DE3241797A1 - FIBER REINFORCED PLASTIC DRILL RODS AND METHOD FOR PRODUCING THE SAME - Google Patents

Description

Fiber reinforced plastic drill pipe and method of making the same

The invention relates to a fiber-reinforced plastic drill pipe and a method for its manufacture according to preambles 1, 6 and 7. The invention is seen in that the threads at each end of the drill pipe are designed for increased stress and the fibers are arranged continuously through the apex of the thread are.

Fiber reinforced drill pipes have been in production for some time, but are because of the limitations with existing ones Products not generally used in the petroleum industry been used. Attempts to manufacture fiber-reinforced drill rods with integrated internal and external threads and equal strength as the linkage body have not been successful. Furthermore, it is not practical in a fiberglass-laminated plastic drill pipe or in other types of fiber-reinforced drill rods to cut threads because of the reinforcement during manufacture Strands are cut and the structure is weakened to such an extent that the threads break in use and are therefore worthless as a clutch.

To overcome this problem, plastic rods with metal couplings firmly attached at each end have been created been. This technique has not been universally successful. That was due to the lack of uniformity, the low level of reliability and the higher manufacturing costs.

ORIGINAL

Also, the metal parts can only be attached to the on the surface of the Linkage lying fibers are attached, which outside of the main force flow absorbing fiber bundle in the linkage lie. In addition, with a fiber-reinforced plastic, the high proportion of friction causes the problem of loosening a metallic connection with low frictional engagement avoided during use. The metal screw connections attached to the rod also cause the linkage to be heavier and more susceptible to corrosion.

Object of the present invention, it is ₉ to overcome these difficulties and to provide a uniform glass fiber reinforced plastic drill string, which is equally configured in the threads as in the main body of the rod. The drill pipe according to the invention is also characterized by low weight and corrosion resistance and a structure that is not susceptible to early failure due to scratching or roughening of the surface.

The solution to these problems is characterized in claims 1-8. An essential feature of the drill string in this invention is a method of molding and shaping one equipped with external thread and internal thread end parts A string in which a preselected amount of fibers is appropriately distributed within the complete drill string will.

Furthermore, it is a feature of the present invention to provide a Method for forming a drill pipe from plastic material to be provided, namely, by placing the fibers in the vertices the threaded ends are arranged in a load-bearing manner.

BATH ORIGINAL

Another object of the invention is to provide an improved, fiber-reinforced plastic drill pipe to be provided in which the threaded end parts have substantially the same strength as the linkage body.

Another aspect of the invention is the high Transport costs of metal rods on special pallets must be transported with spacers to avoid. The improved fiber reinforced linkage of this invention can be packaged in a strapped bundle at normal shipping costs be transported.

The main goals and benefits as well as others and specified features of this invention are intended with reference to FIG the accompanying description and claims should be understood in conjunction with the drawings.

The invention is illustrated using the following figures:

Figure 1 shows a front view of the plastic drill string in its external design and the arrangement the reinforcing fibers by means of dash-dotted lines.

FIGS. 2, 3 and 4 are cross-sectional views according to FIGS Section lines 2-2; 3-3 and 4-4 of Figure 1 showing the preferred location of the reinforcing fibers in the represent finished drill rods.

Figure 5 is a schematic view showing a trough and strands of fiber drawn through it, as Measure for wrapping the strands with liquid, hardenable plastic.

BATH

Figure 6 is the top view of the lower part of a split hollow mold for the design of the drill string, the mold having a cavity which defines the external shape of the finished drill pipe and which also shows the position of the covered fiber strands in the cavity of the lower mold part.

Figure 7 is an enlarged cross-sectional view of an end portion of the split cavity mold with the upper parts joined together. and lower part and the arrangement of the strands within the associated molding, wherein the External threads are to be formed.

FIG. 8 shows the front view of a divided hollow mold with the joined upper and lower parts and the mold cavity, shown with dash-dotted lines Lines, and the bulging tools that are used to introduce the mold ends and determine the position of the reinforcing fibers are provided in the apex areas of the external and internal threads.

