Patent Application
20160090815
In the oilfield it has become common practice to drill a well that intersects numerous formations or portions of formations. Sometimes the well may be primarily vertical and sometimes the well may have a significant horizontal section. Once the wellbore has been drilled it is usually necessary to case the well. In the past the casing was typically a number of joints of solid pipe joined together and then run into the wellbore. Once the casing had been located in the wellbore it was then cemented in place by forcing cement through the interior of the pipe, out of the toe of the pipe, and back up around the annular area formed between the casing and the wellbore itself.
With the casing cemented in the well the interior of the pipe casing was effectively sealed from allowing any fluids to flow from the formations to the interior. With the casing effectively sealed against fluid flow it is then necessary to provide a means to access the exterior of the casing and reestablish fluid flow upon demand. Typically the casing is perforated or a ported sleeve is used to reestablish fluid flow with the exterior the casing. The ported sleeve is commonly referred to as a toe sleeve. Because positive fluid flow through the casing is limited at best without access to the exterior of the casing, it is difficult to pump a ball or a dart through the casing to actuate the toe sleeve. Therefore toe sleeve actuation is limited to pressure actuation or mechanical manipulation from the surface such as the use of slick line or electric line. Today many toe sleeves are actuated by pressure. Unfortunately there may be other requirements to pressurize the casing prior to actuating the toe sleeve. For instance it may be necessary to check the integrity of the casing and the cement holding the casing in place by performing a pressure test on the casing. In such instances it is not uncommon to pressurize the casing to 10,000 psi or more. Any toe sleeve actuation greater than the pressure test creates uncertainty as to whether the toe sleeve actuated or the casing failed.
In order to overcome at least the aforementioned issue an embodiment of the present invention allows for the casing to be pressurized and depressurized a predetermined number of times prior to actuating the toe sleeve. Additionally each pressurization cycle may be well in excess of the amount of pressure that it takes to open the toe sleeve on the toe sleeve actuation cycle.
More specifically in this embodiment the toe sleeve has an inner sleeve with a first and second total piston area. The inner sleeve also has a first, second, and third longitudinal position. Additionally the inner sleeve has rotary indexing device such as an indexing j-slot profile formed on the exterior surface of the inner sleeve. The final portion of the j-slot profile extends a sufficient longitudinal distance to allow the inner sleeve to move to a point where interior fluid pressure may reach the second piston area. The toe sleeve has a bottom sub, a top sub, and a ported sub where the ported sub is disposed around the inner sleeve. In many instances the bottom sub, top sub, or ported sub may be combined into single assemblies. A lug may be positioned in the ported sub where the lug engages the indexing j-slot of the inner sleeve piston. In certain instances the lug may be incorporated into the inner sleeve while the j-slots may be incorporated into a housing or other exterior subassembly. The housing is disposed around the inner sleeve piston and bottom sub. In many instances different combinations of the bottom sub, top sub, ported sub and housing may be combined into single assemblies. The toe sleeve has an atmospheric chamber formed by the housing, the inner sleeve, and the bottom sub. The toe sleeve also has a spring chamber in the housing between the inner sleeve and the housing. A biasing device such as a spring, pressurized chamber, or other means to store energy resides in the spring chamber to provide a return force to the inner sleeve in the absence of pressure against the first piston area on the sleeve.
When pressure is applied from the surface to the inner sleeve piston. The inner sleeve moves from its first position to a second position as provided for by the lug travelling in the indexing j-slot of the inner sleeve. When the inner sleeve moves from a first position to a second position the inner sleeve moves longitudinally in the housing it also rotates some slight amount. As pressure from the surface is relieved the biasing device shifts the inner sleeve longitudinally in the opposite direction and the inner sleeve again rotates some small amount. While the longitudinal movement of the inner sleeve is back and forth, the rotational movement is all in a single direction. Shoulders on the ported sub as well as the lug or lugs, if more than one j-slot is used to provide a backstop preventing the inner sleeve from damaging the lug or lugs in the instance that very high pressure is exerted against the interior piston of the inner sleeve.
