Mitigation of Sand Production Risk Using Thermally Expandable Polymeric Beads
Authors: Han Yanhui , Liang Feng 
Published: October 2022

Sand production is nearly always detrimental to the short- and/or long-term production of the well. It can present major obstacles to well production through reduced production rates, sand bridging, erosion of equipment, and sand disposal and removal. In this work, we introduce a new concept of using thermally expandable, high-stiff polymeric beads as gravel pack materials, either replacing the regular gravel sand pack partially or fully to fill the annulus between production tubing/slotted liner/screens and reservoir to compensate the high stress near the wellbore during sand production. Under the reservoir condition (treated with bottom hole temperature), these polymeric beads will expand in volume. The volume expansion of gravel pack materials in the annulus space will result in additional mechanical pressure against the wellbore, which will subsequently decrease the hoop stress and increase the radial stress in the near wellbore region; therefore, the mechanical failure and the risk of sand production can be reduced.

1. INTRODUCTION

Weakly consolidated sandstone reservoirs with permeability in the range of 100 md - 10 Darcy are most susceptible to sand production. The solid material produced from a well can consist of both formation fines and load bearing solids. The critical factor to assess the risk of sand production for a particular well is whether the production of the load bearing materials can be maintained below an acceptable level at the anticipated flow rates and if the producing condition will make the well production acceptable. There are a few factors influencing the tendency of a well for sand production, such as degree of consolidation of the formation, production rate of the reservoir fluids, pressure drawdown, reduction of the pore pressure, reservoir fluid viscosity and the volume/amount of water production.

Sand production is nearly always detrimental to the short- and/or long-term production of the well. It can present major obstacles to well production through reduced production rates, sand bridging, erosion of equipment, and sand disposal and removal. The sand control methods can be classified into two major ways: mechanical and chemical. Mechanical methods of sand control prevent sand production by stopping the formation with liners, screens or gravel packs. Chemical control methods involve injecting resins into the formation to consolidate the sand grains. Gravel pack completion relies on the bridging of formation sand with larger well-sorted sand pack which have been retained by a slotted liner or screen. The size of the well-sorted sand pack is typically 5-6 times larger than the formation sand. Gravel pack creates a permeable downhole filter that will allow the production of the formation fluids but restrict the entry and production of formation sands. In this type of completion wells, the reservoir fluids flow through the sand pack into the wells. In the near wellbore region, the stress concentration is high and the confining stress and pore pressure inside the wellbore are low, so rock mass can easily run into mechanical failure, which can significantly reduce the compressive confinement stress on the solids in the solid matrix.