RU2370637C1 - Method of recovery of yield and bringing to operation of temporarily shut-in wells with complicated structure of collectors under conditions of abnormally low bed pressure - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: method of recovery of yield and bringing to operation of temporarily shut-in wells with complicated structure of collectors under conditions of abnormally low bed pressure including repair, insulating, and exposure of producing bed consists in following: initially, sand plug is washed for depth 2-3 m below current gas-water contact (GWC); producing string is callipered, shank end out of casing tubes of smaller diametre is lowered into producing string up to head of washed sand plug; head of shank end is arranged 20 m above top of producing bed. The shank end is cemented with cement grout; upon waiting-on-cement completion (WCC) two columns, the producing column and the shank end are perforated in interval below the first over current GWC clay interlayer to depth 2-3 m below current GWC. Water insulating composition at volume 15-20 m³ is pumped through perforated openings made for water insulation; composition is forced through into depth of the producing bed creating a water insulating screen with cement grout of volume 3-5 m³; a cement sleeve 1-2 m above the first over the current GWC clay interlayer is left at the bottomhole. Upon WCC perforating is performed for operation of two columns, the producing column and the shank end in interval above the second over the current GWC clay interlayer up to the top of the producing bed; gas discharge is initiated. Composition containing Portland cement, super-plasticiser C-3, polyvinyl alcohol and polypropylene fibre is used as cement grout; while for perforation either a high-power cumulative perforator or hydraulic jet are used.

EFFECT: insulating fluid entry, ensuring pressure tightness of producing column and additional gas withdrawal from earlier shut-in wells.

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Description

The invention relates to the oil and gas industry, namely, to restore the productivity of idle oil and gas wells with complex reservoirs under conditions of abnormally low reservoir pressure (ANP).

In the fields of Western Siberia there are a large number of oil and gas deposits with complex reservoirs, in which interlayers of various permeability alternate, including sandstones and clay. Moreover, the thickness of such deposits is often small, which forces the secondary opening of the reservoir, perforation of the production string with a continuous interval and double density.

At the final stage of developing such deposits, a large number of wells are decommissioned due to a decrease in reservoir pressure, water cut associated with a rise in gas-water contact (GWC), low productivity, collapse of the production string due to the occurrence of a large difference in rock and bottomhole pressure, i.e. rock pressure and pressure in the well and reservoir. Under these conditions, it is difficult to restore productivity and remove the well from inaction by traditional methods. It is technically impossible to eliminate the leakage of the production casing by installing insulating packers or longitudinally corrugated plasters due to its continuous perforation and reduced strength of the production casing.

A known method of restoring productivity and putting into operation idle oil and gas wells, including the production of repair and insulation works and opening the reservoir [RF Patent, No. 2273718 Е21В 29/10, filed 02.07.04, publ. 04/10/06].

The disadvantage of this method when restoring the productivity of idle wells with difficult-to-build reservoirs under the conditions of oil production is that the crimping of longitudinally corrugated plasters can lead to even greater destruction of the leaky, repaired, production casing interval, which will contribute to a significant excess of rock pressure over bottom hole pressure and continuous double density perforation production casing. In addition, the method does not eliminate the flow of formation water to the bottom and does not restore the productivity of the well itself, on the contrary, it contributes to further contamination of the bottom-hole formation zone (PZP).

A known method of restoring productivity and putting into operation idle wells, including the production of repair and insulation work and opening the reservoir [Pat. RF, No. 2231630 Е21В 43/00; 43/32, claimed 2002, publ. 2004].

The disadvantage of this method when restoring the productivity of idle wells with difficult to build reservoirs under the conditions of oil production is that when perforating the production string with high power perforators, there is a high probability of a leak in the cement ring behind the string, its complete or partial destruction, which will contribute to an even greater influx of formation water to the bottom of the well. In addition, this method does not eliminate the leakage of the production string with a large difference between the mountain and bottomhole pressures.

The challenge facing the creation of the invention is to develop a reliable method for restoring productivity and putting into operation idle wells with complex reservoirs under the conditions of oil production.

The achieved technical result, which is obtained as a result of the creation of the invention, consists in isolating the inflow of formation water, ensuring the tightness of the production string and in obtaining additional gas production from previously idle wells.

