Unconsolidated reservoirs usually have poorly arranged sand formations. Consequently, produced hydrocarbon fluids may carry sand during the flow through screens to the surface. Unconsolidated sandstone reservoirs are highly prone to sand production, particularly during the initial stages of production, or when the reservoir pressure has dropped, or at the early onset of water. This sand production could lead to serious reservoir damage, adversely affect production, and reduce the potential production life of the reservoir. Common problems associated with sand production include erosion of downhole and surface equipment, collapse of the formation, and handling and disposal of the produced sand, particularly on offshore platforms. Operators around the world spend millions of dollars in sand cleaning workover operations.
In addition to current conventional sand control techniques, a novel sand control completion technology that uses a shaped-memory polymer (SMP) is actively deployed. When exposed to a catalyst, this polymer expands to conform to the wellbore sand face. The result is a porous and permeable filtration device that prevents the issues mentioned above and ensures production levels are maintained, maximizing the reservoir's potential. This outstanding technology offers a superior alternative to conventional sand control methods while reducing operational risk, cost and time by achieving total conformance and superior filtration on every job. The SMP is deployed in a compact state in the well and is activated by temperature and catalyst downhole to an expanded state that conforms to the shape of the wellbore. The SMP provides improved wellbore stability and efficient sand control, regardless of the wellbore irregularity across the formation sands in different reservoir zones. This technology can be considered for standalone sand control or used in combination with inflow control devices (ICDs), to ensure production optimization in a horizontal well.
Operationally, it is critical to ensure that the activation fluid used as catalyst for the SMP provides a rate of expansion best suited for field operations. For this particular application, it was also essential that the activation fluid should be non-damaging to the reservoir, compatible with the oil-based mud (OBM) drilling and completion fluids used to suspend the well, and operationally as well as environmentally friendly. Several fluid combinations were tested to identity the suitable catalyst that triggers the activation of the shaped-memory polymer and completes expansion at a rate desired for field operations. The optimum fluids are based on micro-emulsion technology that are environmentally friendly and able to activate the SMP fully within a stipulated amount of time (8 to 12 hours). The added benefits include breaking the oil-based filter cake and maximizing dispersion and flowback when the well starts producing.
This paper details the lab testing performed on SMP with various fluid mixtures and outlines the benefits observed using the mesophase fluid. This approach for improved sand control enables the operator to save all the workover-related expenses that are caused by sand production.
