BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to the field of oil and gas production, and more particularly, to a rod jack apparatus for installing, removing and servicing oil and gas wells equipped with artificial lift sucker rod assemblies.

2. Description of the Related Art

Most oil wells require a mechanical means to produce. Artificial lift is a process used on oil wells to increase pressure within die reservoir and encourage oil to the surface. The artificial lift system consists of a surface unit and a sucker rod assembly with a positive displacement pump placed at near the bottom of the well. The sucker rod assembly is a series of sucker rods (steel rods that are typically between 25 and 30 feet (seven to nine meters) in length and threaded at both ends) that are joined together to form a single, vertical “string” of rods, the top most of which is referred to as the “polished” rod. As explained in Schlumberger's Oilfield Glossary, the polished rod is “the uppermost joint in the string of sucker rods used in a rod pump artificial-life system. The polished rod enables an efficient hydraulic seal to be made around the reciprocating rod string.” According to Schlumberger, the “rod string” is “an assembled length of sucker rods used to connect and power a rod pump with the reciprocating power source at [the] surface.”

As noted above, the sucker rod assembly is connected to the bottom hole pump, which is seated in a seating profile located at the bottom of the well production tubing. The positive displacement pump is connected to the sucker rod string and either strokes (up/down) or is rotated (depending on pump type) to create a displacement pressure on the tubing and deliver the fluids within the well (oil/gas/water) to the surface. In order to flush fluid/gas down the tubing, the pump must be unseated. Typically, this involves the removal and re-installation of the entire rod assembly at high cost and significant down time before production can resume.

The present invention facilitates a number of different types of well interventions-including well suspensions, shutting down of low production wells, offset well protection, interventions due to low production wells, and well maintenance and repairs—by making it possible to conduct these operations without completely removing the sucker rod assembly. Each of these different types of well interventions is discussed below.

Well suspensions are required for many well operations in which environmental protection is the focus. To properly secure the well, the wellhead must be fully closed, and the well must be inhibited against corrosion. In order to accomplish this task, the downhole pump must be unseated. With the present invention, the downhole pump can be unseated by lifting the rod assembly without fully removing it from the well.

Low production wells are shut in until the economics improve. Current procedures involve the removal of the sucker rod system and the suspension of the well, which is expensive and entails high re-activation costs due to capital cost equipment requirements. This process often results in abandonment of marginally producing wells because of the costs associated with reactivation once the rod assembly has been removed from the well. With the present invention, low production wells can be shut down without removing the entire rod assembly. As a practical matter, removal of the rod assembly for any significant period of time will require complete replacement of the rod assembly.

Offset well protection during oil well completion fracturing operations is a sector of the oil industry that has developed due to reservoir communication during operations.

During infill frack completion operations, offset wells that are affected when communication is achieved during the frack operations require protection from high-pressure communications. Service rig units are deployed to install and setup the wells with high-pressure wellhead systems to prevent any environmental damage, and sucker rod assemblies are pulled or dropped in the well, requiring fishing or high re-installation costs and downtime in order for production to resume. Upon completion of the frack operations, the wellhead assembly must be replaced, the rod assembly must be installed, and the well must be flushed. It takes an average of three days per well for decommissioning and resetting up of the well. The present invention facilitates this process by eliminating the need to remove the entire rod assembly from the well to replace the production wellhead with a high-pressure wellhead or to flush the well with chemicals.

As new well production changes, problems associated with production declines become apparent. These problems include the presence of solids, wax paraffins and sands in the oil stream, as well as scale caused from water production characteristics. Often chemical treatments are used to address these issues, at least temporarily, and service rigs are used to remove the rod assembly from the well to facilitate this process. With the present invention, these chemical treatments can be made without pulling the entire rod assembly out of the well, which greatly reduces the costs associated with the intervention.