The task and technical result are achieved by the fact that in the method of restoring productivity and putting into operation idle wells with complex reservoirs under the conditions of oil production, including the repair and insulation works and opening the reservoir, the sand plug is initially washed to a depth of 2-3 m below current gas-water contact - GVK, template the production string, lower the liner from casing pipes of a smaller diameter into the head of the washed sand plug with placement tin of the liner 20 m above the top of the reservoir, cement the liner with cement mortar and after the waiting period for cement hardening the OZC perforate two columns, production casing and liner, in the interval below the first over current GVC clay layer to a depth of 2-3 m below current GVK, through the perforation holes formed for waterproofing, pump the water-insulating composition in the volume of 15-20 m ³ , push it through 2-3 m below the current GVK, through formed under water perforation holes pump a water-proofing composition in the volume of 15-20 m ³ , push it deep into the reservoir with the formation of a water-proof screen with cement mortar in the volume of 3-5 m ³ , leaving a cement glass 1-2 m higher on the bottom than the first clay above the current GWC interlayers, and after the OZC perforation is carried out for the operation of two columns, production casing and liner, in the interval above the second over the current GWC clay interlayer to the roof of the reservoir and the gas inflow is caused, When this as cement mortar is used the composition comprising Portland cement, superplasticizer C-3, polyvinyl alcohol and polypropylene fiber, and used as a powerful cumulative perforator punch or perforation performed hydrosandblast.

In Fig.1 shows the design of the well with complex reservoirs under the conditions of the API, in Fig.2 shows a diagram of the implementation of the proposed method when washing the sand plug and lowering the liner, Fig.3 is the same in the process of perforation "under the waterproofing" and isolation of the influx formation water, figure 4 - the same, in the process of perforation "for operation" and the call of gas flow from the reservoir.

The method is implemented in a well idle for a long time (Fig. 1), in which the production casing 1 is perforated throughout the entire thickness of the reservoir 2 evenly, with a continuous interval and double perforation density, the wellbore is partially blocked by a sand plug 3, GVK 4 2-3 m lower current GVK 4, template production casing 1 and lower liner 5 from casing of smaller diameter to head 6 of washed sand plug 3 with head 7 of liner 5 20 m above the roof 8 of productive formation 2 to prevent possible collapse of the production casing 1 due to the large difference between the mountain and bottomhole pressure in the conditions of the API. The shank 5 is cemented with cement mortar 9, leaving a cement cup 10 1-2 m high in the shoe 11 of the shank 5. Moreover, to prevent the cement mortar 9 from absorbing under the conditions of ANPD and to obtain a strong cement stone, a composition containing, for example, wt.%: Superplasticizer C -3 0.5-1, polyvinyl alcohol 0.5-1, polypropylene fiber 0.06-0.08, Portland cement the rest. Portland cement PTC 1-50 or PTC 1-100 can be used as portland cement, and a polypropylene fiber called “fiber” or an inert fibrous filler can be used as polypropylene fiber.

After completion of the waiting period for cement hardening (OZC), two columns are perforated (Fig. 3), production casing 1 and liner 5, in the interval below the first above the current GWC 4 or head 6 of the washed sand plug 3 of clay interlayer 12 to a depth of 2-3 m below the current GVK 4, that is, the lower part of the reservoir 2. Perforation is carried out by a powerful cumulative perforator or conduct sandblasting perforation (GPP). As a cumulative punch, you can use the PJ 2906 omega or PKS 80, PRK 42C punch. The waterproofing composition 13 is pumped in a volume of 15-20 m ³ through the perforations 14 formed “for waterproofing”. As the waterproofing composition, “water glass”, PVA 18/11 or PVA V1N can be used. The waterproofing composition 13 is pressed deep into the productive formation 2 with the formation of the waterproofing screen 15 with cement mortar 16 in a volume of 3-5 m ³ , leaving a cement cup 17 1-2 meters higher at the bottom of the first clay layer 12. The composition of cement mortar 16 is similar to the composition of cement mortar 9 when cementing the shank 5.

