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INTRODUCING THE PATENTED DARTT® VALVE SYSTEM
THE DARTT® VALVE ELIMINATES GAS LOCK
THE DARTT® VALVE ELIMINATES FLUID POUND
THE DARTT® VALVE ALLOWS LONGER, SLOWER FULL PUMPING STROKES
THE DARTT® VALVE INCREASES FLUID PRODUCTION
THE DARTT® VALVE INCREASES GAS PRODUCTION
THE DARTT® VALVE ALLOWS EFFICIENT PUMPING OF HEAVY CRUDE
THE DARTT® VALVE CAN HELP IN SANDY CONDITIONS
THE DARTT® VALVE IS BUILT FOR DURABILITY
THE DARTT® VALVE IS EASILY INSTALLED
THE DARTT® VALVE WILL NOT DAMAGE YOUR PUMP
Only the experienced Oilman can fully appreciate the many things which can happen to impede his well from perfectly delivering the oil and gas which he knows is down there. Each well has its own story and each well is as unique as each child in a family. Not only is each well acting in its own way today, but it probably is acting differently today than it did last week, and differently than it will in the future. Gas lock last month, fluid pound and mechanical damage last week, perfect pumping today, but perhaps many pump changes are required this year to keep up production. It is a continual job to keep up with each well; each with its own definite and changeable personality. Frequently, it requires more money to keep a well in production than is realized in production sales. All of these things require the very best in the Oil Patch.
the very best equipment
the very best operators
the very best pump shops
AND the best insight from experienced personnel who
can key in on the slightest of clues and apply their unique "bag of tricks"
built up through years of trial and proving.
Unless oil and gas can be brought to the surface after spending hundreds of thousands of dollars to drill a well, the investment is wasted. Although every part of the well is required to bring production to the surface, the down hole pump is the heart of the well.
While sometimes a down hole pump will deliver no
fluid at all, it is much more frequent that it will pump at least some fluid. What has had
to happen to obtain that fluid has been to: contend with whatever the well has presented
as problems from one day to the next, reading the clues of fluid level, fluid flow, fluid
pound, dynamometer card curve shape, etc. and applying the best equipment and procedures
found over a lifetime of dealing with oil production. Then the accountants take the cost
of production, subtract that from the production sales value, and provide management with
information which frequently results in shutting down a well or selling an entire field.
This is sad for everyone involved to see.
MANY TIMES THE ABANDONED WELL CAN BE PROFITABLE.
The personnel at DARTT®
VALVE spent years observing the many
types of problems which happened to producing wells in an attempt to help resolve and
hopefully, prevent many of them. Although it was observed that some had a few problems
with pumping units and with leaking tubing, the vast majority of production problems seen
were directly associated with the down hole pumps. These problems were observed to be the
same few problems over and over:
Specifically to eliminate these problems, the
The DARTT® VALVE is a hydraulically-operated accessory which is installed within the standard down hole pump without modifications to the pump. The DARTT® VALVE is actuated by the normal fluid or gas pressures which exist within the pump. The DARTT® VALVE takes the guesswork out of whether or not the traveling valve is opening and closing properly. By design, on the upstroke, the traveling valve must close. On the downstroke, the traveling valve must open. The DARTT® VALVE causes both of these actions to positively occur on each and every pump stroke and the DARTT® VALVE does even more...
It is widely recognized that to the expert Operators within the Oil Industry, a tool or method is only considered if a logical explanation of its operation clearly shows what the problem is and clearly shows the solution. Accordingly, the following technical notes are addressed to the Operators within the Oil Patch without whose expert daily application of expertise, production would be impossible.
Let's review some of the reasons why the DARTT® VALVE helps increase
production and reduce production costs.
