CN101824970A

CN101824970A - Elastic rigid centralizer

Info

Publication number: CN101824970A
Application number: CN200910006877A
Authority: CN
Inventors: 李越
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-03-03
Filing date: 2009-03-03
Publication date: 2010-09-08

Abstract

The invention relates to an elastic rigid centralizer which mainly comprises a main body (1) , a plurality of rigid centralizing slats (2) and a plurality of plate spring centralizing sheets (3), wherein the rigid centralizing slats (2) and the plate spring centralizing sheets (3) are evenly distributed on the circumference on the main body (1).Each plate spring centralizing sheet (3) is installed in the chute of each rigid centralizing slat (2), thereby forming the novel casing centralizer which has the characteristic of large supporting force of the rigid centralizer and high elasticity of the plate springs. Thus, the invention can restrict the maximum eccentricity and maximally centralize the casing string by using the large centralizing force of the plate springs, thereby ensuring centering. Meanwhile, the integral internal fixation structure prevents the centralizing sheets from shedding, and the peculiar ski function of the cambered plate spring steel sheets can prevent the phenomena of poor casing centering degree and unqualified well cementation caused by decreased centralizer consumption since more casings can result in difficulty in descending the well in the prior well cementation engineering circle. The invention has the advantages of simple structure, reliable performance, high firmness, wear resistance and convenient operation. The invention is suitable for straight wells, and especially suitable for inclined shafts, horizontal wells and slim wells.

Description

Elastic rigid centralizer

(1) technical field

The present invention relates to the centralizer of use in the construction of drilling completion setting of casing casing and cementing, particularly a kind of combined type bullet rigid casing centralizer belongs to the downhole tool class.

(2) background technology

In the well shaft fixing technology process of all kinds of drilling engineerings such as at present domestic and international oil, natural gas, salt industry, underground heat and ore deposit, ground, usually require to keep casing centralization, the cement paste that injects when making well cementation can improve displacement efficiency, fullest totally replaces drilling fluid up hill and dale, and be evenly distributed in annular space between the casing string and the borehole wall, guarantee cementing quality.The general method that adopts is to add centralizer on casing string.

Centralizer commonly used at present has two classes, one class is the elastic type centralizer, be commonly called as spring centralizer or lantern centralizer, can cooperate preferably with borehole size, has stronger compliance, especially when facing particularity stratum undergauge or borehole wall corrosion, well collapses when spoiling hole diameter and occurring more seriously enlarging, it is fairly obvious that it sets upright effect placed in the middle or expansion stream flow-disturbing raising displacement efficiency, but when hole angle is excessive, lateral force obviously increases, especially in high angle hole and horizontal well, the effect placed in the middle of setting upright of simple elastic type centralizer just seems very limited; Another kind of is category of rigid brace type centralizer, the rigidity centralizer has the restriction of determining to the off-centre of sleeve pipe, can overcome the hypodynamic problem of elastic centralizer side direction preferably, but the restriction that often is subjected to upper strata casing inner diameter and drill bit borehole diameter owing to the maximum outside diameter of rigidity centralizer is difficult to abundant amplification, be difficult to make casing string placed in the middle to greatest extent, especially in unconsolidated formation well section and hole diameter well bigger than normal, righting strip is easy to embed the stratum or centralizer departs from the well axis together with casing string integral body, produce bigger off-centre, sealing quality for improving annular space displacement efficiency and cement sheath usually is difficult to see Expected Results; And, the rigidity centralizer does not possess elastic centralizer semielliptic spring steel disc peculiar " ski " effect, in the setting of casing process, force of sliding friction between righting strip that it is hard and stratum or upper strata sleeve pipe is huge, have a strong impact on casing safety and successfully be lowered into predetermined well depth, further creeping into operation for the bottom or completion practice brings very big difficulty.

(3) summary of the invention

The objective of the invention is to provides a kind of novel casing stabbing board for cementing operation, this new casing centralizer can remedy elasticity and rigidity centralizer deficiency separately preferably, and the advantage of this two classes centralizer is rolled into one, on the big basis of rigidity centralizer support force, assist and replenish with the big advantage of spring leaf elastic telescopic degree of spring centralizer, the effect that had both had rigidity centralizer restriction maximum eccentric, can under the powerful uprighting force effect of spring leaf, casing string be set upright to greatest extent again, guarantee placed in the middle, improve the displacement efficiency of sleeve pipe and borehole wall annular space, make cement sheath evenly be full of annular space.Simultaneously, the present invention also has elastic centralizer semielliptic spring steel disc peculiar " ski " effect, it is usually poor owing to worrying that sleeve pipe is lowered to the casing centralization degree that use amount that difficulty reduces centralizer causes to stop present casing and cementing circle, the defective phenomenon of cementing quality is guaranteed cementing quality to greatest extent.The present invention is simple in structure, and is easy to use, firm reliable.

As shown in Figure 1, the present invention mainly is made up of the rigidity righting strip (2) and the leaf spring body resistance-strengthening tablets (3) of body (1) and circumferential equally distributed several high-qualitys of body (1).Have chute on each rigidity righting strip (2).Leaf spring body resistance-strengthening tablets (3) is installed in the groove, the available lock pin of an end (4) relative fixed, and the other end is a free end, can slide in the prescribed limit vertically in groove, cooperates borehole size and uprighting force to regulate.

