阅读说明：本技术 一种自适应预充填陶粒防砂筛管及自适应方法 (Self-adaptive pre-filled ceramsite sand control screen pipe and self-adaptive method ) 是由 董长银 周玉刚 甘凌云 宋洋 李志芬 于乐香 王卫阳 周博 刘亚宾 于 2021-03-25 设计创作，主要内容包括：本发明提供一种自适应预充填陶粒防砂筛管,由内至外依次包括：基管,内层滤网,外层滤网,位于内层滤网与外层滤网之间的自解堵和自压实预充填陶粒层,套设在外层滤网外侧的外保护罩；所述的自解堵和自压实预充填陶粒层包括预充填陶粒层和用于压实、解堵预充填陶粒层的自适应调整机构,预充填陶粒层内填充有人造陶粒。本发明与现有的常规预充填筛管相比,具有自压实功能,能够长期保持预充填陶粒处于密实充填状态；能够保持稳定的挡砂精度和挡砂效果；具有自解堵和自恢复功能,能够保持预充填陶粒不被过度堵塞,保持挡砂介质层良好的流通性能和油气井产能,延长预充填筛管的防砂有效期,提高总体防砂生产效果。(The invention provides a self-adaptive pre-filled ceramsite sand control screen pipe, which sequentially comprises the following components from inside to outside: the device comprises a base pipe, an inner filter screen, an outer filter screen, a self-unblocking and self-compacting pre-filled ceramsite layer positioned between the inner filter screen and the outer filter screen, and an outer protective cover sleeved outside the outer filter screen; the self-plugging-removing and self-compacting pre-filled ceramsite layer comprises a pre-filled ceramsite layer and a self-adapting adjusting mechanism for compacting and plugging-removing the pre-filled ceramsite layer, wherein artificial ceramsite is filled in the pre-filled ceramsite layer. Compared with the conventional prefilled sieve tube, the self-compacting sieve tube has the self-compacting function, and can keep the prefilled ceramsite in a compact filling state for a long time; the stable sand blocking precision and the sand blocking effect can be kept; the self-plugging-removing and self-recovering functions are realized, the pre-filled ceramsite can be kept from being excessively plugged, the good circulation performance of the sand blocking medium layer and the productivity of an oil-gas well are kept, the sand prevention validity period of the pre-filled sieve tube is prolonged, and the overall sand prevention production effect is improved.)

1. A self-adaptive pre-filled ceramsite sand control screen pipe sequentially comprises from inside to outside:

the base pipe is provided with a flow guide hole communicated with the interior of the base pipe;

an inner layer filter screen sleeved outside the base pipe;

an outer layer filter screen sleeved outside the base pipe;

a self-unblocking and self-compacting pre-filled ceramsite layer positioned between the inner filter screen and the outer filter screen;

an outer protective cover sleeved outside the outer filter screen;

the self-plugging-removing and self-compacting pre-filled ceramsite layer comprises a pre-filled ceramsite layer and a self-adapting adjusting mechanism for compacting and plugging-removing the pre-filled ceramsite layer, wherein artificial ceramsite is filled in the pre-filled ceramsite layer.

2. The self-adaptive pre-filled ceramsite sand control screen pipe according to claim 1, wherein the self-adaptive adjusting mechanism comprises a spring, a spring fixing base, an inner side sliding guide rail and an outer side sliding guide rail; the inside sliding guide rail sets up on the parent tube outer wall, and outside sliding guide rail is located the outside on pre-filled haydite layer, for holding the space on pre-filled haydite layer between inside sliding guide rail and the outside sliding guide rail, is provided with spring removal end cover respectively at the both ends on pre-filled haydite layer, and spring removal end cover is between inside sliding guide rail and outside sliding guide rail and along inboard sliding guide rail, outside sliding guide rail slip, and the spring is located between spring fixed baseplate and the spring removal end cover.

3. The self-adaptive pre-filled ceramsite sand control screen pipe according to claim 2, wherein the spring fixing base is sleeved on the base pipe and fixed at one end of the base pipe, and the end part of the outer sliding guide rail is fixed on the fixing base.

4. The self-adaptive pre-filled ceramsite sand control screen pipe according to claim 2, wherein 4 sliding guide rails are arranged on the outer side, are consistent with the axial direction of the base pipe, and are uniformly distributed at intervals on the outer periphery of the pre-filled ceramsite; the inboard sliding guide is provided with 4, and is unanimous with parent tube axial direction, at the even interval distribution of parent tube periphery.

5. The self-adaptive pre-filled ceramsite sand control screen pipe according to claim 2, wherein the springs are metal spiral compression springs, 1 spring is arranged, the springs are sleeved outside the inner sliding guide rail, the diameter of each spring is 4-6mm, the middle diameter of each spring is 6mm added to the outer diameter of the base pipe of the screen pipe, and the free length of each spring is 1-3 times of the length of the self-adaptive adjusting mechanism.

