CN110630213A - Ultra-deep narrow-gap liner cementing method with stratum invader - Google Patents
Ultra-deep narrow-gap liner cementing method with stratum invader Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 45
- 239000012530 fluid Substances 0.000 claims abstract description 106
- 239000002002 slurry Substances 0.000 claims abstract description 41
- 238000010276 construction Methods 0.000 claims abstract description 31
- 230000009545 invasion Effects 0.000 claims abstract description 11
- 238000001125 extrusion Methods 0.000 claims abstract description 8
- 238000005553 drilling Methods 0.000 claims description 62
- 239000004568 cement Substances 0.000 claims description 40
- 238000006073 displacement reaction Methods 0.000 claims description 37
- 238000011010 flushing procedure Methods 0.000 claims description 15
- 238000004364 calculation method Methods 0.000 claims description 11
- 230000015572 biosynthetic process Effects 0.000 claims description 7
- 125000006850 spacer group Chemical group 0.000 claims description 7
- 125000004122 cyclic group Chemical group 0.000 claims description 3
- 238000007789 sealing Methods 0.000 abstract description 8
- 230000005465 channeling Effects 0.000 abstract description 5
- 230000006641 stabilisation Effects 0.000 abstract description 2
- 238000011105 stabilization Methods 0.000 abstract description 2
- 239000007788 liquid Substances 0.000 description 18
- 238000002955 isolation Methods 0.000 description 14
- 238000013461 design Methods 0.000 description 12
- 238000005406 washing Methods 0.000 description 8
- 239000011440 grout Substances 0.000 description 5
- 239000012267 brine Substances 0.000 description 4
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 230000033228 biological regulation Effects 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 238000005457 optimization Methods 0.000 description 2
- 238000000518 rheometry Methods 0.000 description 2
- 238000011144 upstream manufacturing Methods 0.000 description 2
- 235000008708 Morus alba Nutrition 0.000 description 1
- 240000000249 Morus alba Species 0.000 description 1
- 208000035217 Ring chromosome 1 syndrome Diseases 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000012797 qualification Methods 0.000 description 1
- 230000002311 subsequent effect Effects 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 239000002023 wood Substances 0.000 description 1
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B33/00—Sealing or packing boreholes or wells
- E21B33/10—Sealing or packing boreholes or wells in the borehole
- E21B33/13—Methods or devices for cementing, for plugging holes, crevices or the like
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/02—Subsoil filtering
- E21B43/10—Setting of casings, screens, liners or the like in wells
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Abstract
The invention relates to a method for cementing a tail pipe with an ultra-deep narrow gap and a stratum invader. The well cementation method comprises the following steps: 1) a tail pipe is put into the shaft to the position to be well-fixed, and an invaded body in the well is discharged; 2) injecting well cementing fluid into the well to replace the well cementing fluid in place; when the well cementing fluid is injected, controlling construction discharge and construction pressure according to a pressure window at the deep well where stratum invasion occurs; 3) and (4) carrying out pressure building and backward extrusion. The invention provides a method for cementing a tail pipe with an ultra-deep narrow gap and a stratum invader, which comprises the steps of firstly judging a pressure window and performing balanced pressure cementing under the pressure window so as to ensure the pressure stabilization of the stratum and reduce the overflow of the invader; and after the slurry replacement is finished, the invader which is possible to move upwards is squeezed into the stratum through a pressure-building reverse squeezing measure, so that the sealing quality of the overlapped section is ensured. The well cementation method can better seal the tail pipe with the ultra-deep narrow gap of the invader, improve the sealing quality and effectively prevent channeling.
Description
Technical Field
The invention belongs to the field of well cementation of oil and gas wells, and particularly relates to a method for cementing a tail pipe with an ultra-deep narrow gap and a stratum invader.