THE DARTT® VALVE ELIMINATES GAS LOCK
Gas lock has plagued the oil industry since the first ball and seat pump was installed. This century-old problem causes a reduction in fluid production and increases maintenance and equipment costs. In many cases, wells having too much gas or containing fluids with many light ends, which would flash upon being subjected to the relative vacuum of the upward-traveling pump, would not pump fluid at all. The pump would soon be destroyed within the barrel due to lack of fluid lubrication. Either way, until the introduction of the DARTT® VALVE, which is specifically designed to operate in the gas environment, the gas lock problem could not be effectively eliminated. Now, the addition of a DARTT® VALVE to the pump will eliminate gas lock.
To discuss gas lock meaningfully, it is necessary to review the normal operation of the pump and describe the abnormality of gas lock.
NORMAL PUMP OPERATION
In normal pump operation, the plunger of the pump is in the down position and begins to move upward. The traveling valve within the plunger is closed, and a low pressure area is formed in the void where the plunger had been. The higher pressure (may require high fluid level) just outside of the pump forced the standing valve to open. With the standing valve open, the void within the pump is filled with fluid. When the plunger reaches the top of the stroke and starts downward, the pressure inside of the pump exceeds the pressure outside of the pump, and the standing valve is forced closed. This forms a closed chamber within the pump barrel, with the standing valve at the bottom and with the traveling valve at the top.
As the plunger continues downward, it attempts to compress the liquid, which is non-compressible; thus causing pressure within the closed chamber. which pushes against the bottom of the traveling valve ball, exerting a force to open the ball. When this force is great enough to exceed the force pushing on the traveling valve ball from the fluid column above the pump, the traveling valve ball opens. As the plunger continues downward, the fluid within the chamber escapes through the open traveling valve into the column of fluid above the pump. When the plunger reaches the bottom of the pump, the traveling valve closes and the plunger again starts upward. This creates a relative vacuum within the pump barrel, opening the standing valve, and allowing fluid from the well to enter the pump.
GAS LOCK - WHAT HAPPENS
In the real world, "normal" pump operation is unusual and when it does happen, it does not continue for long. One of the common occurrences which prevents normal operation is gas lock. During gas lock, the plunger of the pump is in the down position and begins to move upward. The traveling valve within the plunger is closed and a low pressure area is formed in the void where the plunger had been. The higher pressure just outside of the pump forced the standing valve to open. With the standing valve open, the void within the pump is filled with gas instead of fluid. When the plunger reaches the top of the stroke and starts downward, the pressure inside of the pump exceeds the pressure outside of the pump, and the standing valve is forced closed. This forms a closed chamber within the pump barrel, with the standing valve at the bottom, and with the traveling valve at the top.
As the plunger continues downward, the volume within the closed chamber decreases and forces the gas within the closed chamber to become compressed. Since gas can be compressed, this gas merely becomes compressed and does not push against the bottom of the traveling valve ball hard enough to cause a force to open the ball. Since this force is not great enough to exceed the force pushing on the traveling valve ball from the fluid column above the pump, the traveling valve ball never opens and the gas within the closed chamber remains there. When the plunger reaches the bottom of the pump, the traveling valve is still closed, and the plunger again starts upward. But this time, instead of creating a relative vacuum within the pump barrel, the compressed gas within the closed chamber merely becomes less and less compressed. No relative vacuum is formed to open the standing valve and no fluid from the well enters the pump barrel. This cycle is repeated until the pump literally wears out from the friction of the un-lubricated plunger against the pump barrel. At this time, the pump must be pulled and replaced.
DARTT® VALVE - THE CURE FOR GAS LOCK
What went wrong in the "gas lock" cycle? Once we identify what went wrong, then we can work to fix it. Well, what went wrong was that the gas was allowed to remain within the pump, instead of forcing it on up through the pump as if it were normal fluid. The gas stayed within the pump because the traveling valve never was forced to open. So, to fix the problem, we must open the traveling valve every time the plunger begins its downward stroke and keep it open throughout the entire downward stroke. Also, insufficient relative vacuum between the interior of the pump and the well existed to force the standing valve to open. Therefore, to fix this problem, we must cause more relative vacuum to be formed as the plunger travels within the upward direction. Both of these problems work hand in hand with one another, the one causing the next, which causes the next, and so on.
