Installation of sand filters in reservoir intervals represented by unstable rocks

Relevance. Need to prevent the collapse of hydrocarbon reservoirs composed of weakly cemented rocks, to support the bottomhole zones of wells completed in weakly cemented rocks, and to clean formation fluids of sand. Aim. This work is devoted to ensuring reliable filtration, preventing rock flowback, maintaining reservoir permeability for oil production, and stabilizing the bottomhole of oil wells drilled in weakly cemented rocks. Objects. A set of downhole equipment and process "objects" is used that provide both mechanical filtration and wellbore stabilization: the main element, consisting of a perforated base pipe and a filter shell (wire winding, multilayer mesh or metal-ceramics), pre-packed filters (a layer of resinous or ceramic gravel is already placed between the mesh layers), gravel (calibrated quartz sand or synthetic material pumped into the annular space between the filter and the formation), a gravel packer, which isolates the flushing interval from the rest of the well. Methods. In an open hole, the filter is lowered into an uncased interval, after which the annular space is filled with gravel. In a cased hole, the filter is installed inside the column opposite the perforations. Gravel is washed both into the annular space and into the perforations themselves for their stabilization. A hybrid method combining hydraulic fracturing with gravel packing, allows you to create a highly conductive fracture filled with gravel, which minimizes the skin effect in poorly cemented rocks. The expandable filter consists of a packer secured to a short branch pipe from the casing pipe, connected to the liner. The packer is activated by the pressure of the drilling mud (water or other liquids) within the range of 5, 20, and 30 MPa. The design pressure is reduced as the gap between the packer and the wellbore wall increases. The packer diameter (89–340 mm) is 31.7–85.7 mm larger than the diameter of the pipes, on which they are lowered. Results. The author has developed the method for producing gravel filters for vertical, deviated, and horizontal wells. This method enables the design of high-quality gravel filters with high continuity and density of gravel filling along the entire length of the frame. To obtain dense gravel packs, specially developed rectangular branch pipes installed on the outer side of the filter elements are used.