POSITIVE PRESSURE RELEASE VALVE

SOUPAPE DE SURETE A SURPRESSION

English Abstract

In the oil industry, positive displacement motors are attached to the bottom hole assembly(BHA)
mechanism to provide additional power to the bit. The motor is turned through the hydraulic force
of the drilling fluids that are circulated within the drill string. However, once the bottom hole
assembly becomes blocked, fluid can no longer circulate through the bit and back to surface.
Serious problems arise as a result of this loss in circulation . In severe situations, this condition
makes it possible to break off and lose the drilling pipe in the well bore.
The need for a remotely activated release valve to restore circulation within the well is critical.
The technical knowledge disclosed within this application relates to a mechanical device that is
designed to release the fluid trapped inside the drilling pipe once the bottom hole assembly has
become blocked, thereby restoring circulation..
The Positive Pressure Release Valve is activated through a increase in fluid pressure created by the
surface pumps. Once a certain internal pipe pressure is achieved, the release valves are
permanently released and circulation is restored within the pipe and well bore.
The drill pipe is now in a position to be removed with minimal interruption and damage.

French Abstract

En exploitation pétrolière, il existe un procédé de forage dans lequel l'outil de forage est entraîné par une turbine placée entre celui-ci et le train de tiges et actionnée par la circulation des boues passant dans le train de tiges. Cependant, lorsque l'outil de forage grippe, les boues ne peuvent plus circuler dans celui-ci et remonter à la surface, ce qui cause de gros problèmes pouvant aller jusqu'à la rupture et à la perte de la tige de forage. Il faut donc que soit prévu un moyen commandé à distance pour rétablir la circulation des boues dans le forage. La présente invention concerne un dispositif mécanique permettant de rétablir la circulation des boues captives dans la tige de forage en cas de grippage de l'outil de forage. Ce mécanisme est actionné par la surpression des boues engendrée par les pompes de surface. Lorsque la pression à l'intérieur de la tige de forage atteint une valeur déterminée, les soupapes de décharge s'ouvrent et demeurent ouvertes, et la circulation se rétablit dans la tige de forage et le puits. La tige de forage peut alors être retirée avec le minimum de risques et de temps d'arrêt.

Claims

WHAT IS CLAIMED:
The embodiments of the invention in which an exclusive property or privilege is claimed
are defined as follows:
1. A Positive Pressure Release valve can be constructed through the information presented within
this application.
2. This Positive Pressure Release valve is designed for use in any application that requires a
fluid/slurry to be passed down a pipe that is used in the recovery and exploration of
hydrocarbons.
3. Primary to Positive Pressure Release valve's design is a plug connected to a web secured in a
carrier.
4. The plug is thicker than the web and meets the web with a certain angle. The critical nature of
this angle is that it must be less than 90 degrees.
5. The web is defined as a portion of the plug that has been reduced in thickness so as to create a
localized increase in stress. This web can be of any width. The thickness of this web when
using the American standard pipe brass socket plug is 0.025 inch for 3,000 psi, 0.030 for 4,000
psi and 0.035 for 5,000 psi.
6. The host for the web is called the carrier. This may either be an insert as outlined above, or
may be incorporated directly into a supporting structure such as a sub.
7. The Positive Release Valve may incorporate any material, this decision is based upon the
operating conditions for the Positive Release Valve. Once the material is changed, the thickness
of the web will need to be recalculated and tested.

Description

2 ! 77088
SPECIFICATIONS:
Field of Invention:
This invention relates to ~ihlAtinn~ that occur when drilling operations become hindered by a
blocked bottom hole assembly(BHA). Under normal drilling operations, surface pumps pl~S:!iul~;
the drilling fluid to applu~ ldlely 500 psi under normal situations, with a IllAXi.u..~ pumping
plt;S~Ult; of around 3,000 psi. Under these conditions, the flow through the motor and the bit
provides enough of a ples~ult; drop so as to allow the fluid circulation to be controlled. This
circulation is critical since the drilling fluid has to perform several fimction~ The most important
of these is to remove the drill cutting from the bit and well bore. The second fiunction is to provide
power to the hydraulic motor in the BHA.
In the event the BHA becomes blocked there are two problems that effect the retrieval of the
drilling pipe. The most important is the li~ ial p.~s~u-~; created at the bottom of the hole when
the pipe is pulled back to surface. This force might be so great that either the rig cannot pull the
pipe out of the hole, or the drilling pipe itself might break. The second problem is the ~ itinnAl
time required to catch the fluid trapped within the pipe every time the sections are broken apart,
this is known in the industry as a "wet" trip.
The Positive Pressure Release Valve is an il,lpol~u-l safety device for the drilling pipe that
provides insurance against allowing the pipe becoming stuck as a result of a blocked downhole
motor. In addition to the drill string and the BHA, there are other pieces of eql-ipm~.nt near the
BHA that are very expensive, in some cases the MWD tools can run as high as $500,000 to
replace. The ability to retrieve this eqllirm~Mt is another important factor that must be taken into
consideration should the drill string have to be ~b~n(lnnP~1