Background
At present, a multi-stage structure is often adopted in the structural design of a well body aiming at the ultra-deep well at home and abroad. The last-time well cementation usually adopts a tail pipe suspension mode, and open hole stratums and overlapped sections need to be sealed during well cementation. Because well structure restriction, overlap section annular space gap is narrower, and the cement sheath that the grout formed is thinner, under the condition that there is the invasion body in the stratum, overlap section is because the invasion of stratum fluid causes the losing seal easily, brings the potential safety hazard for later stage well drilling and oil gas development.
The application publication number of the Chinese invention patent application CN108240196A discloses a liner cementing method for controlling the annular equivalent density of a pressure sensitive stratum, which is based on the lowest equivalent density for keeping a shaft stable and the highest equivalent density for preventing the stratum from being lost, and reduces the density of drilling fluid before cementing so as to reduce the risk of loss and improve the replacement efficiency of cement slurry.
Aiming at the ultra-deep narrow gap liner cementing with stratum invaders, the cementing method can not effectively prevent the invaders from channeling, so that the sealing quality of the overlapped section is poor.
Disclosure of Invention
The invention aims to provide a method for cementing a tail pipe with an ultra-deep narrow gap with a stratum invader, which aims to solve the problem that the conventional cementing method has poor anti-channeling effect on the invader.
In order to achieve the purpose, the technical scheme of the ultra-deep narrow gap liner cementing method with stratum invaders is as follows:
an ultra-deep narrow gap liner cementing method with stratum invaders comprises the following steps:
1) a tail pipe is put into the shaft to the position to be well-fixed, and an invaded body in the well is discharged;
2) injecting well cementing fluid into the well to replace the well cementing fluid in place; when the well cementing fluid is injected, controlling construction discharge and construction pressure according to a pressure window at the deep well where stratum invasion occurs;
the calculation formula of the pressure window is as follows: rhozgh≤P≤ρzgh+Pc (1)；
In formula (1), P-pressure window, unit MPa; rhozDrilling fluid density in g/cm3(ii) a h-well depth where invasion of the formation occurs, in m; pc-bearing value in MPa; the pressure-bearing value is the lowest value according to the pressure value when the pressure-bearing value is increased according to the well cementation requirement and the pressure value when the pressure-bearing process is leaked;
the calculation formula of the value added for well cementation needs to be as follows: pd＝Σρighdi+ρzghzd+Pfg0-ρzgh (2)；
In the formula (2), Pd-increased need for cementing, ρiDensity of each cementing fluid to be run into the well in g/cm3；hdi-the height of the annular cementing fluid in m after the slurry is replaced; h iszd-the height of the drilling fluid in the annulus that has not been displaced after the slurry has been displaced in place, in m; pfg0-maximum cyclic friction in MPa during cementing;
p is obtained by calculation according to the following formulafcThen from PfcDetermining the construction displacement;
Pfc+Σρighi+ρzghz≤Pmax (3)；
Pfc＝Pfg-Pfz (4)；
in formulae (3) and (4), Pfz、Pfg、PfcRespectively are circulation friction resistance before well cementation, circulation friction resistance during well cementation and the difference value of the circulation friction resistance during well cementation and before well cementation, and the unit is MPa; h isi-the height of each cementing fluid entering the annulus in m; h isz-the height of the annulus un-displaced drilling fluid in m; pmaxThe upper limit value of the pressure window;
3) and (4) carrying out pressure building and backward extrusion.
The invention provides a method for cementing a tail pipe with an ultra-deep narrow gap and a stratum invader, which comprises the steps of firstly judging a pressure window and performing balanced pressure cementing under the pressure window so as to ensure the pressure stabilization of the stratum and reduce the overflow of the invader; and after the slurry replacement is finished, the invader which is possible to move upwards is squeezed into the stratum through a pressure-building reverse squeezing measure, so that the sealing quality of the overlapped section is ensured. The well cementation method can better seal the tail pipe with the ultra-deep narrow gap of the invader, improve the sealing quality and effectively prevent channeling.
