FIELD

The present description relates to the field of providing a pressure pulse in a pipe line. In particular, the present description relates to a fluid pulse apparatus for use in down hole drilling.

BACKGROUND

The present description specifically discusses generation of a fluid pulse in a down hole drill string. However, it will be appreciated that the concept described herein may be applicable to any fluid line where it is desirable to create a fluid pulse and no limitation is intended thereby.

In the oil and gas exploration and extraction industries, a drill string is lowered into a bore. In such operations a drilling fluid known as "mud" is pumped from the surface through the drill string to exit from nozzles at the drill bit. The mud assists in dislodging and clearing material from the cutting face and carries the dislodged material through the drill bore to the surface.

It is well known in the industry that providing a pulsed fluid flow that can create a percussive or hammer effect can improve the drilling rate. The pulse of fluid flow is generated by periodically restricting the fluid flow so as to create a pressure difference. There are many different methods that have been proposed so as to restrict fluid flow. One principle is to provide turbines, rotors or other means that can be driven by the fluid to operate a valve that can restrict flow. Such valves have an axially reciprocating poppet or piston that can cooperate with a narrowed bore so as to control fluid flow. The reciprocating movement is operated by a cam assembly that is driven by the rotating turbine.

Two examples of such a valve arrangement are provided in US 4830122. In the first example, a cam follower or followers are fixed to the upstream end of a turbine for rotation. The follower(s) is operatively associated with a cam that is fixed against rotation. A piston or valve member is mounted to the piston. The action of the cam follower(s) upon the cam causes cyclical reciprocating movement of the cam and attached piston.

US 4830122 also describes an alternate embodiment in which the cam and follower assembly are at the downstream end of the turbine. The cam is fixed against rotation such the cam action that occurs upon rotation of the turbine causes the entire turbine to reciprocate axially. The piston valve member is mounted to the upstream end of the turbine for cooperation with an annular valve ring.

US 4830122 also teaches that the percussive effect caused by the pulsing action of the fluid can be further enhanced by connecting the pulse apparatus to a shock tool. A shock tool is a pressure responsive device that expands and contracts in response to varying fluid pressure. Shock tools are conventionally used to isolate the drill string from axial deflections produced by the bit during drilling operations. However, when a shock tool is operatively engaged with a fluid pulse apparatus the expansion and contraction of the shock tool can provide a percussive effect at the drill bit.

Since US 4830122 has been published, there have been a number of different types of fluid pulse apparatus proposed for use with or without a shock tool. Such further fluid pulse tools have arrangements including rotating plates with axial flow openings that can open and close as a rotor is driven by the fluid.

US 6,279,670 describes a downhole fluid flow pulsing apparatus having a valve member driven by a fluid actuated positive displacement motor to provide a varying fluid flow and a shock tool responsive to the varying fluid flow. Positive displacement motors have a power section comprised of a stator and a rotor. The stator consists of a steel tube that contains a bonded elastomer insert with a lobed, helical pattern bore through the centre. The rotor is a lobed helical steel rod. When the rotor is installed in the stator, the combination of the helical shapes and lobes form sealed cavities between the two components. When drilling fluid is forced though the power section the pressure drop across the cavities will cause the rotor to turn inside the stator. The valve that is operated by the positive displacement motor has a stationary valve plate and a valve plate that is rotated by the motor. The valves each have slots that move in and out of alignment during rotation of the rotatable plate, thereby creating a variable fluid flow.

While many of the fluid flow pulse devices described in the prior art have proven to be effective at increasing drilling penetration rates they have a number of disadvantages which has prevented their widespread adoption. It is well known and appreciated in the drilling industry that it is difficult to design down hole tools which will operate reliably under the constantly changing properties of drilling mud and the constantly increasing hydrostatic pressure at downhole locations. This problem is exacerbated by the small space within which downhole tools must fit. In many drilling situations the downhole tools have an outside diameter of only 4¾ inches. These dimensional restraints impose onerous constraints on the design of such tools.