When a pre-determined number of pressure cycles occur the inner sleeve is rotated so that the lug travels to a longer slot profile of the indexing j-slot profile so that inner sleeve is allowed to move to the third position. As the inner sleeve moves through the longer slot profile a seal is eliminated and the second piston area of the inner sleeve is exposed. Upon exposure of the second piston area, the total piston area reverses and thus the force due to fluid pressure from the interior of the toe sleeve and acting upon the inner sleeve aligns with the biasing device and now works to move the inner sleeve and open the ports. The piston force acting on the second piston area causes the inner sleeve to move into the atmospheric chamber and shoulders the inner sleeve piston against the bottom sub. Opening the plurality of ports in the ported sub allows the fluid in the tubing/casing string to exit the tubing/casing string and make contact with the formation.
The description that follows includes exemplary apparatus, methods, techniques, or instruction sequences that embody techniques of the inventive subject matter. However, it is understood that the described embodiments may be practiced without these specific details.
The ported sub 108 has at least one port 136. In the event that inner sleeve 112 should slide downward a sufficient amount the inner sleeve 112 will uncover port 136 to allow fluid flow through port 136 from the interior 166 of the toe sleeve 100 to the exterior of the toe sleeve 100. The ported sub 108 also has at least one shear pin 138 shear pin 138 extends through the ported sub 108 and into a recess 140 cut in the exterior of the inner sleeve 112. The shear pin 138 when engaged with recess 140 and the inner sleeve 112 prevents the inner sleeve 112 from moving in relation to the ported sub 108. Any motion that might prematurely cause the inner sleeve 112 to cycle is not desired. Such operations may include running the casing that includes the toe sleeve 100 into the well and flowing cement through the interior of the tubular including the toe sleeve 100. However upon the application of sufficient fluid pressure through the interior of the tubular and thus the interior 166 of the toe sleeve 100, pressure is exerted against first piston 132 and second piston 134. The areas of piston 132 and 134 together form a first piston area and are calculated so that the area of piston 132 is greater than the area piston 134 so that the applied pressure will cause the inner sleeve to move upward within the housing 102 initially shearing the shear pin 138. A lug 142 in the ported sub 108 extends into a slot 146 that is been cut into the exterior circumferential surface of inner sleeve 112. A shoulder 135 on the ported sub 108 may engage the second piston 134 of inner sleeve 112 as the inner sleeve moves upward during a pressure cycle.
As pressure is relieved in the interior 166 of the toe sleeve 100, the biasing device 144 overcomes the force exerted upon the toe sleeve 100 through pistons 132 and 134 and exerts force against the third piston 130. As inner sleeve 112 moves downward the lug 142 moves from the second position 152 to the third position 154 as indicated by arrow 164. During the next pressure cycle as pressure is again exerted against piston surfaces 132 and 134 the inner sleeve 112 again moves upward causing the lug 142 to move from the third position 154 to the fourth position 156 as indicated by arrow 168. As pressure is once again relieved in the interior 166 of the toe sleeve 100, the biasing device 144 overcomes the force is exerted upon the toe sleeve 100 through pistons 132 and 134 and exerts pressure against the third piston 130 moving the inner sleeve 112 downward. As inner sleeve 112 moves downward the lug 142 moves from the fourth position 156 to the fifth position 158 as indicated by arrow 170. The inner sleeve 112 moves downward towards the fifth position, in this case the fifth position is displaced a sufficient distance to allow the inner sleeve 112 to move past the seals and allow fluid pressure to access the area circumferentially outward from the inner sleeve 112 and towards the ports 136. In the fifth position the second piston area is accessed by the pressurized fluid in the interior 166 of the inner sleeve 112. The second piston area is the combination of the second piston 134 and the third piston 130 less the area of the first piston 132 in combination with the force acting against each due to the pressure of the fluid in the toe sleeve 100. The total force exerted against the piston faces acts to move the inner sleeve 112 downward. Once fluid pressure can move radially outward of the inner sleeve 112 the fluid can reach piston 130 thereby forcing a portion of the inner sleeve 112 into the first chamber 114 thereby allowing full access for fluid to flow from the interior 166 of the toe sleeve 100 to the exterior of the toe sleeve 100 through port 136.
While the embodiments are described with reference to various implementations and exploitations, it will be understood that these embodiments are illustrative and that the scope of the inventive subject matter is not limited to them. Many variations, modifications, additions and improvements are possible.
Plural instances may be provided for components, operations or structures described herein as a single instance. In general, structures and functionality presented as separate components in the exemplary configurations may be implemented as a combined structure or component. Similarly, structures and functionality presented as a single component may be implemented as separate components. These and other variations, modifications, additions, and improvements may fall within the scope of the inventive subject matter.
