and control the sand production, but have a low open area and are hence more prone to plugging. The slot width is also a limiting factor as the slot size decreases the number needed increases to maintain the same open area.