Wells used in steam assisted gravity drainage (SAGD) and cyclic steam applications are subjected to heating of their wellbores for an extended period of time with heated fluid and/or steam, In many of these thermal wells, a liner top packer is deployed and set during the final completion of the well, The liner top packer is deployed to a specific depth with a tubing string. Once at the specific depth, the liner top packer is set by pressurizing fluid within the tubing string to a specific value. A system in the packer or in a separate setting tool translates the fluid pressure into an axial force and axial movement which energizes the packer sealing element and the packer slips (if the packer design includes slips). Due to the nature of thermal wells, the wellbore and liner top packer can experience several severe temperature and pressure fluctuations which can degrade the pressure integral seal of the packer sealing element. For example, the heating and cooling of the packer sealing element can relax the internal. stresses that were created during setting of the packer sealing element thus creating a compromised seal element which no longer maintains the pressure integral seal.
In general, the present disclosure provides for a system and method of actuating an energized device, such as a packer. The technique provides an actuating force with a thermally expandable material located in a container. The thermally expandable material is operatively coupled with an element, such as a packer sealing element, via an actuator member. When the container and the thermally expandable material are positioned in a high heat environment, the thermally expandable material expands and actuates the element via the actuator member. In packer applications, the thermally expandable material may be used to continuously energize the packer sealing element and/or other components while the thermally expandable material. is positioned in the high heat environment.
However, many modifications are possible without materially departing from the teachings of this disclosure. Accordingly, such modifications are intended to be included within the scope of this disclosure as defined in the claims.
Certain embodiments of the disclosure will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements. It should be understood, however, that the accompanying figures illustrate the various implementations described herein and are not meant to limit the scope of various technologies described herein, and:
In the following description, numerous details are set forth to provide an understanding of some embodiments of the present disclosure. However, it will be understood by those of ordinary skill in the art that the system and/or methodology may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible.
The present disclosure generally relates to a system and method for actuating an energized device, such as a packer. The technique utilizes a thermally expandable material enclosed in a container such that heat added to the material causes an increase in pressure within the container and an expansion of the material. Expansion of the thermally expandable material can be used to perform designated operations. For example, the thermally expandable material may be operatively coupled with an element, such as a packer sealing element, via an actuator member. When the container and the thermally expandable material are positioned in a high heat environment, e.g. a thermal well environment, the thermally expandable material expands and actuates the element via the actuator member. In packer applications, the thermally expandable material may be used to continuously energize the packer sealing element and/or other components while the thermally expandable material is positioned in the high heat environment.
In a variety of packer applications, energizing a packer sealing element involves compressing (squeezing) the sealing element with an axial setting force which extrudes the sealing element radially outward until it contacts a surrounding wall, e.g. a surrounding casing wall. Energizing the packer sealing element creates substantial internal stresses in the sealing element via the compressive force. The compressive force translates into large contact stresses at the boundaries of the sealing element and cooperating components, e.g. at the inside surface of the surrounding well casing and the outside surface of the packer mandrel. A correlation exists between the amount of contact stress at these boundaries and the pressure integrity of the seal. The thermally expandable material can be used to ensure that a sufficient amount of setting force (stress) is contained in the sealing element and that the pressure integral seal established by the sealing element is maintained. In some applications, an additional locking mechanism, such as a body lock ring/ratchet can be used to maintain the setting force and hold the axial travel of the packer sealing element.
Depending on the specific application, the thermally expandable material may be used in liner top packers employed in thermal wells and other well applications. In at least some of these applications, once the liner top packer has been set, the tubing string may be disengaged from the set liner top packer. The tubing string is then removed from the wellbore while the set liner top packer remains downhole in the wellbore.
The thermally expandable material may be employed in a variety of thermal well applications to facilitate actuation of energized devices, such as packers. An example of a lifecycle for a thermal well may comprise four stages including warm-up, injection, production, and shut-in. Throughout the life of a thermal well, the four stages can repeat themselves multiple times, and at each of the stages there is an associated maximum temperature and pressure experienced by the liner top packer, During certain stages, such as the injection and production stages, the liner top packer can experience the highest temperatures and pressures of the cycle.