Well repairs are an ongoing and routine problem. Production wells are affected by well fluid problems (e g., scale, solids and sand) that require constant maintenance and repairs. Various well head components may require repair, and the polished rod periodically needs to be replaced. Maintenance usually requires that the well be flushed with fluids (chemical treatments) or that the pump be serviced and/or replaced. All of these activities currently require removal of the entire rod assembly from the well, whereas the present invention enables these procedures to be conducted with the sucker rod assembly suspended within the well.

The conventional equipment used to perform well interventions is a mast unit, which consists of a mast (in lieu of a crane or gin pole) and a pulling tool. Mast units typically requires the rental of additional equipment and the use of a four-man crew. Operations using this type of equipment are costly, slow to execute and schedule, and involve the removal of the entire sucker rod assembly from the well. Afler the sucker rod assembly is removed from the Well, the service operation is completed, and the rod assembly is re-installed. An average operation takes about three days to complete. The present invention is a stand-alone unit requires only two people to operate, and significantly reduces the time required to undertake a well intervention.

The oil industry is constantly seeking new technologies and procedures to perform routine maintenance and well intervention work to optimize production. The present invention is a portable system for removing an artificial lift sucker rod assembly that is easy to install, easy to transport, and easy to use. The present invention fundamentally changes the economics of well operations, resulting in reduced operating costs and a more efficient production process. The present invention is structurally distinct from anything in the prior art. The following references are discussed for general background.

U.S. Pat. Nos. 6009941 (Haynes, 2000) and 6209633 (Haynes, 2001) disclose an apparatus for axially displacing a downhole tool or a tubing string a wellbore. The downhole tool is supported by a tubing string with a telescoping joint, the tubing string being situated in the well. A lifting mechanism is connected to a lift rod string, which engages a latch point in the telescoping joint. The apparatus permits the downhole tool to be displaced within a range constrained by the length of the telescoping joint. The apparatus includes a tool entry spool adapted to be mounted to a top of the wellhead and at least one annular seal for containing well pressure that is mounted above the tool entry spool and provides a fluid seal around a periphery of the lift rod string. This apparatus is very different than the present invention in that the present invention straddles the entire wellhead assembly, whereas the Haynes invention is mounted on top of and seals the wellhead.

U.S. Pat. No. 9,702,214 (Turner, 2017) discloses a cap for sealing a wellhead assembly and suspending well assets (e.g., tubing, rods, etc.) within the well from the cap to facilitate production at the well after a period of abandonment. Ends of a tubing string and a rod string disposed within the well are secured within portions of the cap. The cap is placed and secured over the exposed casing head.

U.S. patent Ser. No. 10/138,689 (Gordey et al., 2018) discloses a tool and method for use in supporting a sucker rod string in an oil or gas well driven by an artificial lift. The tool includes a body having a lower narrow portion dimensioned to fit within the interior cavity of a tubing string inlet or an upper extension thereof, an upper wide diameter portion defining a substantially horizontal landing surface dimensioned to rest upon the top edge of the tubing string inlet or the upper extension thereof, one or more sucker rod-engaging structures, and one or more longitudinal slots extending through the lower narrow portion and the upper wide diameter portion to allow passage of fluid or gas through the tool when it is supported on the top edge of the tubing string inlet or the upper extension thereof. The sucker-rod engaging elements may be configured as a longitudinal cavity and slot or as grooves to facilitate clamping of the support tool to the sucker rod, or they may be threaded to receive a sucker rod connector.

