Mechanism of oil and gas wells and sand hazards

From the rock mechanics point of view, there are two mechanisms reservoir sand : the shear failure and tensile failure mechanism . In addition to these two mechanisms , but also includes a maide Coal seam gas particle migration mechanism .Shear failure mechanism . As the rock near the wellbore and perforations suffered circumferential stress and radial stress is too large , causing the rock shear failure , causing formation sand .Tensile failure mechanism . When mined , the friction stress around the maide frac proppant fluid gradient and under the action of carrying rocks to withstand tensile stress when this stress exceeds the tensile strength of the rock, the rock tensile failure .Sand particle transport mechanism . In production, the production of pressure or excessive production , acting on the formation of particles too large to pull the drag force , will move particulate formation , leading to decreased formation permeability around the bottom , thus increasing the drag of the fluid drag force , and solid particles may induce output .Sand hazards mainly in the following areas: reduction or stoppage, abrasive surface and downhole equipment , casing damaged wells scrapped , lost production time, the economic and technical losses such as oil and gas wells .