Further, many down hole tools have polymeric seals or elastomers. Such materials are subject to wear, abrasion by particles in the drilling fluid and can only be operated within certain temperature ranges and cannot be used with non-aqueous chemicals.

Despite the numerous prior art arrangements, there is constant desire in the oil and gas industry to provide fluid pulse apparatus that are cost effective to manufacture whilst being sufficiently robust to withstand the significant adverse operating conditions with minimal maintenance and associated down time. It will be appreciated that drill string downtime can have significant economic disadvantages.

It is therefore an object of the present disclosure to provide an alternative fluid pulse apparatus. SUMMARY

According to one aspect, there is disclosed a fluid pulse apparatus adapted to be connected to a pipe line, the apparatus comprising; a housing defining a fluid flow passage for a flow of fluid from an upstream end towards a downstream end; a turbine assembly within the fluid flow passage, the turbine assembly having an upstream annular cam follower and a downstream annular cam follower; at least one turbine member that is operatively connected to the upstream annular cam follower and the downstream annular cam follower and that is actuated by a flow of drilling fluid in the fluid flow passage so as to cause rotation turbine assembly; a piston fixed to the upstream annular cam follower or the downstream annular cam follower; the fluid flow passage has a narrowed fluid flow passage section located upstream of the turbine assembly when the piston is fixed to the upstream turbine surface such that the piston is receivable within the narrowed fluid flow passage or the narrowed fluid flow passage is located downstream of the turbine assembly when the piston is fixed to the upstream annular turbine such that the piston is receivable within the narrowed fluid flow passage; at least one upstream cam surface fixed to the housing for cooperation with the upstream annular cam follower and at least one downstream cam surface fixed to the housing for cooperation with the downstream annular cam follower; such that when the turbine assembly including the turbine sleeve is caused to rotate, there is a cam action between the upstream follower(s) and the upstream annular cam surface and between the downstream cam follower(s) and the downstream annular cam surface that causes the turbine assembly to reciprocate axially within the fluid flow passage such that the piston moves between a flow restricting position within the narrowed fluid flow passage and an open position to effect periodic flow restriction of the flow of fluid through the fluid flow passage.

The apparatus may be adapted for connection to any suitable pipe line. Suitably, the apparatus is for connection to a drill string for downhole drilling.

The fluid flow passage has a narrowed fluid flow passage section. The narrowed fluid flow passage section is suitably in the form of a plate with an aperture or orifice.

Suitably the narrowed fluid flow passage defines a venturi. The narrowed fluid flow passage section can be either upstream or downstream of the turbine assembly. As the piston is receivable within the narrowed fluid flow passage, it follows that if the narrowed fluid flow passage is at the upstream end, the piston is fixed to the upstream turbine and vice versa.

Suitably, the piston is fixed to upstream turbine surface which means that the piston moves upwards towards the flow restricting position and downwards towards the open position. In this case, if any debris or other particles in the fluid becomes jammed between the piston and the narrowed fluid flow passage section, the piston may be forced downwards into the open position due to the reduced flow to the turbine assembly and the downward hydraulic force on the piston. The forced downward movement of the piston would allow for the debris to clear so as the apparatus may continue to function. On the other hand, if the piston is fixed to the downstream turbine surface the piston moves downwards towards the fluid flow restricting position and upwards towards the open position. In this case, if there is any debris or other particles in the fluid, the piston may become jammed in the flow restricting position due to debris becoming caught between the piston and the narrowed fluid flow passage section. Unlike the situation above, the downward forces continue to force the piston into the jammed position instead of towards the open position. Such jamming may stop the tool from functioning.

Further, when the piston is fixed to the upstream turbine surface the fluid flow into the turbine assembly is controlled. When the piston is fixed to the downstream turbine surface the fluid flow out of the turbine assembly is controlled. Flow control into the turbine assembly may be advantageous as this may alleviate pressure build up within the turbine assembly and exposes the turbine member to less adverse forces.

