Patent ID: 12215583

DETAILED DESCRIPTION

In the following discussion, numerous specific details are set forth to provide a thorough understanding of the present disclosure. However, it will be obvious to those skilled in the art that embodiments of the present disclosure can be practiced without such specific details. Additionally, for the most part, details concerning well drilling, reservoir testing, well completion and the like have been omitted inasmuch as such details are not considered necessary to obtain a complete understanding of the present disclosure, and are considered to be within the level of skill of persons having ordinary skill in the relevant art.

The present disclosure relates to blanking plugs used in conjunction with electrical submersible pumps used in hydrocarbon development operations. More specifically, the disclosure relates to blanking plugs with improved capability to minimize problems in well intervention operations caused by accumulation of sand and other solids on top of blanking plugs.

As will be made clear in the following detailed description of the embodiments of the present disclosure, at least one of the following advantages and benefits may be provided or achieved: prevention or minimization of sand and scale accumulation on top of the ESP blanking plug; elimination or reduction of the need for high cost sand/scale fill removal operations; provision of wellbore accessibility for vital well intervention operations; provision of simplified sand/scale sample collection for subsequent lab analysis thus improved scale mitigation planning; protection of ESP integrity and prolonged ESP run life; prevention of sand accumulation around the ESP shaft; reduction of ESP failures due to sand/scale accumulation; minimization of additional pressure drop during oil well startup operations.

An embodiment of the disclosure incorporates a customized wireline assembly above an ESP blanking plug body that can be utilized to filter sand and scale particles thus allowing only the fluid phase to pass thus preventing any solid accumulation on top of the plug.

As illustrated schematically inFIG.1, an oil well10generally provides for extraction of petroleum and other wellbore fluids from a formation11in the earth and transport of such fluids to the surface12of the well10. The well10can an offshore well or a land-based well and can be used for producing hydrocarbons from subterranean hydrocarbon reservoirs.

In construction of the well10, production tubing string13is positioned within the casing14of the well10. In an embodiment of this disclosure, a system for providing artificial lift to wellbore fluids includes a pump15, which is an electrically submersible pump (ESP), submerged in wellbore fluids and in fluid communication with the tubing string13extending within the wellbore. The ESP15can be, for example, a rotary pump such as a centrifugal pump. The ESP15could alternatively be a progressing cavity pump, which has a helical rotor that rotates within an elastomeric stator or other type of pump known in the art for use in an ESP.

The ESP is oriented to selectively boost a pressure of the wellbore fluids traveling from the formation11of the well10towards the earth's surface12, as is well known and conventional in the art, so that wellbore fluids can travel more efficiently to the earth's surface12.

During production operations, access to the formation11from the surface12is occasionally required. In order to avoid the necessity of withdrawing the ESP from the tubing13each time such access is necessary, the ESP is positioned in a Y-tool16adjacent to, outside of, and in fluid communication with the tubing string13, as is known in the relevant art. In order to prevent recirculation of fluids lifted by the ESP15back down the tubing13, a blanking plug17is positioned in the tubing13adjacent and between the upper and lower passages or connections16a,16b, respectively, of the Y-tool16to the tubing string13. While tubing string13is schematically illustrated as being vertical inFIG.1, it will be understood by persons having ordinary skill in the art that the tubing string13may have an orientation other than vertical; thus, the terms “upper” and “lower” in the description of this embodiment are intended to signify relative positions rather than physical directions. More particularly, the “upper” Y-tool connection16ato the tubing13is simply the connection closer to the surface12of the well10, and the “lower” Y-tool connection16bis closer to the distal end of the tubing string13located in the formation11.

Further during production operations, the ESP lifts fluids in a flow direction18and path from the formation11through the tubing13, into the Y-tool16via the lower connection16b, through the ESP15, out the Y-tool16via the upper connection16aback into the tubing string13and to the surface12of the well10. In addition to desirable fluids, however, sand which may be silica (SiO2), calcium carbonate (CaCO3), calcium sulfate (CaSO4), strontium sulfate (SrSO4), dolomite (CaMg(CO3)2), and other corrosion products are also entrained in the fluids and are also lifted by and through the ESP15. Upon reentry of the fluids via the upper Y-tool connection16ainto the tubing13above or past the blanking plug17, such sand18and other particulates tend to settle on top of the blanking plug17.

If not addressed in some way, such as by embodiments of the present disclosure, sand18may accumulate to such a degree and amount that retrieval of the blanking plug17is very difficult or, in extreme cases, nearly impossible. In addition, accumulation of sand18on top of the blanking plug17may cause sand and scale to also accumulate within the ESP15and, more particularly, around the shaft of the pumping mechanism within the ESP15, which may reduce ESP run life and integrity and, consequently, lead to premature pump failures.

Referring now toFIG.2, an embodiment of an improved blanking plug20for use in association with an ESP15as shown in the well environment illustrated inFIG.1. At the downhole end of the plug20is a flow isolation mechanism21. Flow isolation mechanism21prevents downhole recirculation of lifted fluids across the Y-tool16. A positioning structure such as a no-go shoulder22is provided to fit closely and stop downhole movement of the blanking plug20at a complimentary nipple or profile of the inside wall of the tubing string13. A series of circumferentially positioned shear pins23is provided, the function of which will become clear in connection with further features now described.