Accordingly, the solutions to these two problems must also work hand in hand, one preventing the first problem, thus preventing the next problem, and so on.
What would logically work to prevent these two problems would be a device of some sort which would positively open the traveling valve on the down stroke and which would positively close the traveling valve on the up stroke. Absolutely closing the traveling valve on the up stroke would create the best possible relative vacuum between the pump interior and the well; thus, doing the best job possible to force the standing valve to open in the upstroke. Positively opening the traveling valve in the down stroke would empty the pump and prevent gas compression within the pump. This correctly and perfectly sets the stage for filling the pump once again in the following up stroke.
Since pressure is presented in pounds per square inch, the force which the pressure exerts against the traveling valve to open it should logically be increased. if one were to cause the natural pressure within the pump to push against an area which is larger than the small area within the seat below the traveling valve, and then use this larger force to force the ball to open. The DARTT® VALVE makes use of this simple principle of hydraulics: the pressure pushing against a larger area to make a larger force, to positively force the traveling valve to open every time the plunger begins its downstroke. The DARTT® VALVE keeps the traveling valve open with this force throughout the entire down stroke.
In the up stroke, with the inside of the pump now empty, the traveling valve and the three cascade valves within the DARTT® VALVE positively shut and form a nearly perfect relative vacuum within the pump. The pressure differential between the inside of the pump and the outside of the pump in the up stroke now causes the standing valve to open, positively filling the pump with whatever is within the well.
This sequence of operations changes the standard plunger pump from one which can only
pump fluid to one which can also pump gas. Now, we recognize that the operator would go
broke trying to pump gas, but with the DARTT® VALVE
installed within his pump, he could literally pump gas. The key here is to pump the gas
long enough to prime the pump, sucking in gas and then gas/fluid emulsion, and finally
fluid; thus preventing gas lock. Any time later
in the life of the well if gas were to return to the flow to a great extent, the pump
would continue to pump just as it should, regardless of the gas content in the
well.
THE DARTT® VALVE ELIMINATES FLUID POUND
NORMAL PUMP OPERATION
As the plunger begins to travel downward, it attempts to compress the fluid, which is non-compressible; thus causing pressure within the closed chamber, which pushes against the bottom of the traveling valve ball, exerting a force to open the ball. When this force is great enough to exceed the force pushing on the traveling valve ball from the fluid column above the pump, the traveling valve ball opens. As the plunger continues downward, the fluid within the chamber escapes through the open traveling valve into the column of fluid above the pump.
FLUID POUND - WHAT HAPPENS
Once again, we have observed that in the real world, "normal" pump operation is unusual and when it does happen, it does not continue for long. Another one of the common occurrences which prevent normal operation is the partial filling of the pump with gas instead of completely filling the pump with liquid. Immediately before the impending fluid pound strike, the plunger of the pump is in the up position and begins to move downward. Moving downward with the plunger are the rod string and the pumping unit mechanical system. All of which have mass and momentum.
Within the pump barrel, is some gas and some liquid. The gas, being lighter than the liquid, floats on the liquid; therefore, it is above the liquid. As the plunger begins its downward travel into the barrel of the pump, it travels only through gas. The gas is compressible and presents no opposition to the falling plunger and rod string mass. The falling plunger and rod string mass travel virtually unopposed toward the liquid in the lower portion of the pump barrel. The traveling valve remains closed due to the greater force from the above liquid column within the production tubing compared to the small force presented by the gas pressure against the very small area of the traveling ball valve within the seat. No gas or liquid is escaping yet from the closed volume within the pump because the traveling valve is still closed.
