CN1108731A - Technology for overcoming U-shape tube effect in the course of pouring cement and apparatus thereof - Google Patents

Abstract

When putting in the casing, the pressure-down flow-limiting device is jointed in series to the top end of the lower portion mechanism of the casing. After the casing and top joint section have been put in, the assembly of bowling short section prefilled ith large and small two sealing balls is jointed in series between the top joint section and cement head. In accordance with the demand, the liquid columnpressure difference between interior and exterior of the casing is regulated through putting in two sealing balls successively to decrease such condition in the well cementation process, as the pressure of loop empty liquid column increasing in early stage and decreasing in later stage caused by pouring cement, and the loop empty liquid returning upward speed being too high in early stage and too low in later stage caused there from, thus the serious erosion of well wall caused by too high returning speed and the displacement efficiency decreation due to too low speed in later stage of

Description

Technology for overcoming U-shape tube effect in the course of pouring cement and apparatus thereof

The present invention relates to oil, overcome the technology and the device of U-shaped tube effect in system's well drilling and cementing cement injection processes such as ore deposit.

In the cementing process, owing to inject the drilling fluid density that the interior cement slurry density of institute's setting of casing surpasses the sleeve pipe outer ring space, thereby form the fluid column differential static pressure, along with the increase of injecting cement slurry volume, this differential static pressure is increasing, when this pressure reduction in the early stage less than well in the liquid required pressure that circulates consuming time, it is the effect of the low surface pump pressure of landing only, and when it is consuming time greater than this required pressure, to force the annulus fluid upward velocity to increase, this just causes annulus fluid excessive to borehole wall erosion quantity, causes hole instability, causes the cementing quality variation; On the other hand, because the inside and outside differential static pressure of sleeve pipe is poor greater than normal required dynamic pressure, this just forces regurgitation volume on the outer liquid of pipe to pump into amount in the sleeve pipe greater than ground, causes formation dead band in the sleeve pipe.In replacing the mud process, the liquid that is pumped in the sleeve pipe need at first be used to be full of this space, just makes the annular space cement paste to return on the normal speed after being full of gradually, in the meantime because annular space cement paste upward velocity is low excessively, it is low to cause replacing effect, thereby also makes the cementing quality variation.

The purpose of this invention is to provide a kind of technology and device that overcomes U-shaped tube effect in the cementing process.

The object of the present invention is achieved like this: the technology that overcomes U-shaped tube effect in the cementing process is as follows: the upper end that during setting of casing the step-down current-limiting apparatus is serially connected in institute's setting of casing substructure, after having descended sleeve pipe and landing joint, giving the dropping sub summary that installs big or small two setting balls earlier is serially connected between landing joint and the cementing head, opening surface pump then circulates, in the low process of surface pump pressure drop, cement paste in the sleeve pipe and the mud of annular space differential static pressure≤normal circulation is pressed consuming time, bead sets on the flow-limiting valve of step-down current-limiting apparatus (7), the pitching lead time can be by the length of sleeve pipe, bead in sleeve pipe landing speed and the cover tube fluid downstream rate calculate, in the high process of surface pump voltage rise, when begin to cause inside and outside the sleeve pipe that from returning out annular space at the bottom of the sleeve pipe and rising to certain altitude differential static pressure is reduced to normal circulation when pressing the consumption desirable value from cement injection to cement paste, big ball is set the interior pipe top of step-down current-limiting apparatus, tube hub hole in setting, suppress the disconnected pin that hangs, pipe comes off with the lower part together with it in making, and throwing the big ball lead time can be by the length of sleeve pipe, big ball in sleeve pipe landing speed and the speed of cover tube fluid calculate.