In the occasions where leakage does not occur before well cementation, a relatively abundant pressure window is generally provided, and the requirements of well cementation construction can be conveniently met by arranging the isolating fluid, the cement slurry and the displacing fluid. In this case, preferably, in step 2), no loss occurs before cementing, and the cementing fluid includes a spacer fluid, a cement slurry, and a displacement fluid.
In the case of leakage before well cementation, the pressure window is narrow, and in order to avoid the phenomenon of stratum leakage by pressure, preferably, in the step 2), leakage occurs before well cementation, the well cementation liquid comprises flushing liquid, spacer fluid, cement slurry and displacement liquid, and the density of the flushing liquid is lower than that of drilling fluid used during drilling. By using the cleaning fluid with the density lower than that of the drilling fluid, the liquid column pressure can be effectively reduced, and then the pressure-balanced well cementation can be realized. If the reasonable flushing fluid amount can not reduce the liquid column pressure more, the pilot low-density drilling fluid can be injected to reduce the liquid column pressure before well cementation.
Further, in order to avoid the situation that the cleaning fluid cannot be introduced into the intrusion body or the high-pressure water layer stably under pressure, it is preferable that the annular space is pressurized at the time of replacement, and the magnitude of the pressurized pressure is calculated by the following formula:
Pmin≤P2+Pfc+Σρighi+ρzghz≤Pmax (5)；
in the formula, PminThe lower limit value of the pressure window is expressed in MPa; p2The pressure for pressurizing the annulus is given in MPa. By pressurizing the annular space, the pressure of the stratum can be guaranteed to be stable, and the overflow phenomenon is reduced or avoided.
Drawings
FIG. 1 is a schematic view of the pressure-bearing state of an ultra-deep narrow-gap liner cementing method of the present invention in embodiment 1;
FIG. 2 is a schematic view of the construction state of an ultra-deep narrow gap liner cementing method of the present invention in embodiment 1;
FIG. 3 is a schematic diagram of a reverse circulation well-flushing and pressure-building state in embodiment 1 of the ultra-deep narrow gap liner cementing method of the present invention;
in the figure, 1-pipe, 2-surface casing, 3-technical casing, 4-open hole formation, 5-invader well depth; 6-well completion depth; 7-drilling tool, 8-tail tube; 9-plug setting; 10-a hanger; 11-cement slurry return-up position; 12-upper plug, 13-cement sheath.
Detailed Description
The following examples are provided to further illustrate the practice of the invention.
The specific embodiment of the ultra-deep narrow gap liner cementing method with stratum invaders comprises the following steps:
example 1
The method for cementing a 1-11 well in an oil field by using a liner with an ultra-deep narrow gap and a stratum invader in the embodiment adopts a four-stage structure, and the last-stage cementing adoptsAnd tail pipe well cementation, wherein the middle well completion depth is 7576m, the narrowest unilateral annular space is only 11.1mm, and the well ground isThe mass structure mulberry tree group has an invader, brine invasion occurs for many times in the drilling process, brine is discharged for many times during the drifting period, meanwhile, leakage and oil gas display are carried out, and the concrete well cementation steps are as follows:
(1) and (3) judging a pressure window: the pressure window is judged according to the formula (1):
ρzgh≤P≤ρzgh+Pc (1)；
wherein, P-pressure window, unit MPa; rhozDrilling fluid density in g/cm3(ii) a h-the depth of the well where the invasion of the formation occurs (invader well depth position), in m; pc-bearing value in MPa; the pressure-bearing value is the lowest value according to the pressure value when the pressure-bearing value is increased according to the well cementation requirement and the pressure value when the pressure-bearing process is leaked;
the calculation formula of the value added for well cementation needs to be as follows: pd＝Σρighdi+ρzghzd+Pfg0-ρzgh (2)；
In the formula (2), Pd-increased need for cementing, ρiDensity of each cementing fluid to be run into the well in g/cm3；hdi-the height of the annular cementing fluid in m after the slurry is replaced; h iszd-the height of the drilling fluid in the annulus that has not been displaced after the slurry has been displaced in place, in m; pfg0-maximum cyclic friction in MPa during cementing; the calculation of the circulating friction resistance is carried out by referring to SY-T5480-1992 cement rheological design and calculating Pfg0At a safe return speed V during drillingzCalculations are made for the displacement of the cycles.