Alternatively, the piston may be tapered across itself so as to provide a restrictive fluid flow passage on one side of the piston and an unrestricted flow passage on the opposite side of the piston. Further, the fluid flow passage can have an extension of the opening of the fluid flow passage within its wall. The inventor has found a new and novel way of aligning the piston fluid flow passage and the fluid extension opening of the fluid flow passage so that a very effective closed position is achieved when the cam follower is in the high point position of the cam. Once the cam follower rotates around to the low point position of the cam, the piston fluid flow passage will rotate 180° and axially be lifted so that the piston fluid passage and the fluid flow passage opening are completely miss aligned. Rotating the piston around an additional 180° will return the piston to the aligned open position. The benefits of timing the movement of the piston and the fluid flow passage with the cam profiles, allows for a cleaner, more defined and hydraulically adjustable pulse. Suitably, the relative outside diameter of the protruding narrowed fluid flow passage and the internal diameter of the turbine sleeve are such that the protruding narrowed fluid flow passage remains within the internal diameter of the turbine sleeve. Flow passes into the turbine sleeve which in turn restricts fluid flow to the outside diameter of the turbine sleeve. Suitably, the relative dimensions of the piston and the narrowed fluid flow passage are such that the piston cannot fully close the narrowed fluid flow passage section. A complete closure of the fluid flow may cause the turbine assembly to stall.

Suitably where the narrowed fluid flow passage section includes a plate or valve ring, the plate or valve ring are adapted for easy removal and replacement with a plate or valve ring with an orifice of a different size. In this way, the dimensions of the narrowed fluid flow passage section may be tuned for different conditions such as fluid weight and viscosity. In addition to, or alternatively, the piston may be adapted for replacement with a piston of different dimensions.

The apparatus has a turbine assembly that includes at least one turbine member. The at least one turbine member may be any suitable configuration, known in the turbine arts, such as a screw, rotor or the like that can be caused to rotate axially in response to fluid flow. The at least one turbine member is actuated by the flow of drilling fluid through the fluid flow passage.

Suitably the at least one turbine member is a screw such as an Archimedes screw. The turbine member is operatively connected to the turbine sleeve and the upstream annular cam follower and the downstream annular cam follower such that the respective annular cam followers rotate with rotation of the turbine assembly. Such operative connection may be by any suitable means.

Suitably, outer edges of the turbine member(s) are fixed to a turbine sleeve such that the sleeve rotates with the turbine member(s). Such an arrangement is known in the turbine arts. An advantage of having the turbine members fixed to the sleeve is that the sleeve ends can define the annular cam followers which can avoid or limit the need for seals, bearings, locating shafts and the like. Suitably where the turbine assembly includes a turbine sleeve, the turbine assembly does not include a central shaft. Alternatively, the turbine member(s) may be fixed to a shaft and the respective cam followers may be fixed to the ends of the shaft.

The present inventor's use of rotating cam followers mounted onto the turbine sleeve acting on fixed cam surfaces is new and novel to the arrangement described in US 4830122 in which the cams are fixed against rotation and the followers comprising a pair of diametrically opposed Finger means attached to the turbine rotate.

The present inventor's use of rotating cam followers mounted onto the turbine sleeve acting on fixed cam surfaces is new and novel to the arrangement described in US 4830122 in which the cams are fixed against rotation and the follower comprises a single finger secured to said turbine means and engaging the annular cam at a point located outwardly of the axis of rotation.

Upstream and downstream cam surfaces are fixed to the housing for cooperation with the respective upstream and downstream cam followers. Suitably, the cam followers are designed so as to apply a symmetrical force to each cam surface.

In addition to, or alternatively, the cam surface may be adapted for replacement with a cam surface of different dimensions.

