CN201714315U - Improved round thread air-tight seal connecting structure - Google Patents

Abstract

The utility model provides an improved round thread air-tight seal connecting structure comprising a casing with external threads at one end and a collar with internal threads, wherein the casing and the collar are screwed; the external threads of the casing are fully consistent with regular API threads; the arc radius of the tooth bottom of the internal threads of the collar is greater than that of API round threads; the arc radius of the tooth crest of the internal threads of the collar is smaller than that of the API round threads; and the tooth height of the internal threads of the collar is equal to that of the API round threads. The utility model has the effects that the sealing performance of the connecting structure is strong, the cross-sectional area of a leakage path is reduced, the air-tight seal capability is no less than the method of the API round threads and the sealant, the screwing on and off performances are excellent, the contact pressure of the local area of the threads is not overhigh through appropriate modification, and sticking does not occur for triple screwing-on and twice screwing-off. In addition, the usage is simple and convenient, the inspection, management and operation are completely identical with that of the API round threads, the complete interchangeability is realized, the cost is low, and the processing is simple and efficient.

Description

Modified round thread hermetic seal syndeton

Technical field

The utility model relates to a kind of modified round thread hermetic seal syndeton.

Background technology

Petroleum gas all occupies extremely important strategic position at world energy sources and even whole economy field, is accompanied by the fast-developing of World Economics and to the continuous increase of energy demand, the exploration and development dynamics of petroleum gas is also continuing to increase.Along with the more sophisticated of geologic structure and the continuous increase of drilling depth, add cost factor, each elephant is had higher requirement to functional performance, security reliability and the cost performance etc. of oil well pipe both at home and abroad.

In petroleum and natural gas drilling industry, the market demand of oil well pipe is very huge.Relevant statistics shows, comprises the sleeve pipe that constitutes oil gas well agent structure and oil recovery, gas production oil pipe, and the demand of whole world oil well pipe in every year is above 10,000,000 tons.

For a long time, meet gas thread (the be called for short API screw thread) oil well pipe of API (American Petroleum Institute-American Petroleum Institute (API)) standard criterion, be widely used always owing to possess skills maturation, highly versatile, be easy to advantage such as processing.But the API screw thread exists many performance deficiencies that are difficult to overcome because the structure design aspect, as: the tensile strength of API round thread is lower, gas sealing ability and anti-stick button poor-performing, easily thread gluing; Though API buttress thread tensile strength is higher, the gas sealing ability of nipple is compared with the API round thread and is decreased, though anti-stick button performance is better than the API round thread slightly, but still is not very good.

Performance deficiency based on API round thread, buttress thread existence, main oil well pipe factory has also all developed special button screw thread separately in succession and has substituted common API screw thread both at home and abroad, but mostly belong to the special buckle product of the hermetic seal that has the end shape metallic leak-proof structure, because of its structure and production technology relative complex, cost of production is higher than the API screw thread far away, and its widespread adoption in the oil field is restricted.

Because the oil-gas Layer content of exploitation is lower, the pressure of the more shallow oil gas of bottom is not too high, is not suitable for the higher special buckle product of employing expense in some zone, oil field.Its hermetic seal ability can't guarantee though the price of common API circle button is suitable, and particularly after going into the well for a long time, the thread compound of smearing in the screw thread can be dry gradually, and the oiliness ingredients from lossing is become pure solid-stately by solid-liquid mixing, and packing volume reduces greatly.Being present in the leakage path that originally blocks in the API round thread flank like this will open, and can't reach the effect of hermetic seal.Therefore Oilfield using do not smear thread compound during last button and the mode of using fluid sealant instead guarantees its gas sealing ability.But the inconvenience when this kind method has also been brought last button the and the unstability of sealing performance.

At above-mentioned situation, oilfield exploitation side is when developing the hole condition that some hydrocarbon content lower pressures are not too high, structure is not too complicated, go up the tightness that the method for detaining strengthens the circle button after adopting the API round thread to smear the CATTS101 fluid sealant, partly substitute special buckle product with this, to reduce cost of production.But there is following drawback in the method:

1. cause on the joint shackle performance to reduce, increased torque wrench moment and made to twist and connect, make and finally twist that to connect the position uncertain, possibly can't arrive design attitude.And fluid sealant solidified the back in 30 minutes and is difficult to shackle, influenced operation.

2. sealing reliability is poor, owing to satisfy seal request by fluid sealant, smears uneven or very few or leaks and smear or fluid sealant stubborn not the receiving that become dry all can be leaked.The easy layering of fluid sealant long-term storage can't be satisfied seal request after the inefficacy.

Summary of the invention

At structural deficiency in the prior art, the purpose of this utility model provides a kind of modified round thread hermetic seal syndeton, is beneficial to improve the problem of common API round thread gas sealing ability deficiency, and is easy to use, reduces cost of winning.

For achieving the above object, the technical solution adopted in the utility model provides a kind of modified round thread hermetic seal syndeton, this structure includes box cupling that an end has externally threaded sleeve pipe and have an internal thread and is screwed and forms, the external screw thread of described sleeve pipe and common API screw thread are in full accord, wherein: the arc radius at the bottom of the internal thread tooth of described box cupling is greater than the arc radius of API screw thread, the internal thread tooth top arc radius of box cupling is less than the arc radius of API screw thread, the circular arc variable quantity is consistent at the bottom of the internal thread tooth top tooth of box cupling, and the internal thread tooth depth of box cupling equates with the tooth depth of API screw thread.

The radius of the internal thread tooth top circular arc of described box cupling is 0.018 to 0.020 inch, and the radius of circular arc is 0.017 to 0.019 inch at the bottom of the internal thread tooth of box cupling.