At least one locking device is provided to hold the blanking plug20at a desired first working position in the tubing13. In an embodiment, the locking device, which may also serve as a positioning structure, comprises a set of radially extending locking dogs24which, when extended, hold the blanking plug20at a desired position. The locking dogs24are activated and radially extended by operation of the shear pins23in conventional fashion. The embodiments of the present disclosure are not limited to the disclosed anchoring or positioning components or assemblies. Instead, other types of anchoring mechanisms, including those that, for example, do not require a complimentary profile or nipple within the tubing string and those that might anchor within a tubing string using slips, packers, or other means known in the art for securing a tool within a conduit, may be employed.

Circumferential elastomeric seals25, such as elastomeric O-rings, provide additional fluid sealing between the surface and downhole ends of the plug20, and consequently between the upper and lower Y-tool connections16a,16b. A pressure equalization port26located proximate the upper end of the blanking plug20is connected to an internal pressure equalization passage extending within the blanking plug20from the port26to an opening in the flow isolation mechanism21. When opened by activation of the shear pins23, the port provides pressure equalization below and above the plug20.

Specifically, the blanking plug device has an anchoring portion for securing the blanking plug device within a tubing string or other well conduit. The blanking plug device may be used for blanking off all pressure from above or below the device in connection with pressure testing the tubing string or to abandon certain zones within a well. The blanking plug may include a no-go shoulder, radially expandable locking dogs, pressure equalization ports, and annular seals, among other conventional features of blanking plugs. Further or more specific detail of these features is not necessary for a complete disclosure and understanding of the embodiments of the present disclosure, as component parts of the blanking plug thus far described are conventional and known to those of ordinary skill in the art.

Referring again toFIG.2of the present disclosure, a sand trap29with mesh filter27is provided at the upper end of the blanking plug20. As sand and other particulates are lifted by the ESP15and flow upward to the surface12of the well10, the sand and particulates will settle into a particulate accumulation chamber in the trap29for subsequent collection, disposal, and optionally laboratory testing. A standard internal fishing neck28designed to be latched by a conventional GS style pulling tool is provided above the sand trap29. While a GS style fishing neck is illustrated, any other wireline or slickline pulling tool and corresponding on-device connector structure may be employed.

During production operations, after a certain time has passed, a well operator will briefly pause production operations for the purpose of removing the accumulated sand18and other particulates within the sand trap29on top of the blanking plug20. Referring toFIG.3, an embodiment of a method of using a blanking plug of the present disclosure is illustrated in flowchart format. While the method steps are illustrated in a particular order, it will be understood that some of the steps may be performed in different sequences than as is illustrated.

According to the embodiment ofFIG.3, a method of producing fluids from a fluid-producing formation11in the earth is shown. A wellbore is drilled from a surface12of the earth to a fluid-producing formation11in the earth (STEP310) in any conventional manner. Likewise, in any conventional manner wellbore casing14is installed (STEP320) followed by installation of a production tubing string13(STEP330) extending into the fluid-producing zone11of the formation. An annular space is provided between the tubing string13and the wellbore casing14in known fashion.

A Y-tool16having upper and lower connections16a,16bto the tubing string13is provided in the annular space (STEP340) and a pump15, which may be an ESP, is installed in the Y-tool16(STEP350). These steps may be performed in any desired and convenient order, for example, by first providing a subassembly comprising a section of production tubing having an ESP-fitted Y-tool connected thereto, and then incorporating such subassembly into the tubing string during installation of the tubing string.

A blanking plug20having a sand trap29at its upper end according to an embodiment of the present disclosure is next run downhole via wireline or any other suitable manner, to a working position located between the upper and lower connections16a,16bof the Y-tool16(STEP360). Fluids are then pumped by the ESP15via the Y-tool16from the fluid-producing formation11to the surface12of the well10(STEP370).

After a period of pumping fluids, pumping operation of the ESP15is suspended. A GS style or any other appropriate pulling tool is run downhole to mate with and attach to the fishing neck28of the blanking plug20. The locking dogs24are moved radially inwardly thereby unlocking the blanking plug20from its working position. The blanking plug20is then withdrawn from the tubing string13, and the sand trap29is emptied of accumulated particulates (STEP380). Next, the blanking plug20in returned to its downhole position adjacent the Y-tool16and pumping operations are resumed (STEP390). After another period of pumping, the blanking plug20is again retrieved for emptying of the sand trap29(STEP380).

During retrieval of the blanking plug20from the tubing string13, the mesh filter27positioned in the wall of the particulate accumulation chamber of the sand trap29allows fluids to pass through the sand trap29while trapping additional sand and scale present or suspended in the fluid column extending from the Y-tool16to the surface12of the well10.

The appropriate size of openings of the mesh filter27will depend on the nature of the sand, scale, and other particulate matter in a given fluid produced by a particular well. In addition, the size of the sand trap will depend on the accumulation rate of settling solid particles, which may in turn depend on the flow rate and volume, as well as viscosity, of the fluid being lifted by the ESP. Using this information, accurate estimation of the appropriate time interval between successive retrievals of the blanking plug for disposal of the collected sand and scale is easily done, with a goal of avoiding over-filling of the sand trap. As is conventional in the art, the appropriate size of wireline cable that can withstand the combined weight of the blanking plug including the mesh filter and accumulated sand is selected.

Although only a few exemplary embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the example embodiments without materially departing from this invention. Accordingly, all such modifications are intended to be included within the scope of this disclosure as defined in the following claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures. It is the express intention of the applicant not to invoke 35 U.S.C. § 112(f) for any limitations of any of the claims herein, except for those in which the claim expressly uses the words ‘means for’ together with an associated function.