SU1418471A1 - Casing cementing apparatus - Google Patents

Description

(21) 4096055 / 22-03

(22) 07/14/86

(46) 08/23/88. Bul No. 31

(71) Krasnoyarsk department of drilling and testing wells of the East-Siberian Research Institute of Geology, Geophysics and Mineral Resources

(72) V.A.Prasolov, I.A.Istomin and V.F.Shchipachev

(53) 622.245.42 (088.8)

(56) USSR Copyright Certificate No. 1044769, cl. E 21 B 33/16, 1982.

USSR author's certificate number 625023 ,.kl. E 21 V 33/14, 1976.

(54) DEVICE FOR CEMENTING CLOSED. COLUMN

(57) The invention relates to mountainous

prom-sti and allows you to increase the reliability of the device. It includes a housing (K) with an axial channel 2 and peripheral holes 3 in which filtering elements 4 are installed in the form of a hollow cylinder (PC), diaphragms 5. Above them pins 6 are movably mounted, and a check valve 7 is placed in channel 2. To 1 is installed. supporting disk 8 with axial holes 9. The PC is located between K 1 and disk 8. The upper end of the PC is rigidly connected to K I, and the lower end is connected to disk 8. Sealing plug, fitting onto pins 6, destroys the diaphragms 5. Valve 7 closes. The cement slurry is partially dehydrated on element 4, and the filtrate of the solution flows in

(L

00

four;

The ftocTb of the column below K 1. In the cavity of the inter-HU K 1 and disk 8, a cement-compaction is formed, the compression of which causes an additional compaction of the defective mass. As far as compaction

Resistance to compression of cement mass increases proportionally. arr., piercing the squeeze fluid, the shoe part of the column is completely turned on. 1 il.

one

The invention relates to the mining industry, namely to the oil and gas industry, and can be used in casing cementing.

The purpose of the invention is to step up the operation of the device in operation by increasing its tightness after cementing the casing under the conditions of an overpressure in the forward direction.

The drawing shows the device, General view, longitudinal section.

The device includes a housing 1 with an axial channel 2 formed therein and peripheral apertures 3, filtering elements 4 and diaphragms 5, pins 6j installed in the peripheral holes 3j, pins 6j installed above the diaphragms 5j, placed in the axial channel 2 of housing 1 , supporting disk 8 with axial holes 9 made in it, thrust disk 10 through which pin 6 is passed.

The device operates as follows ...

After injection of the required amount of cement slurry into the well, a sales plug is injected into the well, which, sitting down on rim 6, destroys diaphragms 5. When the pumps stop supplying, the check valve 7 is closed.

Under the action of pressure drop, as the difference in pressure of the pillars of the cement slurry in the annulus and lighter squeeze fluid in the column, the cement slurry is partially dehydrated on the filter element 4. In the cavity between the housing 1 and the limiting disk 8, a cement seal is formed, and the filtrate solution flows through the filter element 4 into the cavity of the column above the housing 1, In the process

five

5 o

„

S

about

a decrease in pressure behind the casing to the formation on the check valve 7, a pressure difference of opposite sign occurs, i.e. in the direction of the shoe columns. Under the action of this pressure, the check valve 7 loads the cement seal with additional force. With a small amount of this force, the cement seal completely absorbs the load and, therefore, fixes the check valve 7 in the closed position. If the force is sufficiently large, the cement seal deforms because its shear in the pipe is impossible due to the presence of a restrictive disk 8. Compressing cement compaction with an increased load causes additional compaction of the cement mass with the release of the dispersion medium through the flushing holes in the limiting disk 8. As the resistance increases Capacity to compress the cement mass increases proportionally. Its permeability is almost equal. Zero. Thus, the breakthrough of the squeezing liquid into the shoe part of the column is eliminated completely.

The resistance of the cement mass increases as long as it is acted upon by an active compressive load transmitted by the squeezing fluid; therefore, the smallest distance between the casing and the limiting disk is determined by the maximum displacement value of the check valve in the open position. The greatest distance is limited by the need to achieve maximum compaction of the cement mass when the valve is fully opened.

The greatest possible magnitude of the displacement of the gate Lh should be greater than or equal to the deformation L of the cement mass in the cavity between the saddle and the limit

3-14

with a maximally possible compressive load, i.e.

Uh7f l. ,

The maximum overpressure from a number of wells possible in the practice of building a well is 160 µg / cm. It was established experimentally that: under the influence of this pressure, the valve, compressing the cement seal with height h, caused a reduction of 20%, i.e. by the value of bj equal to

3h 0,2h,

where h is the initial height of the cement seal, is equal to the distance between the valve seat and the limiting disk.

Given a value of 4h, having a specific value for a valve of a particular size, you can determine h from the expression

h 5 / Jh.

Thus, the value of h, as the height of the space by the slow saddle and the limiting ring, is represented by the dependence

.

For example, in the design of a typical disc valve for a casing with a diameter of 146 mm, the slide is allowed to move downward when fully opened by 30 mm.

From this it follows that it is possible to attain the greatest completion of the process with a cement mass height h equal to 54h, i.e.

h

g - 150 MM.

0

five

five

0

0

five

For larger check valves, a larger displacement of the valve is provided. Nap. For example, in the valve for a column of 245 mm, the offset is 50 mm. In this case, h 250 mm.

Claims (1)

The effectiveness of the proposed device is determined by reducing the costs and time spent on well testing and restoring the tightness of the casing shoe. Invention Formula A device for cementing casing strings, including a housing with an axial channel filled in with it and peripheral openings with filter elements, diaphragms and diaphragms installed in the latter, a squeeze plug, pins mounted over the diaphragms with the possibility of axial displacement and placement of diaphragms during interaction pins with push. a stopper and a check valve installed in the axial channel of the housing, characterized in that, in order to increase reliability in operation, it is provided with a support disk with axial holes made therein installed under the housing, and the filter elements are filled in the form of a hollow cylinder placed between the housing and a supporting disk, and the upper end of the hollow cylinder is rigidly connected to the body, and the lower one - to the supporting disk.