Eventually, the falling plunger meets the liquid, which is incompressible, and
instantly stops. The plunger stops, the rod string attempts to stop, but actually
compresses like a spring, snaking and bending within the tubing all of the way up to the
surface. Meanwhile, the pumping unit attempts to continue in the downward direction, but
instantaneously it can not. The mass of the fluid above the traveling valve ball stopping
instantaneously causes the traveling valve ball to seal even more tightly during this
instant. The liquid, by nature, can not be compressed. All of these forces come together
to oppose one another during an instant. These forces are called transients. And this
instant is repeated on every stroke...until something breaks. During observations of many
such situations, the resulting fluid pound shattered or cracked steel traveling balls of
up to 2 1/4" in diameter, broke ball cages in all directions, and caused "rod
shock", which breaks rod strings, particularly those having hydrogen embrittlement
due to H2S in the well. These cracked balls and broken cages were collected and are
available for examination upon request. All of these things occurred simply because the
traveling valve was not opened when it should have been.
DARTT® VALVE - THE CURE FOR FLUID POUND
What went wrong in the "fluid pound" cycle? Again, once we identify what went wrong, we can work to fix it. Well, what went wrong was that the gas within the pump did not present sufficient force to the underside of the traveling valve to open it as it would have opened had the pump been full of fluid. So, to fix the problem, we must open the traveling valve every time the plunger begins its downward stroke and keep it open throughout the entire downward stroke.
What would logically work to prevent this problem would be a device of some sort which would positively open the traveling valve immediately upon the plunger beginning the down stroke and which would positively keep the traveling valve open throughout the entire down stroke.
Positively opening the traveling valve in the down stroke would prevent the instantaneous shock of attempted fluid compression within the pump in the down stroke. Instead this would allow the fluid within the pump to simply leave the pump normally into the production tubing above the pump.
Since pressure is presented in pounds per square inch, the force which the pressure exerts against the traveling valve to open it should logically be increased if one were to cause the natural pressure within the pump to push against an area which is larger than the small area within the seat below the traveling valve, and then use this larger force to force the ball to open. The DARTT® VALVE makes use of this simple principle of hydraulics, the pressure pushing against a larger area to make a larger force, to positively force the traveling valve to open every time the plunger begins its down stroke. The DARTT® VALVE keeps the traveling valve open with this force throughout the entire down stroke. Thus, the simple addition of the DARTT® VALVE to the pump eliminates fluid pound. The net result is reduced in stress on the traveling valve ball, reduced stress on the sucker rods, smoother strokes, longer pump life, fewer sucker rod failures, fewer tubing leaks, fewer pumping unit gear box failures, and lower overall maintenance costs.
Note that with the DARTT® VALVE, the practice of "tagging the pump" in an attempt to jar the ball off of the valve seat are not needed; therefore, the maintenance costs caused by the violent forces set in motion during pump tagging are eliminated. Historically, the operator is reprimanded
for not making production. The operator is also reprimanded for tagging the pump. So if the operator has to tag the pump to get production, he cannot tell this to his supervisor. Communication on this topic is suppressed for obvious reasons. Of course tagging the pump puts more stress on the rods, tubing, gear boxes, etc..
One might ask: Where did the gas come from which caused the fluid pound in the first place?
Field investigations have shown that the gas comes from four main sources:
1. Gas from the formation coming into the pumping chamber
2. Gas formed from the "light ends" of the production fluid being exposed to the relative vacuum within the pumping chamber during the up stroke of the plunger.
3. Gas formed from the "light ends" of the production fluid being exposed to the relatively high-temperature of the pump barrel which has been in contact with the moving plunger.
4. Gas formed by the constant movement of the plunger in the barrel which causes gas to break out of solution (similar to that observed after shaking a bottle of soda pop).
Observation of these gas sources shows that there is little, if any, that even the most
experienced operator can do to eliminate these gases. The best thing that the operator can
do is to be ready to deal with them. The DARTT® VALVE is the very best tool available today to deal with
these inescapable realities.
THE DARTT® VALVE ALLOWS LONGER, SLOWER FULLY LOADED PUMPING STROKES
It has been observed that many wells are pumped at 10 - 16 strokes per minute to insure that conventional ball and seat valves are working. Experience shows that rod stretch becomes a significant factor in the movement of the plunger relative to the movement of the pumping unit. With very deep pumps, the stroke length of the plunger within the pump bears little relationship to the stroke length at the surface. Accordingly, with fast stroke rates, control of the plunger within the pump becomes less predictable, and stress on the rods and the increased cost of electricity become less desirable as well.