Effect of the present utility model is to use the advantage of modified round thread hermetic seal syndeton to be:

1. sealing performance is strengthened: its hermetic seal ability is not less than the mode that the API round thread adds fluid sealant.

2. good last shackle performance: suitable index word can not cause threaded portion zone contact pressure too high, guarantees that thread gluing does not take place twice shackle of three last buttons.

3. simple and convenient: check, management, operation etc. are identical with the API round thread, realize exchanging fully.

4. low-cost: processing is simple efficient, and cost and API round thread are approaching.

Description of drawings

Fig. 1 is the flute profile schematic diagram of round thread hermetic seal syndeton of the present utility model.

A, sleeve pipe B, box cupling

Circular arc at the bottom of C, external screw thread tooth top circular arc D, the API internal thread tooth

Circular arc F, API internal thread tooth top circular arc at the bottom of the internal thread tooth of E, box cupling

Circular arc at the bottom of the internal thread tooth top circular arc H of G, box cupling, the external screw thread tooth

The specific embodiment

Reaching embodiment in conjunction with the accompanying drawings is illustrated modified round thread hermetic seal syndeton of the present utility model.

Determine to use complicated structure to reach sealing effectiveness owing to improve the use background and the service condition of joint, must on the basis of API round thread, improve, reached the effect of hermetic seal by the most direct the simplest way.Button-type after the improvement is farthest approaching with the common round thread of API at aspects such as processing, check, uses, reduces production costs to make things convenient for the oil field to use.This joint is made up of sleeve pipe and box cupling two parts, and described sleeve pipe is at both sides pipe end external process male end round thread, and described collar segments connects between two sleeve pipes, both sides symmetrical configuration, the inner processing female end round thread on both sides.

Modified round thread hermetic seal syndeton of the present utility model includes box cupling that an end has externally threaded sleeve pipe and have an internal thread and is screwed and forms, the external screw thread of described sleeve pipe and common API screw thread are in full accord, arc radius at the bottom of the internal thread tooth of described box cupling is greater than the arc radius of API round thread, the internal thread tooth top arc radius of box cupling is less than the arc radius of API round thread, and the internal thread tooth depth of box cupling equates with the tooth depth of API round thread.The radius of the internal thread tooth top circular arc of described box cupling is 0.018 to 0.020 inch, and the radius of circular arc is 0.017 to 0.019 inch at the bottom of the internal thread tooth of box cupling.

The circular arc variable quantity must be consistent at the bottom of the internal thread tooth top tooth of box cupling, can not change to guarantee the tooth depth of improving the back internal thread.

As shown in Figure 1, this modified hermetic seal round thread joint design comprises sleeve A and box cupling B two parts composition, and circular arc H and API round thread regulation are consistent at the bottom of the external screw thread tooth top circular arc C of described sleeve A part and the external screw thread tooth; At the bottom of the tooth of the internal thread of described box cupling B part circular arc by the API internal thread tooth of original API round thread at the bottom of circular arc D to increase be circular arc E at the bottom of the internal thread tooth of box cupling, the tooth top circular arc is reduced into the internal thread tooth top circular arc G of box cupling by original API internal thread tooth top circular arc F.

For common API round thread joint, be empty gap of opening at the bottom of the external screw thread tooth top circular arc C of sleeve A part and the API internal thread tooth between the circular arc D, formed the leakage path of a screw type for whole joint.Leakage path area at the bottom of the tooth of the round thread tooth top circular arc C of the sleeve A part after the improvement and the round thread of box cupling B part between the circular arc E reduces greatly.Computational methods according to leakage rate:

When having the gap between two donuts and not having sealing filler, the annulus can be calculated by following formula because of the leakage rate that pressure differential produces

Q＝(πdδ3ΔP)/(12ηL)

In the formula: Q-leakage rate (m3/s) d-sealed diameter (m) δ-slit amount (m)

Δ P-pressure differential (Pa) η-dynamic viscosity (Pas) L-gap length (m)

Result of calculation is as follows: the leakage rate of improving the back joint only is about the 10%-20% of API round thread joint, and sealability improves more than 80%, considers the solid particle plugging action of dope, might realize 100% hermetic seal ability.

Because the variation of the female end screw thread circular arc of box cupling B part, original processing tool can't re-use, and needs by the tailor-made female end car silk cutter of change design.Because one on circular arc dwindles an increase at the bottom of the female end tooth top of box cupling B part and the tooth, and the variable quantity unanimity, so whole tooth depth remains unchanged, detection method after the completion of processing and API are common, and round thread is consistent.

Improve the back except that car silk cutter for same needs again tailor-made the differentiation, the processing of all the other screw threads, check, operation are all consistent with the common round thread button of common API, to reach maximum interchangeability and property easy to use.

Claims (2)

1. modified round thread hermetic seal syndeton, this structure include box cupling that an end has externally threaded sleeve pipe and have an internal thread and are screwed and form, and the external screw thread of described sleeve pipe and common API round thread are in full accord, it is characterized in that:

Arc radius at the bottom of the internal thread tooth of described box cupling is greater than the arc radius of API round thread, the internal thread tooth top arc radius of box cupling is less than the arc radius of API round thread, the circular arc variable quantity is consistent at the bottom of the internal thread tooth top tooth of box cupling, and the internal thread tooth depth of box cupling equates with the tooth depth of API round thread.

2. modified round thread hermetic seal syndeton according to claim 1, it is characterized in that: the radius of the internal thread tooth top circular arc of described box cupling is 0.018 to 0.020 inch, and the radius of circular arc is 0.017 to 0.019 inch at the bottom of the internal thread tooth of box cupling.

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