METHOD TO PREVENT WELL SANDING USING GRAVEL PACKING

Description

FIELD OF INVENTION

This invention is related to methods of well sanding prevention, particularly to the technologies of gravel pack making, and may be used for underground formations treatment, particularly for operations to prevent sand inrush from the oil formation into the well.

Gravel packs are used to prevent well sanding. A typical operation for filling the pack with gravel is installation of a mesh filter in the well and placement of gravel between the filter and perforated casing string. The gravel prevents sand inrush from the reservoir into the well and formation fluids are filtered into the well through the gravel and mesh filter. The gravel pack may also be applied without installing the pack into the well.

DISCUSSION OF RELATED ART

Methods of well sanding prevention using various gravel packs are known. Possible solutions are claimed in the following patents:

• • 1. U.S. Pat. No. 7,255,168, this patent discloses a method of underground formation treatment, namely,—a method to prevent well sanding by delivering gravel pack into the well, the gravel pack is a homogenous mix of polyethyleneterephthalate (PET) and filler. The filler may amount to approximately 5% to 70% of the entire mix weight. It may be various particles compatible with thermoplastic material, e.g. coenospheres, microspheres, ashes etc.
  • 2. U.S. Pat. No. 7,281,580, this patent discloses a method of gravel pack making using adhesive-coated high-density plastic particles.
  • 3. GB2436011, this patent discloses a method of well sanding prevention using polyamide particles. The main disadvantage of this method is low strength.

SUMMARY OF THE INVENTION

The task to be solved through this invention consists in the creation of a simple and efficient method of well sanding prevention using gravel pack, including gravel pack placement in the well, where a new type of bulk material with a crushing strength and chemical inertness is used as the gravel pack for underground formations treatment.

The technical result to be attained in the implementation of the technical solution claimed consists in the assurance of a better filtration of sand and fines through a more uniform distribution of the gravel pack as polyDCPD, its high thermal stability and high crushing strength. Due to the fact that the specific density of the particles is close to 1, precipitation of the gravel pack particles during the gravel pack precoating is eliminated which is especially important for horizontal boreholes. Besides, due to the lower filler density less viscous carrier fluids may be applied which ensures reduced friction during the injection.

The technical result delivered is attained due to the fact that the gravel-pack well sanding prevention method including the gravel pack placement in the well uses bulk material represented by polydicyclopentadiene (hereinafter referred to as polyDCPD) particles. Hereby the polyDCPD particles may have various shapes, e.g., spherical, elongated, polygonal, cubical, they may be made as fibers. The polyDCPD filler may be additionally strengthened using filler, like clay or silicon dioxide, or ceramics, of fibers.

DETAILED DESCRIPTION

This invention is related to the gravel-pack well sanding prevention method including the gravel pack placement in the well using polyDCPD materials as the gravel pack. The polyDCPD gravel pack particles may have any dimensions and shape in any combinations. PolyDCPD material has crushing strength up to 60 MPa and density of about 0.95 . . . 1.03 g/cm³. Therefore polyDCPD particles may be in suspended state and carried by the fracture fluid. The advantage is better sand and fines filtration resulting from the denser and more uniform polyDCPD particles' distribution, its higher thermal stability and crushing strength. Due to the fact that the specific density of the particles is close to 1, precipitation of the gravel pack particles during the gravel pack precoating is eliminated which is especially important for horizontal boreholes. Besides, due to the lower filler density less viscous carrier fluids may be applied which ensures reduced friction during the injection.

Of all polymers polyDCPD has a unique combination of mechanical, chemical and physical properties which makes it a good alternative to polyethylene, polystyrene, fiber glass, polyether, graphite fiber, aluminum alloys and other materials. PolyDCPD has low density (close to that of water), an excellent combination of rigidity and impact strength; stable dimensions, excellent chemical stability in acids, bases, crude oil, excellent thermal stability; its mechanical processing is easy.

High-purity polyDCPD Noveon is manufactured by “Telene®DCPD” Company for European and Chinese markets.

PolyDCPD “Metton® PDCPD”, which is basically similar to “Telene®” is manufactured by Metton America Inc. which is going to startup its mass production as an alternative to fiber glass, wood and metal.

Gravel pack particles represented by polyDCPD proppants may have various dimensions, shape and their combinations. Non-spherical proppants may be elongated, protruded, polygonal, cubical, fiber etc. particles. PolyDCPD proppants may be reinforced with suitable fillers, like clay, silicon dioxide, fibers, ceramics etc.