As the cam surface are fixed in place and the cam follower's rotate, the cam action between the rotating cam followers and fixed cam causes reciprocating axial movement to be transferred to the entire turbine assembly causing the turbine assembly to reciprocate axially. A pulse generating arrangement described in US 4830122 also employs axial movement of the turbine assembly. However, this is achieved using a downstream rotating follower finger attached to a turbine, operating against a fixed cam. The upwards motion of the turbine is positively caused by the contact between the cam and follower finger and the return movement is as a result of gravity. This can generate undesirable shock and instability. It will be appreciated that these forces can be considerable under normal drilling operations in which fluid flow rate can vary significantly for example between 60 gallons per minute and 140 gallons per minute, the pressure may be between 4 psi and 1 190 psi and the flow restriction may operate between open and flow restricted positions between about 1 and 3 pulses per second. It will be appreciated that for some applications, the fluid flow rate, pressure and/or periodic restriction cycles can fall outside these ranges.

However, the present inventor has surprisingly and unexpectedly discovered that such axial instability can be at least partially ameliorated by providing a turbine assembly with an upstream annular cam follower at the upstream turbine assembly end fixed to the turbine sleeve in combination with a downstream annular cam follower at the downstream end of the turbine assembly fixed to the turbine sleeve. The cam action of the upstream annular cam follower assembly and upstream fixed cam positively returns the turbine assembly to the lowest position rather than relying on gravity. The interaction between the upstream and downstream cams and cam followers fixed to the turbine sleeve provides a very smooth reciprocating movement of the turbine assembly in which the turbine assembly is always subject to a positive axial force in both directions.

Such smooth reciprocating movement reduces or minimises lateral vibration. Lateral vibration can cause damage to other components within the tool itself or other components within the drill string.

The cam profiles can be designed so as to provide one or more pulses for each revolution of the turbine assembly.

The apparatus may be used in a drill string conjunction with a pressure pulse responsive device such as a shock tool that can expand or contract in response to the fluid pressure variation to create axial movement of the drill string.

According to a further aspect, there is described an assembly for delivering a percussive effect in a down hole drill string; the assembly including a fluid pulse apparatus as described in the first aspect and a fluid actuated pressure pulse response device that is actuated in response to the fluid pulse generated by the fluid pulse apparatus.

The pressure pulse apparatus may be placed either upstream or downstream of the fluid pulse apparatus.

According to a further aspect of the invention, there is provided a method of drilling comprising operatively connecting a fluid pulse apparatus as described in the first aspect to a drill string and operating said drill string in a down hole mode. The present invention provides a fluid pulse apparatus for down hole drilling, comprising; a housing defining a fluid flow passage for a flow of drilling fluid from an upstream end towards a downstream end; a turbine assembly within the fluid flow passage, the turbine assembly having an upstream annular cam follower and a downstream annular cam follower, at least one turbine sleeve that is operatively connected to the upstream annular cam follower and the downstream annular cam follower and is actuated by the flow of drilling fluid so as to cause rotation of the turbine assembly and a piston fixed to the upstream turbine surface; the fluid flow passage has a narrowed fluid flow passage upstream of the turbine assembly such that the piston is receivable within the narrowed fluid flow passage; at least one upstream cam surface fixed to the housing for cooperation with the upstream annular cam follower and at least one downstream cam surface fixed to the housing for cooperation with the downstream annular cam follower; such that when the turbine assembly is caused to rotate, there is a cam action between the upstream cam follower(s) and the upstream annular cam surface and between the downstream cam follower(s) and the downstream annular cam surface that causes the turbine assembly to reciprocate axially within the fluid flow passage such that the piston moves axially between a flow restricting position within the narrowed fluid flow passage and an open position to effect periodic restriction of the flow of drilling fluid through the fluid flow passage. Preferably, there is a single turbine member that is an Archimedes screw.

Preferably, the upstream and downstream cam surface can be changed with another cam surface profile.

Preferably, the turbine assembly includes a turbine sleeve and outer edges of the at least one turbine blade member(s) are fixed to the turbine sleeve.