When the well is drilled to 7239m, loss occurs (logging shows the position of the depth of an invader, the value is taken as h in the formula (1)), and the density of the drilling fluid is 1.65g/cm during the drifting circulation3And the value of the increase of the well cementation requirement can be calculated to be 5.2MPa according to the known data related to well drilling. The pressure is applied before the well is fixed (schematically shown in figure 1), and leakage occurs after 4.0MPa (the value is P in the formula (1))c)。
In the well structure shown in fig. 1, the gauge and the well depth position of the conduit 1 are 508mm × 50m, the gauge and the well depth position of the surface casing 2 are 298.5mm × 2004.30m, the gauge and the well depth position of the technical casing 3 are 219.1mm × 6693.11m, and the well depth 5 position of the invader in the open hole stratum 4 is 7239 m; the position of the middle well completion depth 6 is 7576 m; during pressure bearing, the drilling tool 7 is positioned in the technical casing 3, the wellhead blowout preventer is in a closed state, and 4MPa (pressure is transmitted to an open hole stratum through drilling fluid) is pressed through the drilling tool 7, so that the pressure value when leakage occurs is tested in the pressure bearing process.
The pressure window P of the well depth position of the invader can be calculated by the formula (1) as follows: p is more than or equal to 117.17MPa and less than or equal to 121.17 MPa. Correspondingly, the equivalent density ρ at the invader well depth position is: 1.65g/cm3≤ρ≤1.706g/cm3。
(2) Optimization of slurry column structure (cementing fluid): according to the related requirements of the well drilling design and the actual drilling condition, the cement slurry consumption of 20m is obtained according to the length of the sealing section3The density of the cement slurry (determined according to the design requirements of the well) is 1.88-1.91g/cm3。
The pad fluid (spacer fluid) is designed to be 2 times of the annular volume of the open hole, specifically 14m, on the principle of ensuring that the drilling fluid can be effectively displaced3. The density value of the pad fluid is generally the middle value of the density of the drilling fluid and the density of cement slurry, but because of the requirement of narrow clearance on the displacement efficiency, the higher density can improve the turbulent displacement under the same condition, and the construction displacement of the ultra-deep well is limited, so the isolation fluid is designed to be injected in two sections, the former section is low-density isolation fluid (providing higher displacement efficiency), the latter section is high-density isolation fluid, and the densities of the low-density isolation fluid and the high-density isolation fluid are 1.70g/cm respectively3And 1.80g/cm3The dosage is 7m3(i.e., 1 times the open hole annulus volume).
The design of the displacement fluid is designed according to the reserved sleeve inner lower plug 150m (shown in figure 2) by taking the risk of displacement into consideration. In the slurry replacing construction process shown in FIG. 2, the specification and the well depth position of the tail pipe 8 are 168.3mm multiplied by 7558.6 m; the height of a lower plug 9 (cement plug) in the tail pipe 8 is 150 m; the well depth position of the hanger 10 is 6473.93-6377.88 m; the depth of the cement slurry at the upstream position 11 is 6177 m.
As loss occurs before cementing, the cementing fluid of the well comprises a flushing fluid to reduce the pressure of the fluid column, and the density of the flushing fluid is 1.03g/cm3In an amount of a bare eye ring1 time of empty volume (i.e. 7 m)3)。
Calculating P according to the formula (3) and the formula (4)fcThen from PfcDetermining construction displacement:
Pfc+Σρighi+ρzghz≤Pmax (3)；
Pfc＝Pfg-Pfz(4)；
in the formula, Pfz、Pfg、PfcRespectively are circulation friction resistance before well cementation, circulation friction resistance during well cementation and the difference value of the circulation friction resistance during well cementation and before well cementation, and the unit is MPa; h isi-the height of each cementing fluid entering the annulus in m; h isz-the height of the annulus un-displaced drilling fluid in m; pmaxThe upper limit value of the pressure window; pfg、PfzThe calculation method is referred to SY-T5480-1992 cement rheology design. Pfg、PfzThe construction displacement is calculated by the factors such as construction displacement, well diameter data and working fluid rheological parameters, and the other values except the construction displacement can be regarded as invariant.