6. The adaptive pre-filled ceramsite sand control screen pipe according to claim 1, wherein the top ends of the sections of the inner sliding guide rail and the outer sliding guide rail are both wedge-shaped.

7. The self-adaptive pre-filled ceramsite sand control screen pipe according to claim 1, wherein the constant diameter particle size of the artificial ceramsite in the pre-filled ceramsite layer is determined according to the median value and the uniformity coefficient of the sand particle size of the stratum, and specifically comprises the following steps:

when the median d50 of the sand particle size of the stratum is less than 60 mu m, the particle size range of the artificial ceramsite is 0.25-0.35 mm.

When the median d50 of the formation sand particle size is between 60 and 80 mu m, the particle size range of the artificial ceramsite is 0.35 to 0.45 mm.

When the median d50 of the formation sand particle size is between 80 and 100 mu m, the particle size range of the artificial ceramsite is 0.45 to 0.55 mm.

The median d50 of the ground layer sand particle size is between 100 and 120 mu m, and the particle size range of the artificial ceramsite is 0.55-0.65 mm.

When the median d50 of the formation sand particle size is between 120 and 135 μm, the particle size range of the artificial ceramsite is 0.65-0.75 mm.

When the median d50 of the formation sand particle size is 135-155 μm, the particle size range of the artificial ceramsite is 0.75-0.85 mm.

When the median d50 of the formation sand particle size is between 155 and 170 mu m, the particle size range of the artificial ceramsite is 0.85-0.95 mm.

The median d50 of the ground layer sand particle size is between 170 and 190 mu m, and the particle size range of the artificial ceramsite is 0.95-1.05 mm.

When the median d50 of the formation sand particle size is 190-210 μm, the particle size range of the artificial ceramsite is 1.05-1.15 mm.

When the median d50 of the formation sand particle size is between 210 and 230 μm, the particle size range of the artificial ceramsite is 1.15-1.25 mm.

When the median d50 of the formation sand particle size is more than 230 mu m, the particle size range of the artificial ceramsite is 1.25-1.45 mm.

8. The adaptive pre-filled ceramsite sand control screen according to claim 1, wherein the thickness of the pre-filled ceramsite layer is greater than 20 mm.

9. The adaptive pre-filled ceramsite sand control screen according to claim 8,

the thickness of a pre-filled ceramsite layer is 35-40mm in a severe sand production or high-yield oil and gas well (the flow rate of fluid is high, and the invasion of stratum sand is severe), or a heavy oil well or a gas well;

in the oil-gas well with slight sand production and low yield, the thickness of the pre-filled ceramsite layer is 20-30 mm;

the borehole or the casing pipe is small in size, and the thickness of the pre-filled ceramsite layer is 20-25 mm;

for the condition that the production system has higher sand prevention requirements, the thickness of the pre-filled ceramsite layer is 35-40 mm;

for reservoirs with high shale content, the thickness of the pre-filled ceramsite layer is 25-30mm in order to avoid excessive plugging.

10. The method for self-unblocking and self-compacting by utilizing the self-adaptive pre-filled ceramsite sand control screen pipe comprises the following steps:

s1: setting springs at two ends of a sand control screen pipe pre-filled ceramsite layer to be in a semi-compressed state; in the normal production process, because the semi-compression state spring has the characteristic of tending to elongation, longitudinal compression acting force is generated on the pre-filled ceramsite layer, when the self-filled ceramsite layer is arranged and recombined under the action of fluid impact to generate a destabilization phenomenon, the longitudinal compression acting force of the spring compacts the pre-filled ceramsite layer, so that the destabilized filling layer is quickly compacted and is maintained in a stable state again, and the self-compaction effect is realized;

s2: after the pore throat of the sand blocking medium of the pre-filled ceramsite layer is blocked by stratum sand, the permeability and the fluidity are both reduced, so that the pressure in the cavity of the pre-filled layer is increased, the increased pressure compression spring retracts, the space of the cavity of the pre-filled layer is increased, under the action of fluid impact, the sand blocking medium of the pre-filled ceramsite layer is unstable, the space of the pore throat is increased, stratum sand particles intruding into the blockage are washed by fluid and carried through the holes of the base pipe to be discharged, and the effects of dredging, blocking self-cleaning and self-unblocking are realized.

Technical Field

The invention relates to a self-adaptive pre-filled ceramsite sand control screen pipe and a self-adaptive method, belonging to the technical field of underground sand control completion tools for oil and gas exploitation.

Background

Loose sandstone oil and gas reservoirs in China and the world are widely distributed, and reserves and yield of the loose sandstone oil and gas reservoirs are dominant at present. One of the major troublesome problems faced in the exploitation of unconsolidated sandstone oil and gas reservoirs is sand production from oil and gas wells, which causes damage to production equipment and a substantial reduction in production. In recent years, experimental development and exploitation of natural gas hydrate reserves at home and abroad are also gradually carried out. In the natural gas hydrate reservoir, most of the cementing materials of rock particles of the reservoir are hydrates, and a great amount of sand is produced due to the loss of the cementing effect after the reservoir is mined and decomposed. For the sand production problem of the oil and gas reservoir, sand prevention measures are required to be taken for normal exploitation; for the fine sand (the grain size is 50 mu m) of the loose sandstone reservoir of petroleum and natural gas, especially for the ultra-fine sand (the grain size reaches 10-15 mu m) of the hydrate reservoir of natural gas, the sand control is very difficult at present.

