Abstract
Many gas wells in unconsolidated sandstone reservoirs have been completed with stand-alone screens (SAS) that use either wire-wrapped screens (WWS) or mesh screens. This method is a cost-effective sand-control method for completions, especially in horizontal (Hz) wells where gravel packing (GP) may not be attractive for economic, operational, or logistical reasons. Because there are annular-flow failure concerns with this type of completion, a simple well-modeling study was conducted to look at the potential for application of inflow control devices (ICDs) to minimize annular velocity in Hz gas wells. This paper will discuss the annular flow results.
The purpose of the study was to investigate methods that could mitigate ‘hot spotting,’ a type of screen failure that can occur in an SAS completion, especially in high-rate gas wells. This type of failure occurs when fluid flow carrying abrasive particles is concentrated over a small area such that the entrance velocity is above the threshold for erosion. Swellable packers have been used to compartmentalize the SAS completion into many segments in an attempt to control annular movement of abrasive particles by minimizing annular velocity. However, the well modeling study discussed in this paper has shown that compartmentalization alone may not be sufficient.
This paper discusses the nodal-analysis software modeling tool that was used to build the well hydraulic models and to investigate the following flow behaviors:
Annular velocity
Effect of compartmentalization on annular velocity
Annular velocity in SAS-ICD completion
Effect of compartmentalization on annular velocity in SAS-ICD completion
Effect of ICD resistance on annular velocity
The study will show that 1) an SAS-ICD completion can be effective in minimizing annular flow, and 2), it appears to be the most effective means of minimizing annular flow in gas wells, ultimately reducing the chance of failure.