2 1 77~88
Description of Prior Art:
Pl~s~ ly existing in the oil industry, is a downhole pl~iS:iUl~ release device the uses pin to hold the
release valves in place. Once circulation is blocked, a wireline tool is sent down to shear the pins,
thus activating the release valve.
This technology however is outdated, only working in situations that permit the use of gravity
assisted wireline tools. In today's drilling ~nvilu~ substantially more wells are being
directinn~lly drilled, and the use of gravity assisted wireline tools are limited to hole angles less
than 40 degrees (from the true vertical angle being 0 degrees). Many wells today and especially
those that encuulll~l blocked circulation are horizontal wells and are therefore unserviceable
through the use gravity assisted wireline tools.
A second method of wireline propulsion is through circulating the drilling fluid to push the wireline
out into the horizontal section. This method however requires the ability to circulate the drilling
fluid, and in ~itll~tinn~ that require this device, this technique is not possible since circulation is
blocked.
This obvious limit~tion makes the shear pin pltis~ul~; release valve ineffective in today's modern
drilling environment.
Summary of Invention:

2 1 77088
The novelty and h~t;nuily of this invention is the ability to remotely trigger the pl~s~ul~ release
valve from surface without ever having to physically touch the release m~h~ni~m This saves
considerable time in retrieving the blocked motor or other downhole tools, which nltim~tely saves
money.
This remote triggering of the release valve takes advantage of the pressule di~~ Lial between the
inside of the pipe and the well bore. The plt;s~ulti in the pipe is directly controlled at surface
through the pumps. The pressure of the fluid in the well bore is a direct function of the vertical
well depth . Since this Lydros~lic pressure is the same inside and outside the drilling pipe,
al1l1ition~1 pl~;S~ult; applied to the fluid inside the drill pipe will allow for the lu~lulillg of the
release valve.
It is critical to this design that once the release valve has been triggered that it completely remove
itself from the valve so as not for further hinder the flow of the fluid. In order for this to be
accomplished effectively, there are several factors that need to be taken into consideration:
di~l~ ial pltiSSUI~ across the valve, area of plug, material composition of web, thickness of web
and taper angle of the plug.
DESCIPTION OF DRAWINGS:
Figure I . Cross section of pl~iS~w~ release valve
Figure 2. Plan view of ples.,w~ release valve
Figure 3. Positive Pressure Release Sub

2 1 7708~
**NOTE**
NAMING CONVENTION:
In the context of this application, the followin~ tPrmin~ln~y will be employed. To identify parts that
co~ ,ond to the above drawin~s, theY shall be i/lPntifiPd throu~h the followin~ convention. First the
drawin~ number, presented in Roman Numerals, and then the Part referenced on that drawin~. For
example IIC refers to part C as shown on fi~ure 2.
The concept crucial to this invention is the creation of a web IA that is m~(~hinPd to a precise
thi~knPss based on a host material so as to provide a pl~id~ ed amount of strength. ConnPcted
to the web is the end plate IB which provides the surface area for the interface between the inside
and outside pleSSUIeS. The angle where the plug meets the web is an important pd~ ler since
this zone increases the stress applied to the web. In ~d-lition, once the load has Px~eeded the
carrying capacity of the web, this taper angle makes sure that the plug does not get caught in the
release valve as it is ejected into the well bore. This prevent the release valve from partially
opening and llnnecess~rily restricting the fluid flow..
This release valve can be incorporated into any eql-ipmP,nt that is to be ~t~ hPd to the BHA. It is
generally recogni7Pd that this release valve will be incol~ol~ted into an insert that is screwed into a
special housing contained within a sub, see Figure 2. The insert or multiple inserts incorporated
into a downhole tool is referred to as a Pressure Release Sub, see Figure 3.
On incorporating this release valve in a sub, it is important that, should more than one be used, the
valves are not placed at the same level. Should the insert be located at the same height in the sub,
the re l~1cticn in cross sectil-n~l area will result in serious strength degradation of the tool, possibly
causing it to fail.

2 1 77088
The insert is not tapered and is secured with a seal at the toe in order to prevent the insert from
dislodging itself during operation. The heel of the insert is m~hinr.d to allow a 1/2" drive to
tighten and remove the insert from the sub. The 1/2" drive size is the most comm- nly available
drive on a rig. This also provides reusability of the Positive Pressure Release Sub by replacing the
released valve with on that is new. This will save both time and money.
The thickness of the web that is critical to the ptilro~ ce of the release valve is ~ e~ . l .inFd by the
following chart
Rating PSI Thirl~nFc~
3,000 0.025
4,000 0.030
5,000 0.035
These values are for 3/4" American standard pipe, brass socket plug, coll~ ial type.
Once the material is cll~ngF~rl the thirl~nes5-strength rel~tion~hir will change accol~ g to the
selected material. Other material that may be used with this type of system are:
Stainless steel
Monel

Representative Drawing