Among the sand control methods, gravel pack type and independent mechanical screen type sand control methods are dominant. The gravel filling sand prevention is to fill quartz sand or ceramsite in a mechanical sieve tube, a sleeve or a shaft annulus and a near well reservoir, and to use a porous medium formed by stacking filling particles to play roles in blocking sand and guiding flow; the independent mechanical screen pipe sand control is that a mechanical screen pipe is hung at the position, right opposite to a production layer, of a well bottom, and the screen pipe allows fluid to pass but can block formation sand, so that the aim of preventing the formation sand from entering a shaft is fulfilled; the sand control process of the mechanical sieve tube is simple in technology and convenient to construct. Mechanical sand screens are key downhole devices in early sand control completions or later sand control. The traditional gravel pack type and independent mechanical sieve tube type sand control cannot meet the production requirement on the comprehensive sand control effect of a natural gas hydrate argillaceous powder fine sand reservoir which has serious sand production, high argillaceous content and small formation sand grain diameter.

The pre-packed gravel sand control screen is an important type of sand control screen and is widely applied to sand control operation of oil wells, gas wells and natural gas hydrate wells. The prior pre-filled sand control screen pipe is characterized in that quartz sand or artificial ceramsite with a certain particle size range is filled between two layers of slots or wires, and the sand control of an independent mechanical screen pipe and the sand control of gravel filling are combined to play a better sand control role. It still has some problems:

(1) a pore structure formed by solid particle materials (quartz sand gravel or artificial ceramsite) pre-filled in the sieve tube is easily adsorbed and blocked by clay mud, fine sand grains, thick oil and the like produced along with fluid in a reservoir; after the sand screen pipe is blocked, the permeability of the medium of the sand screen pipe can be greatly reduced, the yield of an oil-gas well is seriously damaged, the service life of the sand screen pipe is shortened, and the integral sand control effect is poor. Because the pre-filling material is completely fixed and blocked in the existing pre-filling sieve tube, the sieve tube lacks self-cleaning capability, and the circulation capability of the sieve tube is reduced and is difficult to recover after the formation sand invades and blocks.

(2) The pre-packed solid particles typically have a size within a certain range (e.g., 20-40 mesh, 30-60 mesh) and are non-uniform in size. After sand control casting, the pre-filled solid particle material can move under the impact of fluid so as to be arranged and recombined, so that the structure of the pre-filled layer is gradually loosened, the pore throat size is increased, and the sand blocking effect is gradually reduced.

(3) After the pre-filled sieve tube is blocked or the structure is impacted to be loose and lose the sand blocking effect, the sand prevention of the pre-filled sieve tube is failed; the corresponding measure is to pull out the sieve tube and carry out the sand control operation again. Finally, the sand control validity period of the prior pre-filled sieve tube is short, and the sand control cost of the oil-gas well is high.

Chinese patent document CN204827393U is a pre-packed sand control screen pipe, which realizes sand control to an oil well, is particularly suitable for casing sand control construction of a heavy oil thermal recovery highly-deviated well, and can prolong the sand control period. The sand control screen pipe comprises a central pipe and an inner wire winding pipe, wherein the central pipe is provided with a liquid flow hole, the inner wire winding pipe is arranged outside the central pipe, a lower bearing cap and an upper pressing cap are respectively fixed at two ends of the central pipe and used for installing a pre-filling layer and an outer wire winding pipe, a compaction compensation mechanism is arranged between the upper part of the pre-filling layer and the upper pressing cap, the upper end of the outer wire winding pipe is connected with the compaction compensation mechanism through a connecting sleeve, pre-tightening force is applied to the pre-filling layer, and the compaction of the pre-filling layer is ensured; although the pre-filling sand control screen pipe can compress a pre-filling layer, ensure the compaction degree of the pre-filling layer and improve the strength of the pre-filling layer, the position of the lower bearing cap is fixed, only the upper pressing cap can slide in the compensation sleeve to compress the filling layer, the lower bearing cap can only compress downwards by virtue of external force, the self-adaptive adjustment of the device cannot be realized, namely, the self-adjusting function of automatically compensating compaction or retracting according to the condition of the pre-filling layer cannot be realized, and the self-unblocking function and the self-compacting function cannot be realized.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a self-adaptive pre-filled ceramsite sand control screen pipe and a self-adaptive method.

Interpretation of terms:

the spring is in a semi-compressed state: is half the stroke of the projectile from the natural elongation state to the maximum compression state.