With the DARTT® VALVE, the stroke rate can be lowered to 6 or even less because of the positive opening and closing features of the traveling valve. The results of installing the DARTT® VALVE are:
the effective stroke length down hole at the pump tends to be increased to its maximum
the load and demand put on the electric motor are dramatically reduced
the cost for the reduced kilowatt-hour energy demand per barrel of oil produced are reduced accordingly.
THE DARTT® VALVE INCREASES FLUID PRODUCTION
It has been observed that, in an effort to minimize flash-gas and the resulting fluid pound, it has been the practice of most operators to maintain a level of fluid within the well to the 300 - 500 feet range. The actual level is frequently dictated by the Pump-Off Controller which shuts down the well upon sensing fluid-pound vibration. The problem is that although the pump is then shut down, the well is not really pumped off. Worse, the high level of fluid left in the well presents hydrostatic pressure pressing against the formation, hampering the formation from delivering its fluid to the well.
LOGICALLY, IF ONE COULD EMPTY THE WELL OF FLUID, THEN THIS WOULD RELIEVE THE BACK-PRESSURE ON THE FORMATION AND ALLOW THE WELL TO DELIVER AN INCREASED FLOW RATE TO THE PUMP.
When one installs a DARTT® VALVE into the pump, fluid pound is eliminated and
the tight-valving of the DARTT® VALVE system literally sucks all
fluid in the well into the pump. Thus, pumping right down to the seating nipple is
possible and becomes the normal mode of operation when using the DARTT® VALVE. In most wells reviewed after installing the DARTT® VALVE, relieving the pressure on the formation has resulted in increased fluid
production.
THE DARTT® VALVE INCREASES GAS PRODUCTION
A common practice in the Oil & Gas industry is: to " Kill a well, fill it with salt water". Then the well can be worked on. Logic dictates that the reverse is true: "To produce all of the gas possible from a well, remove all of the salt water from the well, and expose the formation to the empty well."
In gas wells, it has been observed that high levels of water frequently exist within the wells. Any water above the seating nipple reduces the quantity of gas which can be produced. We have noted that a water level reduction of only ten feet can make dramatic increase in gas production. These high levels of water are frequently required because of the fluid pound which exists when attempts are made to pump the water to a lower level. This is because of the great quantity of gas within the water.
The addition of a DARTT™ VALVE to a pump allows an operator to pump all
of the water from the well right down to the seating nipple with no fluid pound
problem. In all wells reviewed after installing the DARTT™ VALVE, relieving the pressure on the formation has
resulted in marked increases in gas production. THIS SYSTEM CAN BE TIME CLOCKED FOR POWER
SAVINGS WITHOUT FEAR OF GAS LOCK WHEN THE PUMP STARTS BACK UP.
THE DARTT® VALVE ALLOWS EFFICIENT PUMPING OF HEAVY CRUDE
In most heavy crude production, conventional balls float off their seats as if suspended in a weightless environment; thus preventing the pump from loading during the up stroke. Further, in crudes having gravities of 10 - 18, problems have been recorded of the traveling valve at times sticking closed due to the surface tension between the ball and seat. While these problems, when viewed from the surface, seem to indicate gas lock, what is actually happening within the pump is the exact opposite of gas lock. Only the symptoms are the same.
The installation of a DARTT® VALVE backs up the traveling valve in operation .
When the traveling valve ball has floated off the seat in the heavy crude and the pump is
in the up stroke, the DARTT® VALVE performs the job of closing the bottom of the plunger so that more crude
can be sucked into the pump through the standing valve. Also, when the surface tension of
the heavy crude has practically glued the traveling valve ball to its seat and the pump is
in the down stroke, the DARTT® VALVE forces the traveling valve to
open. Thus, the installation of a DARTT® VALVE in heavy crude increases production and, in some
wells, makes production possible where it would be impossible without the DARTT® VALVE.