Preferably, a symmetrical cam force is applied to the upstream annular cam surface by the at least one upstream follower and a symmetrical cam force is applied to the downstream annular cam surface by at least one downstream follower. Preferably, the narrowed fluid flow passage includes a plate with an orifice.

Preferably, the narrowed fluid flow passage includes a plate with an orifice that has an extended opening over a portion of the fluid flow passage wall.

Preferably, the plate is adapted so that it can be removed and replaced with a plate with an orifice of a different size. Preferably, the piston is adapted for replacement with a piston of different dimensions.

Preferably, the piston has a tapered head.

Preferably, the piston has a tapered head across itself so that fluid is directed to exit to the side of the piston. In another aspect, the present invention provides a fluid pulse drilling tool for downhole drilling comprising the fluid pulse apparatus of the present invention.

In another aspect, the present invention provides an assembly for delivering a percussive effect in a down hole drill string; the assembly including the fluid pulse apparatus of the present invention and a fluid actuated pressure pulse response device that is actuated in response to the fluid pulse generated by the fluid pulse apparatus. Preferably, the fluid actuated pressure pulse responsive device is located upstream of the fluid pulse apparatus.

Preferably, the fluid actuated pressure pulse responsive device is located downstream of the fluid pulse apparatus. In another aspect, the present invention provides a method of drilling comprising operatively connecting the fluid pulse apparatus of the present invention to a drill string and operating said drill string in a down hole mode.

In another aspect, the present invention provides a method of drilling comprising operatively connecting the assembly to a drill string and operating said drill string in a down hole mode.

In another aspect, the present invention provides a fluid pulse apparatus adapted to be connected to a pipe line, the apparatus comprising; a housing defining a fluid flow passage for a flow of fluid from an upstream end towards a downstream end; a turbine assembly within the fluid flow passage, the turbine assembly having an upstream annular cam follower and a downstream annular cam follower; at least one turbine member that is operatively connected to the upstream annular cam follower and the downstream annular cam follower and that is actuated by a flow of drilling fluid in the fluid flow passage so as to cause rotation turbine assembly; a piston fixed to the upstream turbine surface or the downstream turbine surface; the fluid flow passage has a narrowed fluid flow passage section located upstream of the turbine assembly when the piston is fixed to the upstream turbine surface such that the piston is receivable within the narrowed fluid flow passage or the narrowed fluid flow passage is located downstream of the turbine assembly when the piston is fixed to the downstream turbine surface such that the piston is receivable within the narrowed fluid flow passage; at least one upstream cam surface fixed to the housing for cooperation with the upstream annular cam follower and at least one downstream cam surface fixed to the housing for cooperation with the downstream annular cam follower; such that when the turbine assembly is caused to rotate, there is a cam action between the upstream follower(s) and the upstream annular cam surface and between the downstream cam follower(s) and the downstream annular cam surface that causes the turbine assembly to reciprocate axially within the fluid flow passage such that the piston moves between a flow restricting position within the narrowed fluid flow passage and an open position to effect periodic flow restriction of the flow of fluid through the fluid flow.

Preferably, according to the assembly, a piston is tapered across itself so as to provide a restrictive fluid flow passage on one side of the piston and an unrestricted flow passage on the opposite side of the piston; the fluid flow passage has an extension of the opening of the fluid flow passage within its wall; the piston fluid flow passage and the fluid extension opening of the fluid flow passage are aligned so that a closed position is achieved when the cam follower is in the high point position of the cam; wherein as the cam follower rotates around to the low point position of the cam, the piston fluid flow passage will rotate 180° and axially be lifted so that the piston fluid passage and the fluid flow passage opening are completely mis- aligned; and the piston rotates around an additional 180° enabling the piston to return to the aligned open position. BRIEF DESCRIPTION OF THE FIGURES

