An integrated framework for sand handling in wellbore and surface facilities

Abstract

Sand production affects over 70% of the oil and gas wells in the world. At higher production rates, the collision of the produced sand particles on the pipelines and fittings at an increased speed leads to material erosion. Over time, as the well's production rate decreases, sand deposition occurs in the wellbore when the fluid velocity drops below a threshold velocity for sand transport. Erosion can lead to equipment damage, and sand deposition can cause blockage. The oil and gas industries spend millions of dollars to control sand production. Such control techniques reduce production rates, thereby reducing cash flow. Alternatively, the co-production of sand and oil can increase the production rate and provide economic benefits if the risk and extent of sand production problems are minimized. Sand management techniques can be employed to determine the operating conditions under which production is high while the risks due to sand production problems are minimal. We developed a framework that integrates models of sand transport, erosion rate, and sand settling characteristics to tackle three major problems related to sand production: sand deposition in wellbores, erosional damage of pipelines and fittings, and sand accumulation in the surface facilities. This framework, SEAD (Sand Erosion, Accumulation, and Deposition), is implemented in a simulation environment to model sand production problems using the fluid properties from a wellbore simulation and user-defined solid properties. We employed the framework to study the effects of varying solid, fluid, and flow properties for different pipe orientations, fittings, and surface facilities as case studies. The results confirm that the risk of sand deposition is high for flow in horizontal pipes, and the erosion rate is high for the fittings such as tee, elbow, and choke. The framework was used to determine the operability range of a hypothetical wellbore to minimize sand deposition, erosion, and accumulation. The hypothetical wellbore produces fluid containing 10.5 m3/h of oil, 15 m3/h of water, and 4.5 m3/h of gas at 75 °C and 200 bar, and carrying 0.01 vol% sand of size 150 μm. Maintaining the production rate of the wellbore between 28 m3/h and 64 m3/h ensures at least 90% sand transport probability (STP) and keeps the erosion rate below 0.1 mm/year. It also keeps the sand accumulation in the separator over a week less than 5% of the separator height, which can be removed with weekly clean-ups.