By utilizing the thermally expandable material to actuate the liner top packer or other type of packer, dependable actuation and/or maintenance of the actuating force on the packer seal element may be maintained throughout the temperature and pressure changes that occur during the thermal well stages. According to an embodiment, a volume of the thermally expandable material is incorporated into a packer piston system or setting mechanism to initially energize/actuate the packer and/or to continuously energize the packer sealing element. The thermally expandable material enables conversion of thermal energy present in the wellbore environment into kinetic energy in a controllable and predictable manner without intervention from the surface. The kinetic energy may also be utilized to actuate various other devices and mechanisms downhole in a wellbore without any intervention from the surface. Examples of actuating such devices and mechanisms include engaging and/or disengaging packer slips, locking and/or unlocking various mechanisms, opening and/or closing ports, energizing seals, rupturing a pressure integral membrane, and actuation of various other devices.
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In the example of
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The piston 44 is moved in an axial direction by the thermally expandable material 36 disposed in a self-contained volume 52 defined by a container 54. In the example illustrated, the container 54 is created by inner tubing 46 and external housing 48 which are constructed to create the self-contained volume 52 therebetween. The self-contained or confined volume 52 may be annular in shape and may extend around the circumference of inner tubing 46. At one end of the self-contained volume 52, piston 44 is exposed to the thermally expandable material 36. When exposed to sufficient heat, such as the heat experienced in a thermal well application, thermally expandable material 36 expands and builds up sufficient pressure within container 54 to shear the shear member 50 and release piston 44. Continued expansion of the thermally expandable material 36 causes movement of piston 44 which transitions the packer sealing element 32 from the de-energized state illustrated in
The thermally expandable material 36 is selected to have a higher thermal expansion value, e.g., a higher coefficient of thermal expansion, than that of the material forming container 54. In the example illustrated, the thermally expandable material 36 is contained in volume 52 and pressure sealed. The actuator 33 translates the pressure generated by the thermally expandable material 36 into an axial force and axial movement of, for example, piston 44. It should be noted that the force and movement resulting from the expansion of thermally expandable material 36 can be used to actuate various devices and mechanisms, including various devices and mechanisms in the packer 42. As described above, the thermally expandable material 36 may be used to actuate/energize both the sealing element 32 and the slips 35 (see
By way of example, the thermally expandable material 36 may be in the form of a liquid with a high thermal expansion coefficient and a low bulk modulus value. Additionally, the liquid may be thermally stable in that the liquid does not degrade at elevated temperatures and the liquid does not react violently, e.g. explode, at elevated temperatures. Examples of thermally expandable material 36 include dimethyl polysiloxane, commercially available from Dow Chemical Company of Midland, Mich., USA under the trade name Syltherm 800™, and DI-2 ethylhexyl sebacate, commercially available from The HallStar Company of Chicago, Ill., USA under the trade name Monoplex DOS™.
During heating of the liquid/thermally expandable material 36, the density of the liquid begins to decrease as the liquid expands. Because the density is decreasing and the thermally expandable material 36 is confined in the self-contained volume 52 of container 54, pressure builds within container 54. The pressurized, thermally expandable material 36 acts on piston 44 and drives piston 44 into packer sealing element 32 to axially compress the element. As long as the thermally expandable material 36 remains heated, the self-contained volume 52 remains pressurized to continuously energize the packer sealing element 32 and/or other energized elements. When the thermally expandable material 36 begins to cool, the material increases in density and reduces the pressure within container 54. As a result, the energized element, e.g. sealing element 32, is de-energized. (In some applications, however, a locking element may be used to retain the packer sealing element 32 and/or other elements in the set configuration. For example, a locking body may be located in piston traps to retain the setting force in the energized element, e.g. sealing element 32.) Effectively, the thermally expandable material enables the energized device 30 to be initially energized and then continuously maintained in that state of energization while the thermally expandable material 36 is exposed to sufficient heat. The process of energizing the packer or other element can be accomplished without an additional intervention process from the surface.