Rigidity righting strip external diameter of the present invention is near bit diameter, but limiting boot continues off-centre; The righting strip external surface is done the anti-eccentric wear of Wear-resistant Treatment; The leaf spring body resistance-strengthening tablets that design can be born some thousand Niu Fuzheng support forces vertically in the limited range in the sliding process, can be regulated uprighting force automatically in chute, guarantee better to set upright effect, makes sleeve pipe as much as possible placed in the middle.Simultaneously, because the effect that the arch of leaf spring steel disc has " sledge " helps guiding sleeve and is lowered to smoothly.The present invention can prevent the not circuitous resistance of eccentric wear, and interior firm reliable with deciding the monolithic elastic rigid centralizer, the body resistance-strengthening tablets that do not come off is not only applicable to straight well, is particularly suitable for the well cementation of inclined shaft, horizontal well and little gap well yet.

(4) description of drawings

Fig. 1 structural representation of the present invention.

Fig. 2 is the vertical view of Fig. 1.

The operating mode schematic diagram that Fig. 3, Fig. 4 use in cementing operation for the present invention.

As shown in Figure 4, well (5) irregular: formation mud cake or soft mudstone, gypsum-salt stratum have produced undergauge on the part sandstone well section borehole wall, and hole diameter is slightly less than bit diameter (such as the A section); The well section stratum that has is stable, and hole diameter is bit diameter size (such as the B section) just; The hole diameter of most wells section is all slightly larger than bit diameter, belongs to normal, but the well section that has is because of the stratum instability, has taken place to collapse or has formed pregnant (such as the C section) because of the salt deposit dissolving. In the actual well drilled production process, certain hole deviation all can take place in most of straight wells, in addition be the needs of exploration and development, also specialized designs a lot of inclined shafts, the high angle hole cluster well, directional well and horizontal well, the cross component force of casing string has very big impact to the stressing conditions of centralizer, wish is smoothly lower to the design well depth with sleeve pipe, centralizer will face the very complicated working environments such as friction of HTHP and irregular borehole wall solid rock, the elasticity body resistance-strengthening tablets will experience hundreds and thousands of extruding and discharge, also need keep enough big uprighting force, as seen its task of setting upright sleeve pipe (6) is very arduous, but the present invention can both tackle calmly.

(5) specific embodiment

The present invention is described in further detail below in conjunction with accompanying drawing.

1, as shown in Figure 1, the present invention mainly is made up of body (1) and circumferential equally distributed several rigidity righting strips (2) of body (1), have chute on each righting strip, leaf spring body resistance-strengthening tablets (3) is installed in the groove, it is fixed relatively together with lock pin (4) to go into the downward end of well, the other end is a free end, can slide in the limited range vertically in groove.

2, as the further improvement embodiment that invents.Body of the present invention (1) circumferentially has " inverted T-shaped " chute on equally distributed several rigidity righting strips (2), and the leaf spring body resistance-strengthening tablets (3) of the little step of end band is installed in the groove, and two ends are free end, can slide in the limited range vertically in groove.

3, as the further improvement embodiment that invents.Body of the present invention (1) the circumferentially interior leaf spring body resistance-strengthening tablets of installing (3) of equally distributed several rigidity righting strip (2) upper hopper chutes also can be bouble-bow or how arc shape except being single arc.

4, further improve embodiment again as invention.Body (1) can be divided into two sections from the centre, so so only need lock pin (4) locking is all used at the two ends of leaf spring body resistance-strengthening tablets (3), this just is equivalent to add the leaf spring body resistance-strengthening tablets of an elastic centralizer in the middle of two rigidity centralizers, fix and form a novel bullet rigidity combined type casing stabbing board in interior locking mode.

Claims

1. one kind plays the rigid casing centralizer, it is characterized in that by body (1) and circumferentially equally distributed several rigidity righting strips (2) and arc leaf spring body resistance-strengthening tablets parts such as (3) are formed.

2. elastic rigid centralizer according to claim 1 is characterized in that having chute on each righting strip, and leaf spring body resistance-strengthening tablets (3) is installed in the groove.

3. elastic rigid centralizer according to claim 1 is characterized in that the chute of opening on each righting strip can be " inverted T-shaped " groove, and the both sides, end that are installed in the interior leaf spring body resistance-strengthening tablets (3) of groove can be aided with is with little step.

4. elastic rigid centralizer according to claim 1 is characterized in that leaf spring body resistance-strengthening tablets (3) can slide in the limited range vertically in groove, reach more than tens of thousand Ns to regulate uprighting force.

5. elastic rigid centralizer according to claim 1 is characterized in that leaf spring body resistance-strengthening tablets (3) and rigidity righting strip (2) chute inner bottom part can be provided with lock pin (4) or return spring.

6. elastic rigid centralizer according to claim 1 is characterized in that leaf spring body resistance-strengthening tablets (3) and rigidity righting strip (2) all are arranged in body (1) and go up integral body of formation.Rigidity righting strip (2) external diameter is slightly less than corresponding bit diameter, and body (1) internal diameter is slightly larger than the respective sleeve external diameter, and leaf spring body resistance-strengthening tablets (3) external diameter of free state is greater than bit diameter.

7. elastic rigid centralizer according to claim 1, the end that it is characterized in that rigidity righting strip (2) has been designed has the guiding function slope.

8. elastic rigid centralizer according to claim 1 is characterized in that the external surface of rigidity righting strip (2) and leaf spring body resistance-strengthening tablets (3), can make hardened artiwear and handle.

9. elastic rigid centralizer according to claim 1 is characterized in that leaf spring body resistance-strengthening tablets (3) can be single arch, also can be two arches and multiple arch.