According to the design parameters of the cementing fluid (flushing fluid, pad fluid, cement slurry and displacement fluid) and the formulas (2) and (3), P can be obtainedfc+117.51MPa or less 121.17MPa, namely PfcLess than or equal to 3.6 MPa. Then according to PfcThe relation with the construction displacement is calculated to obtain the construction displacement controlled at 1.1m3The construction requirement can be met within min.
(3) And (3) casing pipe descending speed control: the casing running speed is calculated according to the following formula:
wherein, V, unit m/s, casing speed; vzUnit m/s, safe return speed during drilling; q, unit l/m, average ring volume outside the sleeve; q. q.szUnit l/m, average circulation volume during drilling.
The known parameters include a safe return velocity of 1.04m/s when drilling; the average annular volume outside the sleeve is 9.36 l/m; the average annular volume during drilling is 16.28 l/m. The casing running speed is calculated and obtained according to the known parameters and is controlled to be 0.46m/s, and the well leakage in the casing running process can be effectively prevented.
(4) And (3) circulating and replacing slurry pressure control: small displacement (generally not more than 0.15 m) after the casing is in place3Min), jacking, slowly increasing the circulating discharge (meeting the construction discharge condition determined in the step (2) after the drilling fluid at the well bottom circulates to 500m above the hanger, discharging the invader before well cementation in the circulating process, wherein the circulating pressure is not more than 18MPa when the well is drifted.
Because the well has leakage, the liquid column of the well cementing liquid contains flushing liquid for reducing the pressure of the liquid column, and the annulus is pressurized to stabilize the stratum in the slurry replacing process (namely, the requirement of a pressure window at the well depth position of an invader is met). The magnitude of the pressurization is calculated as follows:
Pmin≤P2+Pfc+Σρighi+ρzghz≤Pmax (5)；
in the formula (5), PminThe lower limit value of the pressure window is expressed in MPa; p2The pressure for pressurizing the annulus is given in MPa.
Specifically, the pressure regulation and control change time is based on the ratio of the total injected slurry amount to the construction displacement of each node (divided according to the type of the well cementation fluid). The pressure regulation and control nodes mainly comprise three control nodes:
the first node is that the flushing liquid just flows out of the sleeve pipe pin until all the flushing liquid flows out of the sleeve pipe pin, and the trend range of the annular pressure increase can be calculated according to the formula (5) and the known values of the flushing liquid density, the flushing liquid annular height, the drilling fluid density and the like, and is 0-4.25 MPa;
the second node is that the isolation fluid just comes out of the casing pipe pin until all the isolation fluid comes out of the casing pipe pin, and the trend range of the annular pressure increase can be calculated according to the formula (5) and the numerical values of the known flushing fluid, the density of the isolation fluid, the annular height, the drilling fluid density and the like, and is 4.25-3.30 MPa;
the third node is a cement paste outlet pin, and the trend range of annular pressure increase is calculated to be 3.30-0MPa according to related data.
This embodiment is in accordance with Pmin＝P2+Pfc+Σρighi+ρzghzIs calculated to obtain P2Also, P can be usedmin、PmaxMiddle value P in betweenmedFrom Pmed＝P2+Pfc+Σρighi+ρzghzIs calculated to obtain P2。P2A value of 0 or negative indicates that no pressure is required to be applied to the annulus.
(5) In order to improve the channeling-preventing effect, the reverse circulation well washing is carried out after the slurry replacement is finished, and enough cement slurry is reserved in an upper plug so as to ensure that the reverse extrusion and pressure building procedures after the reverse circulation well washing can be implemented. The reverse extrusion amount is larger than the cement paste amount of the overlapped section and is not larger than the reserved cement paste amount of the upper plug.