Overcome that the used device of U-shaped tube effect technology includes dropping sub assembly and step-down current-limiting apparatus two parts in the cementing process, the dropping sub assembly is located at cased top, the step-down current-limiting apparatus is located at the upper end of institute's setting of casing substructure, described its outer tube of step-down current-limiting apparatus is made up of casing coupling (1) and outer tube (2), screw in annular hanging head (3) in box bottom, box cupling upper end, interior pipe (5) is connected with hanging head (3) by hanging pin (4), interior pipe (5) is provided with discharge orifice (6), discharge orifice (6) matches with flow-limiting valve (7), establish flow-limiting valve (7) in the interior tube hub hole, compression spring (8) and spring base (9), the center of flow-limiting valve (7) is empty, spring base (9) is connected with interior pipe (5), the spring base lower end edge is axially opened 1-100 fluid course (11), described dropping sub assembly comprise structural form duplicate about two bypass dress, release mechanism, dress minor diameter ball in one of them bypass mechanism, dress major diameter ball in another bypass mechanism, the bypass pipe nipple (14) that connects with pipe nipple is arranged in the middle of the pipe nipple (13), clamping nut (15), both are connected, seal groove is opened in the bypass end, in establish seal washer (16), with the clamping nut center line is the center line perforate, in establish ball pushing rod (18), the left side of ball pushing rod (18) is stretched in the bypass pipe nipple (14) with the ring washer of horizontal positioned (20) wherein and is linked to each other, establish 1-5 sealing ring (19) between ball pushing rod (18) and the clamping nut, the radially perforate of external part termination of ball pushing rod (18), the interior alignment pin (22) that inserts is placed ball (21) in the annular ring (20) in bypass pipe nipple (14).

Use technology of the present invention and device, can be artificial as required determine, regulate the inside and outside fluid column pressure reduction of sleeve pipe, reduce the annular space head of liquid that causes because of cementing in the well cementation process and change (increase in advance, later stage reduces) and the annulus fluid upward velocity that causes thus earlier excessive, the situation that the back is too small, avoiding returning the too high borehole wall that causes of speed at the cementing initial stage washes away serious phenomenon and cementing later stage and replaces the mud initial stage to return the low excessively phenomenon that causes displacement efficiency to reduce of speed, and can be by the fluid that manually gives fixed speed control annular space, the fixed speed of returning is given in realization, avoided fluctuating, helped improving cementing quality because of the speed of returning that the U-shaped tube effect causes.

Be described in detail technical solution of the present invention below in conjunction with accompanying drawing.

Fig. 1 is a step-down current-limiting apparatus structural representation.

Fig. 2 is a dropping sub assembly structure schematic diagram.

During setting of casing; the step-down current-limiting apparatus is serially connected in the upper end of institute's setting of casing substructure; after having descended sleeve pipe and landing joint; after having descended sleeve pipe and landing joint; giving the dropping sub assembly that installs big or small two balls earlier is serially connected between landing joint and the cementing head; press the circulation of normal procedure turn on pump then; mud is at this moment because the not pitching of step-down current-limiting apparatus center-aisle; fluids such as mud can be passed through by centre bore smoothly; consequent flow resistance is minimum; before the mud circulation process finishes, arrive during the formal cement injection; in the low process of surface pump pressure drop; cement paste in the sleeve pipe and the mud of annular space differential static pressure≤normal circulation is pressed consuming time; bead sets on the flow-limiting valve 7 of step-down current-limiting apparatus; the pitching lead time can be by the length of sleeve pipe; bead in sleeve pipe landing speed and the cover tube fluid downstream rate calculate; the process of sending into of bead is to transfer to alignment pin 22; spin off protective cover 17; press ball pushing rod 18 inward; in process of press in, do not rotate; make annular ring 20 keep level as far as possible; when ball pushing rod 18; after annular ring 20 and ball 21 move to certain position toward the dropping sub center; ball 21 enters the vertical channel position of dropping sub; because the action of gravity of ball self and the momentum effect of mud; deviate from from annular ring 20; and then ball pushing rod 18 outwards moved to the origin-location; by protective cover 17; insert good alignment pin 22; the process of pitching for the first time finishes; ball is by own wt and mud thrust; flow-limiting valve 7 in giving the arrival step-down current-limiting apparatus of fixing time sets the place; set flow-limiting valve 7 centre bores; this moment, flow-limiting valve 7 was because the effect of the last thrust of spring 8; have only when fluid pressure in the upper sleeve post during greater than the last thrust of spring 8; flow-limiting valve 7 just begins to move down; discharge orifice 6 is open-minded; the annular space of liquid between discharge orifice 6 inside pipes 5 and outer tube 2 reaches and flows downward thus in the sleeve pipe; in this process because the effect of flow-limiting valve 7; the sleeve pipe internal pressure that the U-shaped tube effect is caused increases by flow-limiting valve 7 to be offset; guarantee that liquid is continuous state in the sleeve pipe, so casing annulus liquid upward velocity depends on that all the time ground pumps into speed.