The invention achieves the following aims:

1. the self-compensating compaction or retraction self-adjustment can be automatically compensated according to the condition of the pre-filled layer, and the self-unblocking and self-compaction functions are realized;

2. the self-cleaning blockage removal after the sieve tube is blocked is realized, the instability of the pre-filled gravel in the production process is automatically resisted, the compaction degree of ceramsite particles is kept, the filling stability is improved, and the stable sand blocking effect is kept.

3. The sand control validity period of the pre-filled sand control screen pipe is greatly prolonged, and the comprehensive sand control effect is improved.

In order to achieve the above purpose, the invention is realized by the following technical scheme:

a self-adaptive pre-filled ceramsite sand control screen pipe sequentially comprises from inside to outside:

the base pipe is provided with a flow guide hole communicated with the interior of the base pipe;

an inner layer filter screen sleeved outside the base pipe;

an outer layer filter screen sleeved outside the base pipe;

a self-unblocking and self-compacting pre-filled ceramsite layer positioned between the inner filter screen and the outer filter screen;

an outer protective cover sleeved outside the outer filter screen;

the self-plugging-removing and self-compacting pre-filled ceramsite layer comprises a pre-filled ceramsite layer and a self-adapting adjusting mechanism for compacting and plugging-removing the pre-filled ceramsite layer, wherein artificial ceramsite is filled in the pre-filled ceramsite layer.

According to the optimization of the invention, the self-adaptive adjusting mechanism comprises a spring, a spring fixing base, an inner side sliding guide rail and an outer side sliding guide rail; the inside sliding guide rail sets up on the parent tube outer wall, and outside sliding guide rail is located the outside on pre-filled haydite layer, for holding the space on pre-filled haydite layer between inside sliding guide rail and the outside sliding guide rail, is provided with spring removal end cover respectively at the both ends on pre-filled haydite layer, and spring removal end cover is between inside sliding guide rail and outside sliding guide rail and along inboard sliding guide rail, outside sliding guide rail slip, and the spring is located between spring fixed baseplate and the spring removal end cover.

According to the invention, the spring fixing base is sleeved on the base pipe and fixed at one end of the base pipe, and the end part of the outer sliding guide rail is fixed on the fixing base.

According to the invention, preferably, 4 sliding guide rails are arranged on the outer side, the sliding guide rails are consistent with the axial direction of the base pipe, and are uniformly distributed at intervals on the outer periphery of the pre-filled ceramsite layer.

Preferably, the inner sliding guide rail is provided with 4 sliding guide rails which are consistent with the axial direction of the base pipe and are uniformly distributed at intervals on the periphery of the base pipe.

According to the invention, the spring is preferably a metal spiral compression spring, 1 spring is arranged and sleeved outside the inner sliding guide rail, the diameter of the spring is 4-6mm, the middle diameter is 6mm added to the outer diameter of the sieve tube base tube, and the free length of the spring is 1-3 times of the length of the self-adaptive adjusting mechanism.

According to the invention, the top ends of the cross sections of the inner sliding guide rail and the outer sliding guide rail are both wedge-shaped. The stability of being connected with the removal end cover is guaranteed.

According to the optimization of the invention, the constant diameter grain size of the artificial ceramsite in the pre-filled ceramsite layer is determined according to the median value and the uniformity coefficient of the stratum sand grain size, and the method comprises the following specific steps:

when the median d50 of the sand particle size of the stratum is less than 60 mu m, the particle size range of the artificial ceramsite is 0.25-0.35 mm.

When the median d50 of the formation sand particle size is between 60 and 80 mu m, the particle size range of the artificial ceramsite is 0.35 to 0.45 mm.

When the median d50 of the formation sand particle size is between 80 and 100 mu m, the particle size range of the artificial ceramsite is 0.45 to 0.55 mm.

The median d50 of the ground layer sand particle size is between 100 and 120 mu m, and the particle size range of the artificial ceramsite is 0.55-0.65 mm.

When the median d50 of the formation sand particle size is between 120 and 135 μm, the particle size range of the artificial ceramsite is 0.65-0.75 mm.

When the median d50 of the formation sand particle size is 135-155 μm, the particle size range of the artificial ceramsite is 0.75-0.85 mm.

When the median d50 of the formation sand particle size is between 155 and 170 mu m, the particle size range of the artificial ceramsite is 0.85-0.95 mm.

The median d50 of the ground layer sand particle size is between 170 and 190 mu m, and the particle size range of the artificial ceramsite is 0.95-1.05 mm.

When the median d50 of the formation sand particle size is 190-210 μm, the particle size range of the artificial ceramsite is 1.05-1.15 mm.

When the median d50 of the formation sand particle size is between 210 and 230 μm, the particle size range of the artificial ceramsite is 1.15-1.25 mm.

When the median d50 of the formation sand particle size is more than 230 mu m, the particle size range of the artificial ceramsite is 1.25-1.45 mm.

Preferably according to the invention, the thickness of the pre-filled ceramic layer is greater than 20 mm.