THE DARTT® VALVE IS BUILT FOR DURABILITY
The DARTT® VALVE is normally constructed from high grades of stainless steel which are NACE materials and are suitable for corrosive conditions. The normal material of which the DARTT® VALVE is made exhibits a yield strength of in excess of 100,000 psi. Thus, making it strong enough to survive in the event that the traveling valve were to fail. In most applications, the DARTT® VALVE is protected from well pressures by the conventional ball and seat.
In the event that a certain unusual condition is encountered and special metallurgy is
required, DARTT® VALVES are available in specialty metals as well.
The natural operation of the DARTT® actuator as it lifts the traveling valve ball from its
seat with an inclined plane causes the ball to pivot and to spin. This large amount of
spinning helps to keep heavies like sand in suspension. But even more importantly, one of
the true beauties of the DARTT® VALVE is that it
causes fluid to flow on every stroke, not giving sand a chance to become embedded in the
sealing surface between the ball and seat. The DARTT® actuator action
works on every stroke to help keep the pump from plugging with sand.
THE DARTT® VALVE IS EASILY INSTALLED
DARTT® VALVES are available
in most common pump sizes: 1 1/4", 1 1/2", 1 3/4", 2", 2 1/4",
and 2 3/4", and can be easily fitted to existing API hardware by simply threading the
DARTT® VALVE onto the
traveling valve double female cage. Other sizes are available by special order. DARTT® VALVES are
available for plunger pumps, tubing pumps, and traveling barrel pumps.
THE DARTT® VALVE WILL NOT DAMAGE YOUR PUMP
Although the DARTT® actuator within the DARTT® VALVE comes into contact with the traveling valve ball, the DARTT® actuator will not damage the ball. Everyone in the Oil Patch recognizes how important it is that the ball be perfect and undamaged. The DARTT® actuator has been specially heat treated to make it a relatively soft, Rockwell 37 hardness. The traveling balls are supplied in the range of Rockwell hardness between 55 and 300. Further, the DARTT® actuator only impacts the ball as a wedge, not as a direct blow. The valve timing within the DARTT® actuator valve is set up so that the energy available from the DARTT® actuator at the moment of contact with the ball is momentum energy from pressure forces earlier within the stroke. Finally, and most importantly, this impact is in the upward direction, forcing the ball away from the seat.
SINCE THE VALVE IS OPEN IN THE DOWNSTROKE, SPRAY FROM THE PRODUCED FLUID ABOVE THE PLUNGER LUBRICATES BELOW THE PLUNGER AND HAS SHOWN TO OPERATE AT THE SEATING NIPPLE WITHOUT DAMAGE. (This is the true pumped off condition)
From a hardware
installation standpoint, great care has been taken to shape the DARTT® VALVE to allow it to work with all
standard traveling valve seats. The cylinder body of the DARTT® VALVE is manufactured to simply be screwed onto standard API double female
valve cages and to be tightened with standard friction wrenches.
DARTT™ VALVE CO., Ltd. has done everything possible to pay attention to every detail in meeting the needs of the Oil Production Operator in the operation, construction, and installation of DARTT® VALVES. Throughout development and during initial field proving, the comments and suggestions of a great many Operators were incorporated into DARTT® VALVES. The result is that DARTT® VALVES are among the finest and most useful Oil Tools available to the Oilman today.
DARTT® VALVES are available for rod pumps, for tubing pumps, and for traveling barrel pumps.
DARTT® VALVES are normally available by UPS overnight by simply:
Calling DARTT™ VALVE CO., Ltd. at (713) 896-1113
or
Faxing your order to DARTT™ VALVE CO., Ltd. at (903) 561-2385
or
Calling Joe Nelson (903) 253-2255 cell
If your needs are extremely urgent, delivery by air to the airport nearest your location is also available.
Relieve the strain on your pumping equipment, on your maintenance pocketbook, and on yourself...Begin to rely on DARTT® VALVES as your oil tool of choice.
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