SU1221328A1 - Deep-well gun for hydraulic fracturing of formations - Google Patents

Description

one

The invention relates to devices for hydraulic fracturing and can be used in the extraction of oil, gas and geothermal waters.

The aim of the invention is to increase the power of the hydrostatic impact on the formation and prevent damage to the casing,

Fig. 1 shows a device for hydraulic fracturing in the process of descending into the well (deep gun), a general view; Fig. 2 illustrates the installation of a separation plug and a circulation valve above the gas-liquid chamber.

The device has an implosion chamber (a hollow body) 1 with a plunger 2 containing a check valve 3 with a membrane 4 in the upper part, a gas-liquid chamber formed by section 5 of the tubing column containing a shock liquid column 6 and a column 7 of compressed gas, and limited mobile a separating plug 8 at the top and a membrane 4 from below, the lower adapter 9 of the circulation valve 10 is screwed onto the gas-liquid chamber 5, and the retaining ring 13 is clamped between adapter 9 and adapter 11 with slotted windows 12. Adapter 11 is connected to the column tubing (tubing) 14.

The movable separator plug 8 has in its lower cylindrical part 30-40 holes with a diameter of 3-4 mm and contains a set of annular cuffs 15 (3-4 pieces) fixed to the body with the help of spacer sleeves 16 and a threaded nut 17, as well as an elastic nipple 18, elastically reciprocating perforated section of plug 8 (instead of a nipple system, there may be a check valve, for example, of pilot type).

Elements of the device are assembled during their descent into the well. Before descending into the well of the housing 1, a relative vacuum is previously created in it by a known method. Dp this, for example, to the housing 1 with the plunger 2 from the bottom is attached a pipe not less than Yume's length with a plugged end and the housing and the pipe are filled with water. Then the case is hermetically sealed from above with a membrane 4, the plug of the lower pipe is removed, while the water.

2213282

1. Flows out through the check valve 3 of the plunger 2 and a vacuum is created in the housing 1, and in the lower pipe there is a Hume of the water column, to compensate for atmospheric pressure. This pipe is disconnected from the housing 1 and lowered into the well.

A gas-liquid chamber 5, which is a tubing section 14 having an internal diameter equal to the internal diameter of body 1. In this chamber, the height of the liquid column 6 is 15-30 m and the height 15 of the h column 7, the compressed gas injected through the nozzle 19 is selected so that just before the destruction of the membrane 4, the height of this column is also equal to 1520 30 m. This condition is met when

h, h, u

0

0

where hj is 15-30 m, 5 Р liquid density in

well, kg / m, g - acceleration of the force of tin,

m / s2;

Hj is the depth of installation of gas-liquid Ks1mery in the well for fracturing, MJ

u (, S. excess pressure at the wellhead for membrane destruction. Pa, P - preliminary (initial) gas pressure in the gas-liquid chamber. Pa.

A circulation valve with a stop ring is connected to the gas-liquid chamber 5, by installing a separating plug 8 directly below it. A gas pipe (nitrogen or air) is introduced into the gas-liquid chamber 5 through the pipe 19, the axial channel and the elastic nipple (valve) of the separating plug 8. in it the preliminary (initial) gas pressure P i., Unscrew the nozzle 19 from the casing of the separation plug 8 and increase the tubing string 14 on the top of the circulation valve, the circulation valve is placed against the bottom of the reservoir, as the well goes down to 5 the separator plug 8 descends lower and lower into the pressure of the column 7 of compressed gas in the gas-liquid chamber 5 is aligned with the hydrostatic 5

tical pressure of the liquid column in the well 20.

The back circulation from the annular space of the well 20 through the circulation valve into the tubing 14 of the mud in the well 20 is replaced with a light liquid and the filter interval is intensively washed, for example, with a hydrocarbon solvent (in oil wells) or an aqueous surfactant solution (in geothermal wells),

After that, the device is raised together with the tubing string 14 so that the plunger 2 of the housing 1 is opposed to the depth at which it is intended to pronounce the hydraulic fracture of the formation 21.