The thickness of a pre-filled ceramsite layer is 35-40mm in a severe sand production or high-yield oil and gas well (the flow rate of fluid is high, and the invasion of stratum sand is severe), or a heavy oil well or a gas well;

in the oil-gas well with slight sand production and low yield, the thickness of the pre-filled ceramsite layer is 20-30 mm;

the borehole or the casing pipe is small in size, and the thickness of the pre-filled ceramsite layer is 20-25 mm;

for the condition that the production system has higher sand prevention requirements, the thickness of the pre-filled ceramsite layer is 35-40 mm;

for reservoirs with high shale content, the thickness of the pre-filled ceramsite layer is 25-30mm in order to avoid excessive plugging.

A screen pipe base pipe: providing structural load bearing and support to the unitary screen. The pipe wall of the base pipe is provided with a flow guide hole, so that the integral strength of the sieve pipe is ensured, and an oil gas inflow channel is provided through the hole; inner layer net: clinging to the outer wall of the base pipe, playing the role of isolating the base pipe from the pre-filling material and preventing the pre-filling material from flowing into the base pipe through the holes of the base pipe. Inner side slide rail: sliding supports and guides are provided for the spring to move the end caps. Pre-filling a ceramic particle layer: artificial ceramsite with certain thickness and particle size is pre-filled, so that the effects of blocking formation sand and keeping the circulation are achieved. Spring fixed base: for mounting and securing one end of the spring. The spring moves the sealing end cover: used for connecting and fixing the moving end of the spring and realizing the matching with the inner sliding guide rail. A spring: providing the power for axially compacting the pre-filled ceramic particle layer. Outer slide rail: welded to the spring fixing base and providing the outer sliding support and the guide rail for the spring moving sealing end cover. Outer filter screen: hug closely the prefill layer outside and the outer protective cover is inboard, plays outer protective cover and prefill material, prevents that prefill material from leaking the outside effect outer protective cover of protective cover: the function of protecting the medium in the sieve tube is achieved; the wall of the protective cover is provided with holes for providing a fluid inflow channel.

The method for self-unblocking and self-compacting by utilizing the self-adaptive pre-filled ceramsite sand control screen pipe comprises the following steps:

s1: setting springs at two ends of a sand control screen pipe pre-filled ceramsite layer to be in a semi-compressed state; in the normal production process, because the semi-compression state spring has the characteristic of tending to elongation, longitudinal compression acting force is generated on the pre-filled ceramsite layer, when the self-filled ceramsite layer is arranged and recombined under the action of fluid impact to generate a destabilization phenomenon, the longitudinal compression acting force of the spring compacts the pre-filled ceramsite layer, so that the destabilized filling layer is quickly compacted and is maintained in a stable state again, and the self-compaction effect is realized;

s2: after the pore throat of the sand blocking medium of the pre-filled ceramsite layer is blocked by stratum sand, the permeability and the fluidity are both reduced, so that the pressure in the cavity of the pre-filled layer is increased, the increased pressure compression spring retracts, the space of the cavity of the pre-filled layer is increased, under the action of fluid impact, the sand blocking medium of the pre-filled ceramsite layer is unstable, the space of the pore throat is increased, stratum sand particles intruding into the blockage are washed by fluid and carried through the holes of the base pipe to be discharged, and the effects of dredging, blocking self-cleaning and self-unblocking are realized.

The self-plugging removal and self-compaction principle of the self-adaptive pre-filled ceramsite sand control screen pipe is as follows:

1. the self-compaction principle is as follows: and when the sieve tube is assembled, the spring springs at the upper end and the lower end of the pre-filled ceramic particle layer are set to be in a semi-compressed state. In the normal production process, because the spring bullet in the semi-compression state at both ends has the extension characteristic of tendency about in the prefilled haydite layer, can produce the longitudinal compression effect to prefilled haydite layer, be equivalent to prefilled haydite layer by the compaction. And once the pre-filled ceramsite layer is arranged and recombined under the action of fluid impact to generate a destabilization phenomenon, the destabilized filling layer can be quickly compacted and can be maintained in a stable state again under the compaction action of the spring. Fig. 3 illustrates the above process and the self-compaction principle.

2. The self-unblocking principle is as follows: under the normal circulation condition of the sieve tube, the pressure in the cavity of the sieve tube prefill layer is lower; when the pore throat of the sieve tube prefilled ceramsite sand-blocking medium is blocked by stratum sand, the permeability and the fluidity of the sieve tube prefilled ceramsite sand-blocking medium are reduced, and the pressure is caused to rise in the containing cavity of the prefilled layer. The increased pressure can compress the spring to retract, so that the space of the cavity of the pre-filling layer is enlarged; under the action of fluid impact, the pre-filled ceramsite particles in the enlarged space are unstable and the pore throat space is enlarged; under the condition, sand particles intruding into the blocked stratum can be flushed by fluid and carried through the holes of the base pipe to be discharged, so that the effects of dredging, self-cleaning and self-unblocking are achieved. Once the blockage is relieved and the flow is recovered, the pressure in the cavity of the pre-filling layer is reduced to a normal level, and the spring returns to the original semi-compressed state, so that the ceramsite in the pre-filling layer returns to the original compacted state. Until finally the sand stabilizing bridge frame is formed on the outer part of the screen pipe, and the inner part of the screen pipe is always kept unblocked. Fig. 4 shows the above process and the self-unblocking principle.