Figure 9 depicts the exterior view of a mold inclusive the flowing through the same with a heated liquid to the thermosetting plastic cure within the mold.

FIG. 10 shows the lower part of the mold, with the upper part of the mold already has been removed, and the completed drill pipe.

With reference to the drawings, and doing so primarily to Figures 1-4, is the improved one according to the invention Resin drill pipe shown. The drill string TO has

BATH ORIGINAL

an external design comparable to drill rods that in the past for use in the petroleum industry were manufactured. A characteristic of drill rods is the length dimension of 7.62 m (25 feet), with a maximum Outside diameter in the coupling zone of 3.81 cm (1 1/2 inches) Or less. The drill pipes are used to pump movements from a pumping unit on the surface of the earth to a Transfer pump to the drilling floor. In this way, the drill rods are moved up and down a pipe. Around a column of liquid to lift from the bottom of a borehole to the surface of the earth and to pump the liquid to the surface, drill rods have to withstand considerable tensile loads. The most common drill pipe in industry today is made of steel or steel alloys. However, these are subject to corrosion, and among many Borehole conditions have a relative proportion of the drill string short lifetime. To counteract this, manufacturers have made metal 1-alloyed drill rods, which are less susceptible against corrosion are brought on the market, but alloy drill pipes are prohibitively expensive.

The present invention provides a drill string which is substantially impervious to corrosion and the other Advantages over steel or other metal 1-alloyed drill rods Has.

The linkage 10 includes a long, cylindrical stretched one Base part 12. At one end there is a pin or male end 14 and at the other end is a receiving or 16 female end attached. In this manner of construction (which is typical of the construction of some types of drill pipe is made of steel) the linkage to the exclusion of

BATH

separate couplings are screwed together. In the past, steel drill pipes have been made in this manner; however, recently the known steel drill pipes have male threads at each end with a separate female coupling for connecting the pipes together. These advantages of the linkage of the type shown in Figure 1 are _a that no separate coupling devices are required.

The male end H generally includes an enlarged head portion 18 with a planar, annular surface 18A ₉ that is perpendicular to the longitudinal axis of the linkage. The head part 18 has key areas 20, as shown in FIG. These allow tools to be attached »to connect the end of the rod so that it can be attached to an adjoining rod.

The head part 18 is adjoined by a male part 22 with a thread on its outer surface. The female end 16 has an enlarged outer diameter area 24. It also includes a set of oppositely disposed bowl surfaces 28 on opposite sides of the enlarged cylindrical portion 24. In the interior of the cylindrical part 24 there is an internal thread 30 ₅ , which is arranged to receive the external thread of a subsequent length unit of a drill rod. The end surface 24A is annular and in a plane perpendicular to the longitudinal axis of the drill pipe. When a male, externally threaded end of the next adjoining drill pipe is screwed into the receiving end 16, the male., Annular surface 18A abuts firmly with the female, annular surface 24A, so that it is ensured that none

BATH ORIGINAL

There is "play" in the screw connection that connects one linkage to the other.

The drill pipe, as described so far, is not unlike the previously known drill pipe made of metal. An important and The distinguishing feature of the drill string in this invention, however, is that it is formed of non-metallic material, i.e. plastic material, and most importantly that it is with increased strength due to the equipment with lengthways arranged, flexible and reinforcing fiber strands 32, as indicated in the dash-dotted lines in FIGS. 1-4. The fiber strands 32 are preferred arranged in the full length of the drill string and of the utmost importance to the invention is the arrangement of the Fiber strands 32, in such a way that they extend over the subsequent peripheral surface of the external thread 22 and the internal thread 30 extend further. In particular, the fiber strands 32 extend into the apex of the thread that the External thread part 22 and the internal thread part 30 form. In Are the fibers in a sequential arrangement of threads of this kind? so united that they have the same strengths with respect to the linkage body. In the past, as shown above, Try to make plastic drill pipes, not particularly has been successful, as the most common technique is to attach threaded metal ends to a tensile, extruded, to attach fiberglass-reinforced drill rods. Even if a large amount of fiber-reinforcing strands are in the bandage were used in the drill pipe, the problem of full traction transmission has remained unsolved to this day.