Figure 1 is a schematic view of the lower end of a drill string; Figure 2 is a schematic cross sectional view of an apparatus of one aspect;

Figure 3 is a schematic cross section of the upper section of the aspect shown in figure 2;

Figure 4 is a schematic cross section of the lower section of the aspect shown in figure 2 Figure 5a is a schematic of the piston in the closed position;

Figure 5b is a schematic view of the piston in the open position;

Figure 6 is a schematic cross sectional view of an apparatus of a further aspect; shown in figure 2;

Figure 7 is a graph showing pulse pressure as a function of time as generated by an apparatus of the present disclosure and

Figure 8 is a further graph showing pulse pressure as a function of time generated by an alternate configuration of an apparatus of the present disclosure.

Figure 9a is a schematic of the piston fluid flow passage in the open position; Figure 9b is a schematic of the piston fluid flow passage in the closed position. Figure 10 is a schematic of the cam profile high position and low position.

DETAILED DESCRIPTION OF THE FIGURES Figure 1 is a schematic view of the lower end of a drill string 8 that includes a fluid pulse apparatus 7 of the present invention. The drill string 8 includes a conventional drill string component 2 that may be a drill collar, a drill pipe, a down hole mud motor or a measurement while drilling tool or a shock tool.

Fig.1 shows the Fluid pulse apparatus connected to the drilling tubular via 1 and 6. 1 is the top of the tool where the fluid enters into the fluid pulse apparatus (upstream end). 6 is where the fluid exits the fluid pulse apparatus (downstream end).

The fluid pulse apparatus 7 comprises a housing with an upper sub 3 connected to a lower main body sub 4. The housing defines a fluid flow passage for a flow of drilling fluid from an upstream end towards a downstream end 5.

The main body sub 4 is connected to a lower drill string component 6 that can also be any conventional down hole drilling component such as that may be a drill collar, a drill pipe, a down hole mud motor, shock tool or a measurement while drilling tool but not limited to. Figure 2 shows a schematic cross section of the fluid pulse apparatus 7, with figures 3 and 4 showing details of the upper and lower sections respectively.

The upper sub 3 is connected to the lower main sub 4 through threaded connection 10. The upper sub 3 has a bore 9 defining a fluid flow passage. A bore restriction or narrowed fluid flow section 1 1 is located at the downstream end of the bore 9.

An orifice plate 21 inserted into the downstream end of the connection 10 downstream of the bore restriction 1 1 .

Fig.2 illustrates a cut away of the tool. Figures 2 and 3 show that the flow from the bore restriction 1 1 through the orifice 21 a of the orifice plate 21 is restricted by the head 12 of a piston 13. The piston 13 is moveable between an open position (shown in detail in Fig. 5b) in which there is no fluid flow restriction through the bore restriction 1 1 and a fluid restricting position (shown in detail in Fig. 5a). As can be seen in Fig. 5a, the fluid flow is not restricted completely as this will cause the turbine to stall, as will be discussed further below.

Figures 5a and Fig.5b show a close up view of Fig.3. The piston (13) travels up and down into the orifice (1 1 ) and then back out which causes a tight restriction of the fluid passage in the up position and then a loose open restriction when the piston goes back down. In turn, the fluid will have high pressure in the up position and low pressure in the down position. By adjusting the internal diameter of the orifice 1 1 and the outside diameter of the piston 13, the fluid pressure (pressure pulse) can be manipulated to be higher or lower. This is shown in Figures 7 and 8 wherein pressure is measured in PSI.

The orifice plate 21 can be readily replaced with a plate having a different sized orifice. In this way, the apparatus can be adapted for different flow rates, fluid types and mud types.

The head 12 of the piston 13 piston is designed to have a taper so as to reduce the downward hydraulic force exerted on the piston 12 so as to reduce the torque required for rotation of the turbine.

The main body sub 4 has a radial bushing 20 pressed into the inner diameter. A shaft less helical screw or Archimedes screw 16 is mounted within the main body sub 4 for rotation.