Aiming at the self-plugging-removing principle and the sieve tube structure of the sieve tube, the invention needs to be specially strengthened and explained as follows: under normal conditions, the sand blocking process of the sieve tube is as follows: in the early stage of screen sand control production, the fine formation sand particles enter the inside of the screen to produce invasion blocking, and meanwhile, the coarse formation sand particles are bridged outside the screen until a stable bridge outside the screen is formed (fig. 4 d). The stratum sand bridge outside the screen pipe is a natural phenomenon and also a basic principle and a necessity of the screen pipe for controlling the sand. However, plugging inside the screen during the formation of the bridge outside the screen is undesirable because the plug permeability is extremely low, which can significantly reduce the well productivity. The self-plugging-removing function of the sieve tube provided by the invention is just to remove the plugging of the inside of the sieve tube medium in the process.

The thickness and the particle size of the pre-filled ceramsite layer are preferably obtained in a sand blocking simulation experiment by simulating a large number of conventional oil and gas reservoirs and various particle size stratum sands of hydrate reservoirs by an inventor, so that each structural parameter of the pre-filled sand control screen pipe can adapt to the geological and production conditions of conventional oil and gas and natural gas hydrate argillaceous silty fine sand reservoirs, the high sand blocking performance and the high circulation performance can be considered in the sand control process, after the screen pipe is blocked, a blocking object is removed by a self-cleaning mechanism to recover the circulation performance of the screen pipe, the effective blocking and the efficient oil and gas flow guiding of argillaceous silty fine sands are realized, and meanwhile, the stability of the pre-filled layer can be effectively protected by an outer protection cover and an outer blocking screen net, and the risk of erosion damage is reduced.

Aiming at the equal-diameter ceramsite filling, the ceramsite with a certain particle size range is selected and filled during actual processing and manufacturing, so that the processing and screening errors are considered, the processing and manufacturing are facilitated, and the cost is reduced. Because in field practice it is difficult and costly to screen solid particles of perfectly equal diameter.

Even so, the packed particle size range according to the present invention is narrow and very close to the desired isodiametric particle size. Taking the equal diameter grain diameter of 0.6mm as an example, the porcelain granules with the grain diameter of 0.55-0.65mm are allowed to be filled for the convenience of processing and manufacturing and cost reduction. For comparison, the particle size range of the ceramsite corresponding to the equivalent average particle size of 0.6mm in the existing prepacked sieve tube is 0.4-0.8 mm. Such a large particle size range can result in large variations in pore throat structure and sand retention accuracy after particle destabilization and reorganization.

The invention has the following technical characteristics and advantages:

1. the sand control screen pipe is provided with a self-adapting adjusting mechanism, and the self-adapting adjusting mechanism comprises a spring, a spring fixing base, an inner side sliding guide rail and an outer side sliding guide rail; the spring mechanism in the original semi-compression state has the characteristic of tending to extend, and can generate the longitudinal compaction effect on the pre-filled ceramsite layer. Once the pre-filled ceramsite layer is arranged and recombined under the action of fluid impact to generate a destabilization phenomenon, the destabilized filling layer can be quickly compacted and can be maintained in a stable state again through the compaction action of the spring. Compared with the conventional pre-filled sieve tube, the pre-filled ceramsite has the advantages that the pre-filled ceramsite can be kept in a compact filling state for a long time, stable sand blocking precision and sand blocking effect are kept, and the sand prevention validity period of the pre-filled sieve tube is prolonged.

2. The sand control screen pipe is provided with a self-adaptive adjusting mechanism and has a self-unblocking function. When the sieve tube prefilled ceramsite sand blocking medium is blocked, the pressure in the filling containing cavity can be increased due to poor pressure, and the sealing end of the driving spring compresses the spring, so that the containing cavity space of the prefilled layer is enlarged; the pre-filled ceramsite particles are unstable, and the pore throat space is enlarged; the sand particles intruding into the blocked stratum can be flushed by fluid and carried through the holes of the base pipe to be discharged, so that the effects of dredging, self-cleaning and self-unblocking are achieved. Once the blockage is relieved, the pressure is reduced, and the ceramsite in the pre-filling layer can be restored to the original compaction state under the action of the spring. Compared with the conventional pre-filled sieve tube, the self-plugging-removing and self-recovering sieve tube has the advantages that the pre-filled ceramsite can be prevented from being excessively plugged through the self-plugging-removing and self-recovering functions, the good circulation performance of the sand blocking medium layer is kept, the productivity of an oil-gas well is kept, the sand prevention validity period of the pre-filled sieve tube is prolonged, and the overall sand prevention production effect is improved.