As shown in Figures 2-4, the fiber reinforcement Strands 32 in the logs! Part 22A of the external thread and

arranged in the apex parts 30A of the internal thread. The fiber strands are thus concentrated on the connection in the peripheral surface of the drill pipe, at least in the parts which form the male end 14 and the female end 16. If necessary, provision can be made for additional fiber strands to be arranged in the inner parts of the drill string _9, even if such are not shown in the drawings.

The gist of this invention, however, is not simply that Thought of including reinforcing strands in the Plastic drill pipe, rather, it is the inclusion of the same in a manner that increases the tensile strength of the drill pipe due to the arrangement of the strings continuously in the male and female thread parts of the drill rod significantly enlarged.

Referring now to Figures 5-10, there is shown a method of making improved drill pipes in accordance with this invention described. The first step is to wrap a bundle of fiber strands with thermosetting plastic as shown in FIG. A pan 34 contains a quantity of catalyzed, liquid, thermosetting plastic 36. The use of rollers 38 allows a bundle of reinforcing, flexible fiber strands 32 to pass through the liquid 38 are drawn so that the strands are completely interspersed with thermosetting plastic.

FIG. 6 shows the lower part of a split hollow mold for the purpose of shaping a drill rod according to the invention. The upper part has essentially the same appearance on _s and if the parts of the mold are assembled, is obtained

LAD ORSGiMAL

a hollow shape that gives the outer surface of a complete drill pipe. The Forniuntertei 1 42 is open and a Strand bundle 32 is inserted into it. The mold part 44 is then placed on the lower part of the mold, as shown in Figure 8, the strands 32 being held under slight tension. As shown in FIG. 7, the glass fibers become overhanging in the shape of a bell arranged. Thereafter, a male bulging tool 46 is formed into the mold ends defined by parts 42 and 44 are introduced. The design of the male bulging tool is such that it adapts to the part of the hollow form that has the external thread on the complete Forms drill pipe.

The bulging tool 46 is used to spread the fibers so that they are adjacent to the surface of the cavity are arranged. The fibers, saturated with liquid, thermosetting plastic, keep their position, adjacent to them the peripheral surface of the hollow mold at and the bulging tool 46 is held in this position for so long until the thermosetting plastic is crosslinked and cured into a stable shape. After curing, the male becomes Bulging tool moved back, and the cavity created by the Mold is either clogged or castable resin is used to fill the cavity.

In the same way, a female bulging tool is made 4fl inserted into the open end of the mold to seal it against the inner part of the internally threaded configuration at the receiving end of the drill string to adapt. The female bulging tool 48 also serves the purpose of spreading the fiber strands, so that the strands spread out within the areas which form the apex of the internal thread. Additional

U- £ j OrtIGlNAL

Plastic is added to the mold, pressure is applied and heated liquid is flowed in through the tube 40, as shown in FIG.

After the plastic has hardened in the mold, the mold parts are separated and the finished drill pipe is made taken out. The insert that forms the internal thread 30 is also removed. Such is the drill pipe Cast with its external and internal thread, without a mechanical process is required for production. In this way the reinforcing fibers remain undamaged, so that they have the full tensile force over the entire length of the linkage, including the critical thread areas. In order to additionally strengthen the housing or the female end ^ the cylindrical part 24 can be used for receiving radial stress are enveloped.

The reinforcing fibers can be made of glass fiber, metal 1aramit, Carbon fibers, graphite fibers, carbide fibers, boron fibers or mixtures of these fibers. The thermoplastic Plastic from which the drill rods are formed and the Plastic in which the fibers are used as a process step in the Manufacture of the linkage can be saturated, epoxy-polyester, Vinyl ester resin or the like. The temperature and pressure that the resin assemblies experience during curing are exposed to depend on the type of plastic, which is based on experience in the manufacture of such thermoplastics are known.