In the high process of surface pump voltage rise, when begin to cause inside and outside the sleeve pipe that from returning out annular space at the bottom of the sleeve pipe and rising to certain altitude differential static pressure is reduced to normal circulation when pressing the consumption desirable value from cement injection to cement paste, send into big ball again by the program of sending into bead the above-mentioned first time, the pitching lead time can be by the length of sleeve pipe, big ball in sleeve pipe landing speed and the downstream rate of cover tube fluid calculate, set the interior pipe upper end of step-down stream device when big ball after, set on it, pipe 5 centre bores are shut in making, the sleeve pipe internal pressure is elevated to when a certain amount of, hanging pin 4 is cut off, interior pipe 5 falls down from hanging head 3 places with the lower part together with it downward disengagement, overlap tube fluid through hanging head 3 centre bores this moment, annular space between interior pipe 5 and the outer tube 2 flows downward, interior pipe promptly loses the step-down metering function, has avoided for the mud later stage because the pump pressure that the effect of flow-limiting valve 7 causes rising.

Claims (2)

1, a kind of technology that overcomes U-shaped tube effect in the cementing process, when it is characterized in that setting of casing, the step-down current-limiting apparatus is serially connected in the upper end of institute's setting of casing substructure, after having descended sleeve pipe and landing joint, giving the dropping sub summary that installs big or small two setting balls earlier is serially connected between landing joint and the cementing head, opening surface pump then circulates, in the low process of surface pump pressure drop, cement paste in the sleeve pipe and the mud of annular space differential static pressure≤normal circulation is pressed consuming time, bead sets on the flow-limiting valve of step-down current-limiting apparatus (7), the pitching lead time can be by the length of sleeve pipe, bead in sleeve pipe landing speed and the cover tube fluid downstream rate calculate, in the high process of surface pump voltage rise, when begin to cause inside and outside the sleeve pipe that from returning out annular space at the bottom of the sleeve pipe and rising to certain altitude differential static pressure is reduced to normal circulation when pressing the consumption desirable value from cement injection to cement paste, big ball is set the interior pipe top of step-down current-limiting apparatus, tube hub hole in setting, suppress the disconnected pin that hangs, pipe comes off with the lower part together with it in making, and throwing the big ball lead time can be by the length of sleeve pipe, big ball in sleeve pipe landing speed and the speed of cover tube fluid calculate.

2, a kind of device that uses the described technology of claim 1, it is characterized in that this device includes dropping sub assembly and step-down current-limiting apparatus two parts, the dropping sub assembly is located at cased top, the step-down current-limiting apparatus is located at the upper end of institute's setting of casing substructure, described its outer tube of step-down current-limiting apparatus is made up of casing coupling (1) and outer tube (2), screw in annular hanging head (3) in box bottom, box cupling upper end, interior pipe (5) is connected with hanging head (3) by hanging pin (4), interior pipe (5) is provided with discharge orifice (6), discharge orifice (6) matches with flow-limiting valve (7), establish flow-limiting valve (7) in the interior tube hub hole, compression spring (8) and spring base (9), the center of flow-limiting valve (7) is empty, spring base (9) is connected with interior pipe (5), the spring base lower end edge is axially opened 1-100 fluid course (11), described dropping sub assembly comprise structural form duplicate about two bypass dress, release mechanism, dress minor diameter ball in one of them bypass mechanism, dress major diameter ball in another bypass mechanism, the bypass pipe nipple (14) that connects with pipe nipple is arranged in the middle of the pipe nipple (13), clamping nut (15), both are connected, seal groove is opened in the bypass end, in establish seal washer (16), with the clamping nut center line is the center line perforate, in establish ball pushing rod (18), the left side of ball pushing rod (18) is stretched in the bypass pipe nipple (14) with the ring washer of horizontal positioned (20) wherein and is linked to each other, establish 1-5 sealing ring (19) between ball pushing rod (18) and the clamping nut, the radially perforate of external part termination of ball pushing rod (18), the interior alignment pin (22) that inserts is placed ball (21) in the annular ring (20) in bypass pipe nipple (14).

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