BRIEF SUMMARY OF THE INVENTION

The present invention is a rod jack apparatus comprising: two vertical left legs and two vertical right legs configured to form a framework, each of the two vertical left legs and the two vertical right legs having an upper end; a first lower bracket situated horizontally between and connected to the two vertical left legs; a second lower bracket situated horizontally between and connected to the two vertical right legs; a first hydraulic cylinder extending upwardly from the first lower bracket; a second hydraulic cylinder extending upwardly from the second lower bracket; a first horizontal plate; a second horizontal plate; wherein each of the first and second hydraulic cylinders has a top end that passes through an aperture in the first horizontal plate and is fixedly attached to the second horizontal plate; wherein each of the first and second horizontal plates comprises a primary clamping assembly situated on top of the first or second horizontal plate and a secondary clamping assembly situated directly underneath the first or second horizontal plate; wherein the primary clamping assembly comprises a first pair of hydraulic cylinders oriented parallel to each other and situated on a left side of the first or second horizontal plate and a second pair of hydraulic cylinders oriented parallel to each other and situated on a right side of the first or second horizontal plate; wherein each hydraulic cylinder in the first or second pair of hydraulic cylinders on the right or left side of the first or second horizonal plate is mechanically coupled via one or more linkages to a first die having a front surface with a concave section, the first die being configured to clamp around the polished rod when the hydraulic cylinders are extended; and wherein the secondary clamping assembly comprises a C-plate configured to receive a polished rod and at least two hydraulic cylinders arranged radially around a center of the C-plate.

In a preferred embodiment, the invention further comprises: a first upper bracket that is situated horizontally between and connected to the upper ends of the two vertical left legs; and a second upper bracket that is situated horizontally between and connected to the upper ends of the two vertical right legs; wherein the second horizontal plate has left and right ends that are supported by the first and second upper brackets, respectively. Preferably, a second die having a front surface with a concave section is attached to a distal end of a piston rod of each of the at least two hydraulic cylinders of the secondary clamping assembly. Each of the first and second horizontal plates preferably comprises: a central channel that extends from a front to a center of the first or second horizontal plate; and a front recess that spans the central channel and is configured to receive a removable bracket.

In a preferred embodiment, the invention further comprises a first platform situated directly on top of the first horizontal plate and a second platform situated directly on top of the second horizontal plate; wherein each of the first and second platforms is configured to move from a first position relative to the first or second horizontal plate to a second position relative to the first or second horizontal plate; wherein when the platform is in the second position, the platform is closer to the polished rod than when the platform is in the first position; wherein each first die resides within a die housing; wherein the one or more linkages are configured so that the first die and die housing tilt forward toward the polished rod and the platform moves from the first position to the second position when the primary clamping assembly is activated; and wherein a first spring pushes the platform back to the first position when the primary clamping mechanism is inactivated. Preferably, the concave section on the front surface of the first die has a first radius and a second radius, and the first radius is greater than the second radius. Preferably, the concave section on the front surface of the first die comprises: a plurality of parallel grooves extending laterally across an inside surface of the concave section; and two parallel grooves extending longitudinally from a bottom of the first die to a top of the first die along the inside surface of the concave section.

In a preferred embodiment, the invention further comprises a second spring that is situated inside the die housing and configured to bias the first die in an upward position when the first die is inserted into the die housing. Preferably, the first die comprises a rear wall; wherein the front surface of the first die comprises a flat section on either side of the concave section; and wherein the rear wall of the first die is at an eighteen-degree angle relative to the flat section of the front surface of the first die. The die housing preferably comprises a first lip along a right front edge of the die housing and a second lip along a left front edge of the die housing; each of the first and second lips extending inward to form a channel; wherein the first die comprises right and left rear wings; wherein the first and second lips on the die housing and configured to receive the right and left rear wings on the first die; wherein the die housing further comprises a bottom beveled edge; and wherein the first and second lips are shorter than the right and left wings so as to form a gap between a bottom end of each of the first and second lips and the bottom beveled edge of the die housing.

The present invention is also a method of lifting a sucker rod assembly from a wellbore comprising the steps of: installing the rod jack apparatus of claim1over a wellbore; activating the primary clamping assembly on the second horizontal plate; activating the secondary clamping assembly on the second horizontal plate; extending the first and second hydraulic cylinders; activating the primary clamping assembly on the first horizontal plate; activating the secondary clamping assembly on the first horizontal plate; releasing the primary and secondary clamping assemblies on the second horizontal plate; retracting the first and second hydraulic cylinders; repeating steps (b) and (c); releasing the primary and secondary clamping assemblies of the first horizontal plate; and repeating steps (d) through (h).

