RU2081299C1 - Method for cementation of oil and gas wells - Google Patents

Abstract

FIELD: oil and gas industry. SUBSTANCE: according to method, before injecting concrete mix according to reverse circulation procedure water or air is pumped into casing string. Pumping is effected under pressure. Subsequently water or air is released for disposal. Disposal is effected at speed ensuring equality of volumetric flow rate of water or air being disposed from casing string and of concrete mix being injected into it. Process is checked by pressure-vacuum gauge. Counterpressure of concrete mix is maintained at well head. This is realized by regulation of water or air disposal. Termination of concreting is checked by float. Float is lowered into casing string by copper wire of deep-type winch. EFFECT: enhanced efficiency.

Description

 The invention relates to the field of concreting oil and gas wells.

 The method is proposed instead of cementing oil and gas wells and is based on reverse circulation (1). Fine-grained concrete mortar as a grouting solution is pumped into the well. Aggregate sand, particle size not more than 5 mm.

 The proposed method of concreting wells is characterized in that before the injection of concrete into the annular space, water or air is calculated to be injected into the casing. The discharge of water (air) from the column causes the reverse circulation.

 Simultaneously with the discharge of water (air) concrete solution is pumped into the annulus.

 The discharge is carried out at a speed that ensures the equality of the volumetric flow rates of the discharged water (air) and the injected concrete.

 This equality is controlled by a manometer-vacuum gauge in the annular space, supporting the backpressure of the concrete mixture at the mouth in the range of 0.01-0.02 MPa by adjusting the discharge of water (air).

 Monitoring the end of concreting is carried out by a float, which is lowered into the casing on the measuring wire rope of a deep winch. The volume and weight of the float are selected so that in the drilling fluid the float sinks and stops in the concrete solution.

 As the annular space is filled with concrete, the pressure drop increases, providing reverse circulation.

 If necessary, a squeezing liquid is pumped after the concrete mixture.

 The technical result.

1. Replacement of cement cement with sand (other aggregate), including sand from local quarries in an amount of over 60%
2. The concrete mixture is pumped into the well in a non-pressure mode, which allows for a large downward speed of the concrete mixture and high quality concreting. This mode allows us to use USP-50 sand mixing plants both for continuous preparation of concrete mix and for its injection into the well. USP-50 is supplied with cement mortar prepared by standard technology with cementing aggregates and mixers.

 Two USP-50 units are installed closer to the wellhead and from each lay their own line to the well.

 Having spent their supply of sand, these USP-50 receive and pump concrete mixture from other USP-50 into the well.

 3. The duration of the operation is reduced by eliminating the operation of pumping squeezing fluid into the casing.

 4. Practically removed restrictions on the height of concreting.

 To lower the float on the measuring wire, the head cover of the cementing column is equipped with an oil seal under the measuring wire.

 The float is suspended from the load on the brake lever and lowered to a sufficient depth so that the weight of the measuring wire exceeds the force pushing the wire against pressure on the gland. The brake lever prevents the float from rising relative to the load, i.e. the upward flow in the pipes will not toss the float and will not entangle the measuring wire.

 The composition of the concrete mix is specified according to the results of laboratory analysis and its trial pumping of the USP-50 sand mixing plant.

 It is also necessary to practically clarify at what speed the descent of the float in the drilling fluid will trigger the brake lever. Accordingly, reduce the circulation rate at the end of the operation. It is important to note that when concreting to the mouth, materials taken with a margin remain in the bunkers and can be used in the future, and the sand does not have a shelf life.

 Water is discharged through an adjustable nozzle, the manufacture and calculation of which is not difficult. Regulation is carried out constantly, because as the well is filled with concrete, the pressure on the head of the cementing column is constantly increasing.

Claims (1)

 A method of concreting oil and gas wells for reverse circulation instead of cementing them, including monitoring the completion of concreting, characterized in that cement slurry is used as a grout, before which water or air is injected into the casing under pressure, followed by their discharge at a speed of ensuring equal volumetric flow rates of discharged water or air from the casing and the injected concrete, which are controlled by a manometer-vacuum gauge, at the same time, backpressure of the concrete mixture is maintained at the mouth by adjusting the discharge of water or air, and the end of concreting is controlled by a float, which is lowered into the casing on the measured wire rope of the deep winch.