3. The pre-filled ceramsite layer of the sand control screen pipe is the constant-diameter artificial ceramsite, so that the pore throat size after final compaction is stable no matter how the ceramsite particles are unstable and arranged and recombined in the self-plugging removal and self-compaction processes of the screen pipe, and the stable liquidity and the sand blocking effect are ensured. Compared with the traditional pre-filled sieve tube filled with solid particles with larger particle size range, the filling of the invention can better ensure stable sand blocking effect and sand blocking precision, avoid the change and reduction of sand blocking capability after the instability recombination of the filling layer and has better comprehensive sand prevention effect.

4. The design method of the grain diameter and the thickness of the pre-filled ceramsite layer of the sand control screen pipe recommends reasonable grain diameter and filling thickness of the pre-filled ceramsite without passing through production conditions and stratum sand design. The recommended design parameters are verified based on experimental evaluation, and the sand control effect of the self-adaptive pre-filled ceramsite sand control screen pipe provided by the invention under different conditions is ensured.

Drawings

FIG. 1 is a schematic diagram of the overall structure of the self-adaptive pre-filled ceramsite sand control screen pipe;

FIG. 2 is a cross-sectional view B-B of FIG. 1;

FIG. 3 is a schematic diagram of the self-compacting process and principle of the self-adaptive pre-filled ceramsite sand control screen pipe according to the present invention;

FIG. 4 is a schematic diagram of the self-plugging removal process and principle of the self-adaptive pre-filled ceramsite sand control screen pipe according to the invention;

FIG. 5 is a schematic view of a partial structure of the self-adaptive pre-filled ceramsite sand control screen according to the present invention.

In the figure, 1, a base pipe; 2. an inner layer filter screen; 3. an inner slide rail; 4. pre-filling a ceramsite layer; 5. a spring fixing base; 6. moving the sealing end cover; 7. a spring; 8. an outer slide rail; 9. an outer layer filter screen; 10. an outer protective cover; 11. and (4) flow guide holes.

Detailed Description

The invention is further defined in the following, but not limited to, the figures and examples in the description.

Example 1

A self-adaptive pre-filled ceramsite sand control screen pipe is structurally shown in figures 1 and 2 and sequentially comprises the following components from inside to outside:

the base pipe 1 is provided with a flow guide hole 11 communicated with the interior of the base pipe;

an inner layer filter screen 2 sleeved outside the base pipe 1;

an outer layer filter screen 9 sleeved outside the base pipe 1;

the inner and outer layer filter screens are single-layer metal wires vertically staggered mesh nets, the meshes are square, the length and width of the meshes are about 2/3 of the grain size of the pre-filled ceramsite, the diameter of the metal wires is 0.3-0.5mm, and the material is 316L steel.

A self-unblocking and self-compacting pre-filled ceramsite layer positioned between the inner filter screen and the outer filter screen;

an outer protective cover 10 sleeved outside the outer layer filter screen 9; the outer protective cover is made of 304 steel, the thickness of the outer protective cover is 1-1.5mm, and a spiral seam punching structure is selected.

The self-plugging and self-compacting pre-filled ceramsite layer 4 comprises a pre-filled ceramsite layer 4 and a self-adapting adjusting mechanism for compacting and plugging removing the pre-filled ceramsite layer, wherein artificial ceramsite is filled in the pre-filled ceramsite layer.

The self-adaptive adjusting mechanism comprises a spring 7, a spring fixing base 5, an inner side sliding guide rail 3 and an outer side sliding guide rail 8; the 3 guide rails of inboard slip set up on 1 outer wall of parent tube, outside sliding guide 8 is located the outside on pre-filled ceramsite layer, for holding the space on pre-filled ceramsite layer between inboard sliding guide 3 and the outside sliding guide 8, both ends on pre-filled ceramsite layer are provided with spring removal end cover 6 respectively, spring removal end cover 6 is between inboard sliding guide 3 and outside sliding guide 8 and along inboard sliding guide, outside sliding guide slides, spring 7 is located between spring fixed baseplate and the spring removal end cover. The spring be metal spiral compression spring, be provided with 1, the cover is established in the inboard sliding guide outside, the diameter of spring is 4mm, the pitch diameter adds 6mm for the screen pipe base pipe external diameter, the free length of spring is 2 times of self-adaptation adjustment mechanism length. The spring fixing base is sleeved on the base pipe and fixed at one end of the base pipe, and the end part of the outer sliding guide rail is fixed on the fixing base. The fixed base 5 is welded to the outer wall of the base pipe 1 for suspending the spring 7. The length of the self-adaptive adjusting mechanism is 0.3 m.

The outer sliding guide rails 8 are provided with 4 guide rails which are consistent with the axial direction of the base pipe and are uniformly distributed at intervals on the outer periphery of the pre-filled ceramsite layer.

