SU829876A1 - Method of stepwise cementing of wells - Google Patents

Description

(54) METHOD OF STEPPED CEMENTING WELLS

The invention relates to the drilling of wells, in particular, to methods for their step cementing. . There is a method of step cementing of wells, including injection of the first stage cement slurry from the casing shoe to the annular packer installed above the reservoir with a low fracture gradient modulus, absorbing the cement slurry, the annular space and the second stage cement slurry above the packer above the packer, above the packer, and the second stage cementing above the packer and the second stage above the packer to the hub of the cement slurry; This method is the need to drill the internal flow channel of the packer, which leads to additional time and money spent on the process of mounting wells in general. The closest to the present invention is a method of step cementing wells with absorbing layers that are sloped to hydraulic fracturing, cementing nepBoi f steps by pumping cement into the casing and then sending it to the packer installation interval on the casing, sealing the casing using a packer, cementing the second stage by pumping cement into the annular space of the column, displacing the drilling fluid from the well, and waiting for the cement to harden 2. . However, this method has disadvantages inherent in the reverse cementing method used for the second stage. As a result, it is possible either to prematurely end cementing, or to leave the cement glass in a large casing (due to premature clogging of the circulation channels of the filter with filler in the first batch of cement mortar, or because of the low effectiveness of the blocking capacity of the selected filler). In addition, a reduction in the quality of the second stage cementing is not excluded due to the possible dilution of the cement slurry with drilling mud.

The purpose of the invention is to reduce the time spent on cementing wells drilled in rocks containing fracture prone layers.

This goal is achieved by installing a packer over an absorbing reservoir, the hydraulic fracturing module of which is smaller than that of the overlying reservoirs, and pumping cement mortar into the annular space of the column with the drilling fluid displaced from the well into the absorbing reservoir to. establish the equilibrium state of the well-reservoir, then cement hardening is expected, after which the cement slurry is pumped into the annulus to the depth of the column. The method of staged cementing wells is described as follows.

An operating column below the intermediate column shoe below the formation, the hydraulic fracturing module of which is smaller than that of the underlying strata, is fitted with a collar packer. The first stage is cemented in the usual way (by measuring the cement mortar in the column) with the raising of the tampon solution from the shoe to the installation interval of the pack. Thereafter, without rupture in time, the annular space is packed in the packer installation interval and the cement slurry is pumped into the annular space between the production and intermediate columns from the wellhead. When creating a pressure exceeding the pressure of the hydraulic fracturing located between the packer and the intermediate column, the drilling fluid and a portion of the tampons are crushed into this formation until the equilibrium state is established. ki well-reservoir. After the cement has hardened, the cement slurry is pumped into the annular space without drilling mud by a mimotek to the wellhead.

In this way, the necessary cementing of production casing strings to the wellhead in gas fields and oil deposits is provided.

as well as high gas factor oil fields.

For example, the following well construction is adopted: a conductor with a diameter of 324 mm descends to a depth of 400-420 m; an intermediate column with a diameter of 245 mm is lowered to a depth of 970-980 Mjf; the production column with a diameter of 168 mm is lowered to a depth of 2450-2550 m. All columns are cemented to the full depth of their descent. According to geological and technical conditions, when wells are mounted with production columns, it is necessary to lift the cement slurry to the wellhead. At the same time, the presence of absorbing layers, for example, the slip of the intermediate column does not allow to lift the cement slurry more than 100-150 m in bashmak intermediate column.

To carry out the method of cementing, the production string below the intermediate column shoe, for example, 20-25 m, under the formation with a modulus of the formation pressure gradient equal to, for example, 0.1600, 165 kgf / cm. isolating formations whose internal passageway is equal to the diameter of the production casing. Next, the first stage is cemented by a direct method according to the conventional technology with the cementing slurry prior to the packer installation interval. Thereafter, without a gap in time, the annular space is packed and the operation is carried out in accordance with the foregoing.

The positive effect of the use of the invention is due to the reduction of time and money spent on drilling devices for step cementing of wells or bridges between steps of cementing.

Claims (2)

1. Temporary packer application guide for two-stage cementing. M., VNIIBT% 1974. 2. An overhead packer fitting for two-stage combined cementing of columns. Prospect VDNH, VSHOENG, 1972, No. 4773, Zac. 540.