After OZZ (figure 4) carry out perforation "for operation" of two columns, production casing 1 and liner 5, in the interval above the second over the current GWC 4 clay layer 18 to the roof 8 of the productive formation 2, that is, the upper part of the productive formation 2. back pressure on the productive formation 2 call the flow of gas through the perforations "for operation" 19. After completion of the well and gas-dynamic studies, the well is put into operation.

An example implementation of the method in well No. 307 of the Vyngapurovsky field

Initially, a sand cork was washed in the well 2 m below the current GWC, a production string with a diameter of 168 mm was mapped and a liner of 114 mm casing was lowered to the head of the washed sand cork. At the same time, the head of the liner turned out to be 20 m above the top of the reservoir, which ensures the prevention of crushing of the production string due to the large difference between the mountain and bottomhole pressure in the conditions of the API. The shank was cemented with cement, leaving a 2 m high cement cup in the shank shoe. Moreover, to prevent the absorption of cement mortar under the conditions of ANPD and to obtain a durable cement stone, a composition was used containing, wt.%: Superplasticizer C-3 0.7, polyvinyl alcohol PVA 18/11 0.7, polypropylene fiber - "fiber" 0.07 Portland cement PTC 1-50 98.53.

After the OZC, two columns, a production string and a liner, were perforated in the interval below the first clay layer over the current GWC to a depth of 2 m below the current GWC. Perforation was carried out by a powerful cumulative perforator - PJ 2906 "omega", which ensures the creation of long cracks without destroying the cement stone behind the production casing. Such a perforator belongs to the “gentle” perforators that do not destroy the integrity of the cement stone. After that, the waterproofing composition - “liquid glass” was pumped in accordance with GOST 13078-81, in a volume of 15 m through the perforation holes formed “for waterproofing”. The waterproofing composition was pressed deep into the reservoir with cement mortar consisting of PTZ 1-50 Portland cement, S-3 superplasticizer, PVA 18/11 polyvinyl alcohol and “fiber” polypropylene fiber, in a volume of 4 m ³ , leaving a cement cup 1 in the bottom of the face m above the first clay layer. The water-insulating composition, pumped deep into the reservoir, formed a water-insulating screen, which prevents the formation water from moving towards the bottom of the well. Polypropylene fiber - “fiber”, made of polypropylene C ₃ H ₆ , is a monofilament substance, the surface of which is coated with a composition that promotes dispersion and adhesion to cement mortar, fiber length 6 mm, fiber diameter 18 microns.

After the OZC, two columns, a production string and a liner, were perforated “for operation” in the interval above the second clay layer over the current GWC to the top of the reservoir. By reducing the back pressure on the reservoir, the gas flow through the perforations “for operation” was called. After testing the well and conducting gas-dynamic studies, the well was put into operation.

The proposed method for the restoration of productivity and commissioning of idle wells with complex reservoirs under the conditions of oil production is more reliable than its counterparts. It eliminates the flow of produced water into the well, helps to reduce sand removal from the reservoir, prevents further destruction of the production string, increases the likelihood of restoration of well productivity and provides additional gas production from a previously idle well.

Claims (1)

A method of restoring productivity and commissioning idle wells with complex reservoirs under conditions of abnormally low reservoir pressures, including repair and insulation work and opening a reservoir, characterized in that the sand plug is initially washed to a depth of 2-3 m below the current gas-water contact - GVK, template the production casing, lower the liner from the casing of a smaller diameter into the head of the washed sand plug with the placement of the head of the tails 20 m above the top of the reservoir, cement the shank with cement mortar and, after the waiting period for cement hardening, OZZ perforates two columns, production casing and liner, in the interval below the first over the current GWC clay layer to a depth of 2-3 m below the current GVK, through the perforation holes formed for waterproofing, pump the waterproofing composition in a volume of 15-20 m ³ , push it deep into the reservoir with the formation of a waterproofing screen and with a cement mortar in a volume of 3-5 m ³ , leaving a cement cup 1-2 meters higher on the bottom than the first clay clay layer above the current GWC, and after the OZC, two columns, a production casing and a liner are perforated for operation, in the interval above the second over the current GWC clay interlayer to the top of the reservoir and gas inflow, while using a composition containing Portland cement, S-3 superplasticizer, polyvinyl alcohol and polypropylene fiber as a cement mortar, and as a perf the speaker uses a powerful cumulative perforator or carry out sandblasting perforation.

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