After the replacement of the grout is finished, the amount of the reserved cement grout on the upper plug is 5.9m3The amount of cement paste in the overlapped section is 1.4m3Pulling out 7 columns of the drilling tool, and performing reverse circulation well washing; then the drilling tool 1 column is started, the well is closed and the pressure is kept to 3.5MPa (at the moment, the pressure of the annular liquid column is greater than the maximum value P of the window pressuremaxFormation fracture to perform squeeze-in), 1.4m squeeze-in3Drilling fluid (as shown in figure 3).
In the schematic diagram of the reverse circulation well washing and pressure building state shown in fig. 3, the drilling tool is lifted into the technical casing 3 to perform reverse circulation well washing, then the wellhead blowout preventer is closed, the drilling tool is used for building pressure building and reverse extrusion under the pressure of 3.5MPa, and an invader which may flee upwards is extruded into the stratum to ensure the sealing quality of the overlapped section; after the cement slurry is solidified, the cement slurry above the hanger 10 forms an upper plug 12, and the cement slurry in the annular space forms a cement sheath 13, so that the ultra-deep narrow gap liner cementing is completed.
The well is cemented according to the method of the embodiment, the quality and the high-quality rate of the well cementing of the overlapped section and the pipe shoe part of the well are 100 percent, the qualification rate of the whole well cementing is 100 percent, the annular water channeling phenomenon does not occur in the later stage of well drilling, the sound amplitude quality of the well cementing is shown in the table 1, and the well completion evaluation is good.
TABLE 1 well cementation amplitude quality of example 1
Example 2
The method for cementing a 1-4H well in an oil field by using a liner with an ultra-deep narrow gap and a stratum invader in the embodiment adopts a four-stage structure, and the last-stage cementing adoptsAnd (3) tail pipe well cementation, wherein the well completion depth is 7460m, invasion bodies exist in a Santana wood group with a geological structure of the well, brine invasion occurs for many times in the drilling process, brine is discharged for many times during the well dredging period, and leakage and oil gas display are accompanied, and the concrete well cementation steps are as follows:
(1) and (3) judging a pressure window:
when the well is drilled to 7015m, the stratum is drained, and returns with the subsequent effect display (the logging display is the well depth position of an invader, the value is h in the formula (1)), and the drilling fluid density is 1.81g/cm during the well dredging circulation3According to the known data related to well drilling, the value of 8MPa (the value is taken as P in the formula (1)) for increasing the well cementation requirement can be calculatedc) And no leakage occurs when pressure bearing is carried out before the well is fixed.
In the well structure of the well (refer to fig. 1), the specification and the well depth position of the guide pipe are 508mm multiplied by 50m, the specification and the well depth position of the surface casing are 273.1mm multiplied by 1999.3m, the specification and the well depth position of the technical casing are 193.7mm multiplied by 6838.52m, and the well depth position of the invader is 7015m in the open hole stratum; the deep position of the middle well completion is 7460 m; when bearing pressure, the drilling tool is positioned in the technical casing, the wellhead blowout preventer is in a closed state, the drilling tool is used for pressurizing to 8MPa (pressure is transmitted to an open hole stratum through drilling fluid), and no leakage occurs in the pressure bearing process.