The outer edges of the screw 16 are fixed to a turbine sleeve 17. The turbine sleeve 17 is fitted into the bushing 20 with a clearance.

The upstream and downstream ends of the turbine sleeve 17 are defined by respective cam followers 14, 18.

Opposed cam profiles 15, 19; are attached to main body 4 with threaded pins 22, 23, 24, 25 through the outer walls of the main body and project inwardly into the main body 4 to lock the opposed cam profiles 15, 19.

The upper and lower cam surfaces 15, 19 are in contact with the cam followers 14, 18; and the sleeve 17 is thereby supported by the lower cam follower 18. In use the fluid flows into the main sub body 4 and causes the screw 16 to rotate as per conventional pulse tools. However, contrary to conventional tools, the present apparatus includes upper and lower cam followers that rotate with the turbine. The cam action of the rotating cam followers 17,18 on the fixed cam surfaces 15,19 causes the screw 16, piston 13 and turbine sleeve 17 to reciprocate axially and the whole turbine assembly 26 is alternatively positively pushed upwards by the lower cam action and positively pushed downwards by the upper cam action. Such positive action in both directions imparts a high degree of axial stability to the reciprocating movement. The result is an increase in reliability and tolerance to working angles, varying fluid flows and the like.

The cam profiles can be adjusted so as to adjust the overall axial movement of the piston. This could be from 1 mm movement through to 20mm movement but not limited to. This adjustment can then be used to tune the apparatus so as to achieve a fluid pulse under different conditions.

Figure 6 shows an aspect of a main sub body 4. The body 4 is similar to that describe above with respect to figures 1 to 5 in having an Archimedes screw 16 attached to a turbine sleeve 17. Upstream and downstream cam followers 14, 18 are attached to the turbine sleeve 17. In this case, the screw 16 has a shaft 27. Fig.6 shows the piston 13 attached to the turbine 17. The turbine is mounted and fixed into a sleeve 17 which is also rotating due to the turbine 17.

Figure 7 is a graph showing pulses per second at 700 psi that are created over one second by a fluid pulsing apparatus of the invention pumping 120 gallons per minute. There are 5 revolutions of the turbine apparatus per second and 5 pulses, representing one pulse per revolution.

Fig.7 and Fig.8 also show how many times the piston 13 moves in and out of the orifice 1 1 over a time frame of 1 second. The amount of pressure pulses per second can be increased or decreased by adjusting the "pitch" of the turbine. (This method is very similar to adjustment of a boat propeller). The piston goes up and down for every one completed revolution of the turbine because it is fixed to the turbine. Therefore, the piston also rotates through its up and down movement.

Figure 8 is a graph of showing pulses per second at 850 psi that are created over one second by the same fluid pulsing apparatus as that used to generate the graph of figure 7, also pumping 120 gallons per minute. There are 5 revolutions of the turbine apparatus per second and 10 pulses, representing one pulse per revolution.

The fluid pulses may be seen to be very consistent in frequency and pulse height. This makes the pulses that this tool creates very easy to filter out so that the pulses do not interfere with other tools such as directional tools and (measurement while drilling) MWD tools. As disused above, the maximum fluid pressure is achieved when the piston is in the fluid restricting position. The narrower the restriction, the greater the increase in pressure. The graph of Figure 7 was achieved with a piston of smaller diameter than that used to generate the graph in Figure 8. It will be appreciated that by simply changing the piston and/or orifice diameter, the fluid pulse apparatus of the present invention can be easily tuned.