By injecting pumping liquid into the tubing string 14 (in this case, due to the pressure drop, the valve 10 closes, separating the tubing channel 14 from the well 20) increases the pressure on the membrane 4 by the amount P, and destroys it.

After the destruction of the membrane 4, the shock column 6 of liquid from the gas-liquid chamber falls into the housing 1 and is accelerated in it by the column 7 of compressed gas and hits the plunger 2 at high speed, which easily separates from the housing 1 and, in turn, hits the liquid under in the area of the reservoir 21. (To remove the plunger 2 and the separator plug 8 when lifting the tubing string 14 to the housing 1 from the bottom, a lantern with a gripping bottom can be attached to the thread).

The rate of fall of shock column 6 of fluid into housing 1 on each segment of the path of travel z is determined by the effect of gravity mg of this column, the pressure force P of the compressed gas and, taking into account the friction force on the length P of the shock liquid column, is determined by the formula

(Pfg + Pa

B1

-) id

L RE

 Gy - density of shock column

liquids, kg / m, f - height of the liquid shock column in the gas-liquid chamber, m;

g — acceleration of the force of gravity, m / s2;

Pj - pressure of compressed gas in

gas-liquid chamber at the time of destruction of the membrane. Pa j

2 is the height of the column of compressed gas in the gas-liquid chamber at the time of the destruction of the membrane, Mj

Z is the height of the implosion chamber (hollow tube) —the length of the path of the fall of the shock column of liquid in the implosion chamber — from the destruction of the membrane to the plunger (segments of the path of movement of the shock column of liquid after the destruction of the membrane), m;

d is the internal diameter of the cross section of the gas-liquid and implosive chambers, m.

IL is the liquid drop resistance coefficient for tourV 0.3164. boulder mode "in -.

Mkё

for water 0.025. The water hammer pressure is calculated using the formula N.E. Zhukovsky

va

 R

where a y, 1200 m / s is the velocity of propagation of the longitudinal elastic, pressure fluctuations in the well.

five

Since the lateral hydraulic pressure impulse to the near-wellbore zone of the formation 21 significantly exceeds the value of the vertical rock pressure, the existing fractures expand and new fractures occur in the formation.

The pressure impulse is spent on expansion and the creation of fractures in the formation, therefore, elastic pressure waves - dilutions in the well do not propagate or have a small bulk, which do not pose a danger to the well lining. However, these vibrations in the area of the reservoir are absorbed by the compressed gas pushed out of the body into the well.

5 immediately after a water hammer.

After the destruction of the membrane, the annular gates are closed

armature at the wellhead and determine the injectivity of the reservoir 21. With a satisfactory injectivity of the formation, 3-10 m of highly concentrated hydrochloric acid (in carbonate rocks) or clay acids (in terrigenous deposits) are pumped into it at a rate of 0.2-0.5 m per 1 m of seam thickness. The well is left with the valves closed for 30-60 minutes to react the acid with the formation rock, and then open

valves and lowering the level of liquid in the tubing string 14 at 500-800 m compressor clear the near-wellbore zone of the reservoir from the reaction products of the acid with the rock while

call flow from the reservoir.

Editor M. 1 (itkina

1560/38

Circulation 548 Subscription VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Branch ShSh Patent, Uzhgorod, st. Project, 4

Compiled by I. Cap

Tehred L. Oleynik Proof-reader S. Cherni

Claims (1)

DEPTH GUN FOR HYDRAULIC RUPTURE OF THE LAYER, containing a tubing string installed in the casing of the well with a side channel communicating its cavity with the annulus, a hollow body rigidly connected to the lower end of the tubing string with a membrane in the upper part and a plunger in the lower part forming an airtight chamber, characterized in that, in order to increase the power of hydropercussion to the formation and prevent damage to the casing, it is equipped with a circulation valve ohm for overlapping side channel tubing string and installed in the pump-kompressor.nyh pipe between the circulation valve and membrane an axially movable separating stopper, wherein the cavity of tubing between the partition plug and the membrane is filled with fluid from the pressurized gas. SU „1221328 eleven