The pressure window P of the well depth position of the invader can be calculated by the formula (1) as follows: p is more than or equal to 124.56MPa and less than or equal to 132.56 MPa. Correspondingly, the equivalent density ρ at the invader well depth position is: 1.81g/cm3≤ρ≤1.926g/cm3。
(2) Optimization of slurry column structure (cementing fluid): according to the related requirements of the well drilling design and the actual drilling condition, the cement slurry consumption of 12m is obtained according to the length of the sealing section3The density of the cement slurry (determined according to the design requirements of the well) is 1.88-1.91g/cm3。
The pad fluid (spacer fluid) is designed to be 2 times of the annular volume of the open hole, specifically 10m, on the principle of ensuring that the drilling fluid can be effectively displaced3. The density value of the pad fluid is generally the middle value of the density of the drilling fluid and the density of cement slurry, but because of the requirement of narrow clearance on the displacement efficiency, the higher density can improve the turbulent displacement under the same condition, and the construction displacement of the ultra-deep well is limited, so the isolation fluid is designed to be injected in two sections, the former section is low-density isolation fluid (providing higher displacement efficiency), the latter section is high-density isolation fluid, and the densities of the low-density isolation fluid and the high-density isolation fluid are 1.81g/cm respectively3And 1.85g/cm3The dosage is 5m3(i.e., 1 times the open hole annulus volume).
The design of the displacement fluid is designed according to the inner lower plug 150m of the reserved casing, considering the risk of displacing the empty space (refer to fig. 2). In the slurry replacing construction process, the specification and the well depth position of the tail pipe are 139.7mm multiplied by 7459 m; the height of a lower plug (cement plug) in the tail pipe is 150 m; the well depth position of the hanger is 6688.72-6684.32 m; the depth of the cement slurry at the upstream position is 6488 m.
As no leakage occurs before cementing, the cementing fluid of the well comprises isolation fluid, cement slurry and displacement fluid.
Calculating P according to the formula (3) and the formula (4)fcThen from PfcDetermining construction displacement:
Pfc+Σρighi+ρzghz≤Pmax (3)；
Pfc＝Pfg-Pfz (4)；
in the formula, Pfz、Pfg、PfcRespectively are circulation friction resistance before well cementation, circulation friction resistance during well cementation and the difference value of the circulation friction resistance during well cementation and before well cementation, and the unit is MPa; h isiThe height of each well cementing liquid entering the annulus is m; h iszThe height of the drilling fluid which is not displaced in the annulus is m; pmaxThe upper limit value of the pressure window; pfg、PfzReference to the calculation methodSY-T5480-1992 design of cement rheology. Pfg、PfzThe construction displacement is calculated by the factors such as construction displacement, well diameter data and working fluid rheological parameters, and the other values except the construction displacement can be regarded as invariant.
P can be obtained according to the design parameters of the cementing fluid (spacer fluid, cement slurry and displacement fluid) and the formulas (3) and (4)fc+129.44MPa or less 132.56MPa, namely PfcLess than or equal to 3.12 MPa. Then according to PfcThe relation with the construction displacement is calculated to obtain the construction displacement controlled at 0.7m3The construction requirement can be met within min.
(3) And (3) casing pipe descending speed control: the casing running speed is calculated according to the following formula:
wherein, V, unit m/s, casing speed; vzUnit m/s, safe return speed during drilling; q, unit l/m, average ring volume outside the sleeve; q. q.szUnit l/m, average circulation volume during drilling.
Known parameters include a safe return velocity of 0.614m/s while drilling; the average annular volume outside the sleeve is 7.16 l/m; the average annular volume during drilling is 16.27 l/m. The casing running speed is calculated and obtained according to the known parameters and is controlled to be 0.221m/s, and the well leakage in the casing running process can be effectively prevented.
(4) And (3) circulating and replacing slurry pressure control: small displacement (generally not more than 0.15 m) after the casing is in place3Min), jacking, slowly increasing the circulating discharge (meeting the construction discharge condition determined in the step (2) after the drilling fluid at the well bottom circulates to 500m above the hanger, discharging the invader before well cementation in the circulating process, wherein the circulating pressure is not more than 22MPa when the well is drifted.
The well has no leakage, and annular pressurization is not needed in the well cementation process.
(5) In order to improve the channeling-preventing effect, the reverse circulation well washing is carried out after the slurry replacement is finished, and enough cement slurry is reserved in an upper plug so as to ensure that the reverse extrusion and pressure building procedures after the reverse circulation well washing can be implemented. The reverse extrusion amount is larger than the cement paste amount of the overlapped section and is not larger than the reserved cement paste amount of the upper plug.
