Well screen

FIELD: oil production industry, particularly devices preventing ingress of formation sand and propane with extractable formation fluid from bottomhole formation zone into well.

SUBSTANCE: well screen comprises perforated tube and filtering member with pore dimensions increasing in radial direction from outer screen surface to inner one. Filtering member is installed coaxially to perforated tube surface and made of foamed metal having three-dimensional cellular structure. Cellular structure includes many-sided cells with permeable faces so that solid sand filter of deposited particles may be formed inside foamed metal. Deposited particles are mechanically attached to randomly oriented ribs and faces of the cellular structure.

EFFECT: increased filtering performance.

2 dwg

The invention relates to the oil industry and can be used in devices that prevent the flow of formation sand and proppant from the bottom zone in the well with the produced reservoir fluid.

Known downhole filter comprising a perforated pipe and metal-ceramic filter element of sintered powder, mounted coaxially with the outer side of the perforated pipe and with a gap relative to the last (ed. the certificate of USSR No. 1161692, E 21 In 43/08, 1985).

A significant disadvantage of this filter is its poor hydraulic performance, low porosity and correspondingly low pore volume, causing low purification. In addition, a filtering element with the same pore size in the thickness leads to a rapid clogging of its surface layer with a mixture of small and large particles of sand and the resource constraint of continuous operation. Such a filter is virtually impossible regeneration, which significantly increases the cost of its operation.

Closest to the claimed technical essence and the achieved result is well filter containing a perforated pipe and a filter element made with decreasing pore size in the radial direction from the outer surface to the interior is Anna and mounted coaxially with the outer surface of the perforated pipe (US No. 3768557, E 21 b 43/08, 1973).

This filter is characterized by the complexity of manufacturing. For the formation of the filter layers with different pore size requires additional training: pre-concentric install partition walls, the space between the walls is filled with particles from a strictly specified size, then the partitions are removed. The disadvantage of this design is low holding capacity of the filter material due to the limited volume of interconnected pores ˜35-40%, which reduces the service life of the filter.

The proposed design is more adaptable to production and can improve throughput while reducing hydraulic resistance, to increase the holding capacity, the resource of continuous operation and utilization of the volume of the filter, as well as to improve its Regenerist.

This technical result is achieved by the fact that in the downhole filter containing a perforated pipe and a filter element with a pore size decreasing in the radial direction from the outer surface to the inner mounted coaxially with the outer surface of the perforated pipe, according to the invention, the filter element is made of nanostructural catalyst with spatial mesh frame composed of polyhedral cells with permeable gr is, gives and with education inside of nanostructural catalyst natural continuous sand filter of the deposited particles is mechanically coupled with stochastically oriented in space faces and edges of the honeycomb frame.

The use of nanostructural catalyst with a spatial frame, consisting of polyhedral cells with permeable faces and pores inside, enables more effective cleaning of the reservoir fluid.

Preferably the use of a filter element with a pore diameter decreasing in the direction of filtration from 1.0 to 2.5 mm up to 200-300 μm, the change may be discrete or gradual. The porosity or volume of interconnected pores in the local volume of the filter element is 84-96% regardless of the diameter of the pores, which is a structural feature of the nanostructural catalyst.

Install the filter element made with decreasing pore size in the proposed design does not require additional preparation and is done in one stage.

1 schematically shows a filter element of nanostructural catalyst with decreasing pore size in the radial direction from the outer surface to the inner section. Figure 2 shows the spatial mesh structure phenomenalism filter.

The filter (figure 1) consists of a perforated pipe 1 with what tertiary 2 and the filter element 3 of nanostructural catalyst with decreasing pore size in the radial direction from the outer surface to the inner.

The filter works in the following way. After installing the filter in the well and its commissioning mixture reservoir fluid with a mechanical particles of impurities is supplied to the filter element from the nanostructural catalyst 3. From this mixture on the outer contour and the surface layer phenomenalism filter element 3 are deposited the largest particles, forming a stable arch structure. The sustainability of such arched structures of the proppant or sand is covered by a mechanical clutch with stochastically oriented in space faces and edges of the honeycomb skeleton of the filter.

Cleared most of the large particles flow of liquid remaining in it, mechanical impurities continues to move through the wire mesh frame. The stream is divided into separate streams, the speed of which is lower than the input flow rate. As damping fluid velocity inside the fine particles also lose speed and delayed cellular frame of the filter element 3. The intensity of the process of separating particles from a fluid is determined by the balance between the weight of the particles depending on their size, and the lifting force of the stream is directly related to the pore size of the honeycomb frame, through which it flows. As a consequence, the size of the detainees frequent the C is reduced by the thickness of the filter element 3 from the outer surface to the inner. Delayed particles form inside phenomenalism filter element natural continuous sand filter, the pore size of which is reduced in the radial direction in accordance with variations in the diameter of pores phenomenalism element. When the movement of the reservoir fluid through the formed composite filter element consisting of nanostructural catalyst and a natural sand filter, increases the likelihood of deposition of fine particles, which results in high neness.

Purified from the main quantity of mechanical impurities, the reservoir fluid with a small part of the smallest particles of sand passes through the 2 holes of the perforated pipe 1, it rises and falls in the tubing (not shown), and on it - on the surface.

The presence of communicating porosity in combination with a variable redistribution filter provides good regenerative ability, thus the regeneration of the filter can be performed directly in the borehole by backwashing with clean oil.

It is possible to vary within wide limits the diameter of pores in the thickness of the filter can catch in the last volume mechanical particles, the size of which varies from a few tens to hundreds to thousands of microns. In particular, eff the active application phenomenalism filter to collect the proppant after conducting hydraulic fracturing.

The high porosity of nanostructural catalyst is made of a filter element, reduces the overall weight of the downhole filter and transmitted from him axial load on the tubing that leads to efficiency podnebesnoi install the filter without a packer. The use of lightweight phenomenalistic filters facilitates the operation of multilayer deposits, which provides for the placement of multiple filters in front of each productive layer.

Thus, selected for downhole filter structure allows the material during operation to create a combined filter element, which combines the advantages of nanostructural catalyst having a high dirt capacity, and the sand filter formed inside the pores of nanostructural catalyst and providing additional continuous cleaning fluid during its movement, which, ultimately, makes it possible to achieve high degree of purification.

The downhole filter containing a perforated pipe and a filter element made with decreasing pore size in the radial direction from the outer surface to the inner and mounted coaxially with the outer surface of the perforated pipe, characterized in that the filter element is made of nanostructural catalyst with spatial mesh frame consisting of mn is ohrannyh cells with permeable faces, and with education inside of nanostructural catalyst natural continuous sand filter of the precipitated particles is mechanically coupled with stochastically oriented in space faces and edges of the honeycomb frame.