Alternatively, a piston 29 may be tapered across itself so as to provide a restrictive fluid flow passage 31 on one side of the piston and an unrestricted flow passage on the opposite side of the piston. Further, the fluid flow passage 28 can have an extension of the opening of the fluid flow passage 28 within its wall. The piston fluid flow passage 31 and the fluid extension opening 30 of the fluid flow passage 28 so that a very effective closed position is achieved when the cam follower 18 is in the high point position 32 of the cam surface 19. Once the cam follower 18 rotates around to the low point position 33 of the cam surface 19, the piston fluid flow passage 31 will rotate 180° and axially be lifted so that the piston fluid passage 31 and the fluid flow passage opening 30 are completely miss aligned. Rotating the piston around an additional 180° will return the piston 29 to the aligned open position. The benefits of timing the movement of the piston 31 and the fluid flow passage opening 30 with the cam profiles 15 and 19, allows for a cleaner, more defined and hydraulically adjustable pulse which allows for less turbulent flow so as to achieve a clean pulse. Further adjustments may be made by adjusting the pitch of the turbine and size of the piston while using different fluid property and pumping different gallons per minute, it is possible to adjust the frequency of pulse over a second and to adjust the pulse height to create many different configurations tailored to match different conditions.

Figs 9a and 9b show another piston 29 moving up and down and rotating one revolution during its up and down movement and another orifice 28. This works in the same way as orifice 1 1 and piston 13 however the big difference between the two is that a slot cuts into the side of the orifice 28 and the piston is not pointed but instead it is scalloped from one side to the other.

Fig.10 shows the cam surface that is mounted above and below the turbine sleeve 17 and does not rotate. The cam followers 14 and 18 are apart of the sleeve 17. The cam followers will rotate because the sleeve and turbine are attached to each other. The cam followers, sleeve, turbine and piston are all kept in place via the fixed cam surface and can only rotate.

Due to the interaction of the rotating cam followers following the path of the fixed cam surface, when the turbine 16 is rotating, the cam followers, sleeve, turbine and piston have to move up and down when they rotate over the fixed cam surface located above and below. Fig.2 shows how all the parts are located within the tool. The advantage of this embodiment of the invention is that it can achieve a very sharp pressure pulse by increasing the loose fluid restriction (marked up in Fig.9a and a very tight high fluid flow restriction as noted in Fig.9b.

This is achieved by ensuring that each of the components is timed and lined up during the rotation and up, down movement of the piston 29.

The fluid pulse apparatus does not have elastomers, such as those found in positive displacement motors that are used to drive valves to produce a pressure pulse as per known devices. The lack of elastomers can extend the life of the apparatus while being used in hot hole conditions and when there is abrasive matter being pumped through the apparatus.

Still further without elastomers, non-aqueous chemical fluids can be pumped through the apparatus. Further, without elastomers or seals, the apparatus can tolerate higher pressures.

As a result of the upstream and downstream cam action, the fluid pulses are very consistent in frequency and pulse height. This makes the pulses that this tool creates very easy to filter out so that the pulses do not interfere with other tools such as directional tools and (measurement while drilling) MWD tools.

Unlike other fluid pulse apparatus on the market, the flow control components of the present apparatus only move axially. This in turn means that there is no harmful and unwanted lateral vibration created. Those apparatus on the market that use mud motor technology do create lateral vibration that in turn causes damage to other components that make up and are included within the drill string. The present fluid pulse apparatus can be used with or without a shock tool. An advantage of the present apparatus is that the apparatus without a shock tool can induce a hammer effect on coil tubing which in turn creates axial movement of a coil tubing string.

When the fluid pulse apparatus is used with a shock tool the pulse will react on the pump open area of the shock tool. This will cause the shock tool to axially extend and retract with each pulse. The shock tool can be placed below the fluid pulse apparatus or above the fluid pulse apparatus. If the pump open area of the shock tool is increased, the pulse will have a larger area for the hydraulic force to act upon which in turn will increase the axial extend and retract the shock tool. If the pump open area of the shock tool is reduced, the pulse will have less area for the hydraulic force to act upon which in turn will reduce the axial extend and retract the shock tool. This is known as a hammer effect as described in US 4830122.

It will be appreciated that various changes and modifications may be made to the apparatus as described and claimed herein without departing form the spirit or scope thereof.