The finished drill pipe has significant advantages over this the known state of the art in the production of drill rods and in particular has a considerably improved Power transmission in the male and female thread parts

BATH ORIGINAL.

and complete corrosion protection against all liquids » which are found in the oil drilling production area. The problem of electrolysis is also ruled out.

The invention thus discloses an improved drill pipe that is formed from plastic material and that in plastic having reinforcing fiber strands, the drill string having an externally threaded pin end portion at one end and at the the other end has an internally threaded housing end part, and the Fibers are held adjacent the outer surfaces of the pin and housing end portions, the fibers in the pin end themselves within the enlarged outside diameter billet part of the external thread and the fibers in the housing end part are inside of the reduced inner diameter thread. The invention also discloses a method of making a fiber reinforced plastic drill pipe using use a split hollow mold taking into account the operations of the Arrangement of several flexible, reinforcing fibers in the mold, the mold having a cavity that has the external dimensions of the completed drill pipe determined, having and the Strands are held in close proximity to the mold wall. An additional plastic mixture is added to the mold, this hardening in the mold; the mold is divided to demould the formed drill pipe.

BATH ORIGINAL

Claims (8)

PATENT CLAIMS A method for producing a fiber-reinforced plastic drill pipe with a threaded part at each end using a mold, characterized in that a plurality of flexible, reinforcing fiber strands pre-soaked with plastic are inserted into one half of a divided hollow mold, the closed mold having a cavity which determines the outer shape of the finished drill string and that the strands are held close to the mold wall, in particular in the areas of the threaded end parts, while an additional plastic mixture is added to the mold so that the mold is closed and that Plastic material hardens within the mold and that the mold is divided in order to remove the formwork from the drill pipe. 2. The method of claim 1, characterized qekennzeichnet _s that the operation of holding the Stränne close to the mold wall BATH ORIGINAL Bavarian Voroinsbanl; Munich, account no. 332495 (BLE 70020270) - German receipt! -. Münchsn, account no. 32/08050 (BLZ 70070010) Post office in Munich. Account number tß33fl7. Sioo in the 7w.nmi « includes the operation of inserting a bulging tool into the ends of the mold to wrap the fiber strands through the Mold pressure to match the design of the threaded to displace provided end parts to the outside. 3. The method according to claim 1, characterized in that the operation of curing the plastic material includes the application of steam within the mold for rapid heat transfer which is then cured by rapid cooling of the form by means of water for the purpose of quick demoulding and handling of said drill rod follows. 4. The method according to claim 1, characterized in that said strands held close to the mold wall are under tension stand. 5. The method according to claim 1, characterized in that the process of curing the plastic material within the form includes the application of heat and pressure in the appropriate order. 6. Process for the production of a fiber-reinforced plastic drill pipe having an externally threaded spigot end portion at one end and an internally threaded Housing end part at the opposite end using a mold provided with a lower part and an upper part, the cavities when the mold is joined together exert pressure on the outer shape of the drill pipe, characterized in that the flexible, reinforcing Fibers are encased with liquid, thermosetting plastic that the encased fiber strands in the cavity of a lower mold part are inserted, with additional plastic mixture being added and that the upper and lower parts of the mold are closed, during which the fiber strands then adjoin the wall of the cavity shape of the pin end and receiving end parts be held that bulging tools are inserted into each end of the mold to urge the strands outwardly into the mold cavity and the threading of the threaded portions to form in the mold and that the plastic material has hardened inside the mold and that the mold can be removed of the formed drill pipe is divided. 7 «Fiber-reinforced plastic drill pipe, which has a large number of reinforcing fiber strands, characterized in that the fiber strands (32) in the threaded parts (22 _S 30) are arranged continuously and generally in the planes along the longitudinal axis of the drill pipe and that all fiber strands ( 32) extend into the thread design and its apex parts (22A, 30A). 8. Fiber-reinforced plastic drill pipe according to claim 7, characterized in that there is a threaded pin end part (14) at one end and a threaded housing end part (16) at the other Has the end and that the fiber strands (32) extend into the enlarged outer diameter and the reduced inner diameter of the parts forming the thread extend.