After the replacement of the grout is finished, the amount of the reserved cement grout on the upper plug is 4.45m3The cement paste amount of the overlapped section is 1.04m3Pulling out 7 columns of the drilling tool, and performing reverse circulation well washing; then the drilling tool 1 column is started, the well is closed and the pressure is kept to 7.1MPa (at the moment, the pressure of the annular liquid column is greater than the maximum value P of the window pressuremaxFormation fracture), 1.1m of squeeze-in3Drilling fluid (the relevant process can refer to fig. 3).
When the well is cemented according to the method of the embodiment, the good quality rate of the well cementing quality of the well overlapping section and the pipe shoe part is 100%, the good quality rate of the whole well cementing is 100%, the annular water channeling phenomenon does not occur in the later stage of well drilling, the sound amplitude quality of the well cementing is shown in the table 2, and the well completion evaluation is excellent.
Table 2 well cementation amplitude quality of example 2
Claims (4)
1. An ultra-deep narrow gap liner cementing method with stratum invaders is characterized by comprising the following steps:
1) a tail pipe is put into the shaft to the position to be well-fixed, and an invaded body in the well is discharged;
2) injecting well cementing fluid into the well to replace the well cementing fluid in place; when the well cementing fluid is injected, controlling construction discharge and construction pressure according to a pressure window at the deep well where stratum invasion occurs;
the calculation formula of the pressure window is as follows: rhozgh≤P≤ρzgh+Pc (1)；
In formula (1), P-pressure window, unit MPa; rhozDrilling fluid density in g/cm3(ii) a h-well depth where invasion of the formation occurs, in m; pc-bearing value in MPa; the pressure-bearing value is the lowest value according to the pressure value when the pressure-bearing value is increased according to the well cementation requirement and the pressure value when the pressure-bearing process is leaked;
the calculation formula of the value added for well cementation needs to be as follows: pd＝Σρighdi+ρzghzd+Pfg0-ρzgh (2)；
In the formula (2), Pd-increased need for cementing, ρiDensity of each cementing fluid to be run into the well in g/cm3；hdi-the height of the annular cementing fluid in m after the slurry is replaced; h iszd-the height of the drilling fluid in the annulus that has not been displaced after the slurry has been displaced in place, in m; pfg0-maximum cyclic friction in MPa during cementing;
p is obtained by calculation according to the following formulafcThen from PfcDetermining the construction displacement;
Pfc+Σρighi+ρzghz≤Pmax (3)；
Pfc＝Pfg-Pfz (4)；
in formulae (3) and (4), Pfz、Pfg、PfcRespectively are circulation friction resistance before well cementation, circulation friction resistance during well cementation and the difference value of the circulation friction resistance during well cementation and before well cementation, and the unit is MPa; h isi-the height of each cementing fluid entering the annulus in m; h isz-the height of the annulus un-displaced drilling fluid in m; pmaxThe upper limit value of the pressure window;
3) and (4) carrying out pressure building and backward extrusion.
2. The method for cementing with an ultra-deep narrow gap liner having a formation invader according to claim 1, wherein in step 2), no loss occurs before cementing, and the cementing fluid comprises a spacer fluid, a cement slurry and a displacement fluid.
3. The method for cementing with an ultra-deep narrow gap liner in the presence of a formation invader according to claim 1, wherein in step 2), a loss occurs before cementing, and the cementing fluid comprises a flushing fluid, a spacer fluid, a cement slurry and a displacement fluid, and the density of the flushing fluid is lower than that of a drilling fluid used during drilling.
4. The method for cementing with an ultra-deep narrow gap liner having a formation invader according to claim 3, wherein the annulus is pressurized at the time of displacement, and the magnitude of the pressurized pressure is calculated by the following formula:
Pmin≤P2+Pfc+Σρighi+ρzghz≤Pmax (5)；
in the formula (5), PminThe lower limit value of the pressure window is expressed in MPa; p2The pressure for pressurizing the annulus is given in MPa.
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