Isolation method of productive formation from bottom water inflow

FIELD: oil and gas industry.

SUBSTANCE: isolation method of productive formation from bottom water inflow involves well drilling with opening of productive formation and arrangement of the working face below the level of oil-water contact (OWC), installation of casing pipes above OWC level with further cementing, cleaning of the well below casing pipes, pumping of waterproofing sealant to the cleaned well zone with isolation of bottom water and perforation of casing pipes. Well is drilled in two stages, the first one of which is performed with the main shaft to the roof of productive formation, and the second one - with pilot shaft of smaller diameter. Formation properties are investigated, and the main shaft is deepened to the level located above OWC level before casing pipes are installed. Shaft cleaning below casing pipes is performed after cementing by drilling the pilot shaft with the bit of larger diameter below OWC, and OWC zone is perforated.

EFFECT: method provides the creation of a reliable screen in OWC zone owing to avoiding the operation used for creation of sand-clay plug and cleaning of the well shaft in OWC zone after it is drilled and reinforced with casing pipes, creation of reliable waterproofing screen due to OWC zone perforation, reduction of costs for waterproofing sealant, which is due to the fact that it is pumped directly to OWC zone after perforation.

4 dwg

 

The invention relates to the oil and gas industry and can be used for isolation of the productive formation from the inflow of bottom water during the construction of wells.

There is a method of zonal isolation in a well (patent RU No. 2183265, C2 7 EV 43/32, 33/13, publ. bull. No. 16 from 10.06.2002, including the descent into the well casing pipe, equipped with a device isolation layer, to isolate the annulus of the well corresponding to the aquifer portion of the reservoir, from the annulus to the rest of the well and cementing the annulus above and below the aquifer portion of the reservoir, and then cement the annulus corresponding to the aquifer portion of the reservoir, by filing a cement slurry through the channels of the specified device.

The disadvantages of this method are:

- ability to upload plugging composition only through the channels in the device isolation layers, which can lead to partial blockage of vodoprivreda of the reservoir;

- the need to use additional devices, which leads to lower reliability of the method and increase material costs.

The closest technical solution is a way to isolate the productive formation from the flow under the public water in the drilling process (see Gabdullin RG, Starov H., Zvegintsev VI ON the prevention of the irrigation wells with bottom water". In kN. Researchers - production, iss.5. Almetyevsk, 1969, p.37-43), which includes the drilling of wells with partial or complete opening of the water-saturated part of the reservoir and the initial determination of the level of oil-water contact (OWC), a sandy-clay tube and mount wells production column to tube, leaching sandy-clayey tube, determining the integrity of the cement sheath behind the production column and the injection water composition over the entire open hole capacity of the reservoir and the opening of the oil-saturated part of the reservoir water perforation.

The disadvantages of this method are:

the necessity of establishing a sandy-clay tube, which leads to additional costs;

- possibility of vymyv sandy-clayey tube during cementing of the production casing;

- the complexity of the injection water composition, related to the fact that during the drilling of the borehole walls is formed clay crust, which prevents the penetration of substances into the reservoir;

- clogging part of the pore space when creating a sandy-clay tubes and leaching;

- the high cost of water composition, because pumping is produced by all power and water-saturated part of the formation.

The technical task of the present invention is to provide a reliable screen in the area KSS due to the exclusion of the operation of sand-clay tubes and cleaning of the wellbore in the zone KSS after drilling and fastening the casing, creating a reliable water screen due to the perforation zone KSS, as well as reducing the cost of water structure associated with the fact that its injection is made directly into the zone KSS after perforation.

The solution of this problem is achieved by the method of isolation of the productive formation from the inflow of bottom water, which includes the drilling of wells with the opening of the productive formation and the placement of the face below the level of the KSS, the installation of the casing above the level of KSS with further cementing, cleaning of the borehole below the casing, the injection water composition in the treated area well insulated with bottom water and the perforation of the casing string.

What's new is that drilling is produced in two stages, the first of which produce the main trunk to the roof of the reservoir, and the second pilot hole of smaller diameter, after investigation of the properties of the reservoir and prior to installation of casing pipes produce a deepening of the main shaft to a level located above the level of KSS, after cementing a wellbore cleanout lower casing carried the Yat-drilling pilot barrel bit larger diameter below the level of KSS with subsequent perforation zone KSS.

Figure 1 shows two phases of drilling.

Figure 2 shows the deepening of the above KSS main hole and fastening its casing.

Figure 3 shows the cleaning of the wellbore below the casing by drilling pilot barrel bit larger diameter and perforation zone KSS.

Figure 4 shows the creation of waterproofing screen and the opening of the oil-saturated part of the formation.

The method is as follows.

At the first stage of drilling the main shaft 1 (Fig 1) produce to the roof 2 of the productive layer 3. Then open the reservoir 3 below soles 4 slurry portion 5 of the reservoir 3 pilot hole 6 of a smaller diameter. Conduct geophysical studies specify the location of the zone KSS 7 and soles 4 slurry portion 5 of the reservoir 3. Deepen the main shaft 1 to level 8 (figure 2) above the zone KSS 7 on mud and produce descent casing 9 in the fixed barrel 1 and cementing. Then move on to technical water and razvarivat pilot shaft 6 of the lower casing 9 bit larger diameter 2-3 m below KSS 7. When drilling the wellbore 10 (figure 3) cleaned of cement remaining after cementing of casing pipes 9 and through the opening on the water eliminates the clogging zone KSS 7 mud, which, in turn, p is adequate to restore pickup zone KSS 7. Then for reliable penetration of water composition 11 (figure 4) produce a perforation 12 (3, 4) of the barrel 10 wells by any known method in the area of the cap 7. In the well produce the descent of the tubing with the packer (Fig. not shown) and through the string of pipe produced injection water composition 11 (figure 4) in the perforations 12. As a waterproofing composition 11 can be used, for example, hydrophobic emulsion (oil - 30-49%, produced water - 50-68%, emulsifier-wetting agent - 1-2 vol.%). After that, the well pumped cement slurry 13 to secure water composition 11. Well I leave for structural hardening water composition 11 and hardening of cement 13. Next make the opening 14 (e.g., abrasive jet perforation) saturated with part 15 of the reservoir 3 and the well completion.

The proposed method provides reliable screen in the area of KSS due to the exclusion of the operation of sand-clay tubes and cleaning of the wellbore in the zone KSS after drilling and fastening the casing, creating a reliable water screen due to the perforation zone KSS, as well as reducing the cost of water structure associated with the fact that its injection is made directly into the zone KSS after perforation.

The method of isolation of the productive formation from p is itoka bottom water, including the drilling of wells with the opening of the productive formation and the placement of the face below the level of the oil-water contact (OWC), installation of casing above the level of KSS with further cementing, cleaning of the borehole below the casing, the injection water composition in the treated area well insulated with bottom water and the perforation of the casing string, wherein the drilling produced in two stages, the first of which produce the main trunk to the roof of the reservoir, and the second pilot hole of smaller diameter, after investigation of the properties of the reservoir and before installing:casing pipes produce a deepening of the main shaft to a level located above the level of KSS, after cementing a wellbore cleanout lower casing is produced by drilling a pilot stem a bit larger diameter below the level of KSS with subsequent perforation zone KSS.



 

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