It should be noted that thermally expandable material 36 is readily usable in thermal well applications due to the normal heating of such wells during recovery of hydrocarbons. In various thermal well applications, the wellbore temperature and pressure can vary greatly over the life of a well, however such fluctuations have limited detrimental effects on the packer 42 which incorporates the thermally expandable material 36 to continuously energize the packer sealing element 32. The thermally expandable material 36 is able to utilize the available elevated temperature in the wellbore during the injection and production stages of a thermal well application to assist in creating a more robust pressure integral seal for withstanding the higher pressure present during these stages.
Referring generally to
However, the energized device system 28 also comprises a supplemental actuation system 56 which works in cooperation with the thermally expandable material 36. By way of example, the supplemental actuation system 56 comprises a supplemental actuator/actuation region 58. The supplemental actuator 58 utilizes a supplemental force generating mechanism, such as pressurized fluid acting against a supplemental pressure piston to generate a complementary axial force and movement. By way of example, the supplemental force generating mechanism may comprise a tubing string 60 which delivers pressurized fluid to the supplemental pressure piston in a manner which provides additional axial force in combination with the axial force provided by the thermally expandable material 36. In packer applications, the pressurized fluid may be delivered through tubing string 22 or through an annulus surrounding tubing string 22. In some applications, thermally expandable material 36 is utilized as a setting or energizing booster in addition to providing a mechanism for continuously energizing packer sealing element 32.
Referring generally to
During movement of the energized device system 28 into wellbore 26, the packer sealing element 32 is in a de-energized or radially contracted state, as illustrated in
The thermally expandable material 36 may be utilized in a variety of applications and in many types of environments. Additionally, the energized device system 28 employing the thermally expandable material 36 may be used to supplement or replace other technologies. For example, the energized device system 28 may be used to replace swellable element technologies in certain environments, such as environments in which temperature and pressure are at the upper limits of or beyond the capabilities of swellable element materials. Similar to a swellable element, the thermally expandable material is able to fully energize the sealing element to create a pressure integral seal without any intervention from the surface. Unlike swellable elements, however, the thermally expandable material 36 serves as a setting mechanism independent of the packer sealing element 32. The combination of thermally expandable material 36 with a high temperature, high pressure sealing element, e.g. a suitable packer sealing element, can be used to provide the functionality of a swellable element but with a substantially increased service life at high temperatures and pressures.
The thermally expandable material 36 and the energized device system 28 may be employed in many high temperature and high pressure applications, including high temperature injector well applications. In certain high temperature injector well applications, a series of packer elements is utilized to segment the well and to improve fluid placement via the injector well. The energized device system 28 may be used in individual or multiple packers deployed in several types of thermal well applications, including steam assisted gravity drainage applications and cyclic steam applications. The thermally expandable material 36 may also be used to actuate other or additional components of packer 42. In some applications, the thermally expandable material 36 may be used in energizing/actuating various other components along the tubing string 22.
Depending on the material and/or environment in which the energized device 30 is employed, the device may have many forms and configurations. The energized device may also utilize various materials and material configurations. In certain embodiments, the thermally expandable material is used singularly to energize a device, while other applications utilize the thermally expandable material as a cooperating or supplemental actuation mechanism. The thermally expandable material may be deployed in individual containers or in a plurality of containers that work in cooperation or serve to actuate different components. Additionally, the thermally expandable material may be in liquid form or other forms and may comprise various individual materials or combinations of materials depending on the parameters of a given application.
Although a few embodiments of the disclosure have been described in detail above, those of ordinary skill in the art will readily appreciate that many modifications are possible without materially departing from the teachings of this disclosure. Accordingly, such modifications are intended to be included within the scope of this disclosure as defined in the claims.
Filing Document | Filing Date | Country | Kind |
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PCT/US12/68934 | 12/11/2012 | WO | 00 |
Number | Date | Country | |
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61570155 | Dec 2011 | US |