The inner side sliding guide rails 3 are provided with 4 sliding guide rails which are consistent with the axial direction of the base pipe and are uniformly distributed at intervals on the periphery of the base pipe.

The top ends of the cross sections of the inner sliding guide rail 3 and the outer sliding guide rail 8 are both wedge-shaped. The stability of being connected with the removal end cover is guaranteed.

The isometric particle size of the artificial ceramsite in the pre-filled ceramsite layer is determined according to the median value and the uniformity coefficient of the sand granularity of the stratum, and the method comprises the following steps:

when the median d50 of the sand particle size of the stratum is less than 60 mu m, the particle size range of the artificial ceramsite is 0.25-0.35 mm.

When the median d50 of the formation sand particle size is between 60 and 80 mu m, the particle size range of the artificial ceramsite is 0.35 to 0.45 mm.

When the median d50 of the formation sand particle size is between 80 and 100 mu m, the particle size range of the artificial ceramsite is 0.45 to 0.55 mm.

The median d50 of the ground layer sand particle size is between 100 and 120 mu m, and the particle size range of the artificial ceramsite is 0.55-0.65 mm.

When the median d50 of the formation sand particle size is between 120 and 135 μm, the particle size range of the artificial ceramsite is 0.65-0.75 mm.

When the median d50 of the formation sand particle size is 135-155 μm, the particle size range of the artificial ceramsite is 0.75-0.85 mm.

When the median d50 of the formation sand particle size is between 155 and 170 mu m, the particle size range of the artificial ceramsite is 0.85-0.95 mm.

The median d50 of the ground layer sand particle size is between 170 and 190 mu m, and the particle size range of the artificial ceramsite is 0.95-1.05 mm.

When the median d50 of the formation sand particle size is 190-210 μm, the particle size range of the artificial ceramsite is 1.05-1.15 mm.

When the median d50 of the formation sand particle size is between 210 and 230 μm, the particle size range of the artificial ceramsite is 1.15-1.25 mm.

When the median d50 of the formation sand particle size is more than 230 mu m, the particle size range of the artificial ceramsite is 1.25-1.45 mm.

The thickness of a pre-filled ceramsite layer is 35-40mm in a severe sand production or high-yield oil and gas well (the flow rate of fluid is high, and the invasion of stratum sand is severe), or a heavy oil well or a gas well;

in the oil-gas well with slight sand production and low yield, the thickness of the pre-filled ceramsite layer is 20-30 mm;

the borehole or the casing pipe is small in size, and the thickness of the pre-filled ceramsite layer is 20-25 mm;

for the condition that the production system has higher sand prevention requirements, the thickness of the pre-filled ceramsite layer is 35-40 mm;

for reservoirs with high shale content, the thickness of the pre-filled ceramsite layer is 25-30mm in order to avoid excessive plugging.

Example 2

The difference between the self-adaptive pre-filled ceramsite sand control screen pipe and the sand control screen pipe in the embodiment 1 is that:

the spring is metal spiral compression spring, is provided with 1, and the cover is established in the inboard sliding guide outside, and the diameter of spring is 6mm, and the pitch diameter adds 6mm for the screen pipe base pipe external diameter, and the free length of spring is 3 times of self-adaptation adjustment mechanism length. The spring fixing base is sleeved on the base pipe and fixed at one end of the base pipe, and the end part of the outer sliding guide rail is fixed on the fixing base. The fixed base 5 is welded to the outer wall of the base pipe 1 for suspending the spring 7. The length of the self-adaptive adjusting mechanism is 0.5 m.

Example 3

The method for self-unblocking and self-compacting by utilizing the self-adaptive pre-filled ceramsite sand control screen pipe comprises the following steps:

s1: setting springs at two ends of a sand control screen pipe pre-filled ceramsite layer to be in a semi-compressed state; in the normal production process, because the semi-compression state spring has the characteristic of tending to elongation, longitudinal compression acting force is generated on the pre-filled ceramsite layer, when the self-filled ceramsite layer is arranged and recombined under the action of fluid impact to generate a destabilization phenomenon, the longitudinal compression acting force of the spring compacts the pre-filled ceramsite layer, so that the destabilized filling layer is quickly compacted and is maintained in a stable state again, and the self-compaction effect is realized; as shown in figure 3 of the drawings,

s2: after the pore throat of the sand blocking medium of the pre-filled ceramsite layer is blocked by stratum sand, the permeability and the fluidity are both reduced, so that the pressure in the cavity of the pre-filled layer is increased, the increased pressure compression spring retracts, the space of the cavity of the pre-filled layer is increased, under the action of fluid impact, the sand blocking medium of the pre-filled ceramsite layer is unstable, the space of the pore throat is increased, stratum sand particles intruding into the blockage are washed by fluid and carried through the holes of the base pipe to be discharged, and the effects of dredging, blocking, self-cleaning and self-unblocking are realized, as shown in fig. 4.