Downhole cleaning tools and methods for operating the same

A downhole tool assembly includes a housing, the housing defining one or more formation jetting ports structurally configured to pass fluid outward from the downhole tool assembly, a downhole motor positioned at least partially within the housing, a centrifugal pump coupled to the downhole motor, the centrifugal pump including a shaft coupled to the downhole motor, and one or more blades extending outward from the shaft, and a filtration element in communication with the centrifugal pump, where the filtration element is structurally configured to separate particulate matter from fluid passing through the filtration element.

BACKGROUND

Field

The present disclosure relates to downhole cleaning tools and methods for operating the same.

Technical Background

Wellbores may be drilled into the ground to extract petroleum in the form of fluids and/or gases. During the drilling process, drilling fluid may be utilized to assist with the drilling of the wellbore. The drilling fluid may include fine particulate matter that invades ground surrounding the wellbore, thereby reducing the permeability of the ground surrounding the wellbore. The reduced permeability may negatively impact the productivity of the wellbore.

BRIEF SUMMARY

Accordingly, it is desirable to mitigate the reduced permeability of the ground surrounding the wellbore as the result of the invasion of the drilling fluid and/or as the result of other mechanisms that can result in reduced permeability of the ground surrounding the wellbore. Some configurations include passing fluid from the wellbore up to the surface and filtering and/or treating the fluid at the surface. However, passing fluid to the surface can be time consuming and costly, particularly in deep wellbores or offshore wellbores.

Embodiments of the present disclosure are generally directed to downhole tool assemblies that filter fluid in place within a wellbore. By filtering fluid in place within the wellbore, the time and cost associated with increasing the permeability of ground surrounding the wellbore may be reduced as compared to configurations in which the fluid is passed to the surface.

In one embodiment, a downhole tool assembly includes a housing, the housing defining one or more formation jetting ports structurally configured to pass fluid outward from the downhole tool assembly, a downhole motor positioned at least partially within the housing, a centrifugal pump coupled to the downhole motor, the centrifugal pump including a shaft coupled to the downhole motor, and one or more blades extending outward from the shaft, and a filtration element in communication with the centrifugal pump, where the filtration element is structurally configured to separate particulate matter from fluid passing through the filtration element.

In another embodiment, a downhole tool assembly including a housing including an inner sidewall defining an inner cavity, and an outer sidewall positioned outward of the inner sidewall where the inner sidewall and the outer sidewall define a fluid channel positioned between the inner sidewall and the outer sidewall, a downhole motor positioned at least partially within the inner cavity of the inner sidewall, and a centrifugal pump coupled to the downhole motor.

In yet another embodiment, a method for cleaning a wellbore includes drawing a fluid into a housing of a downhole tool assembly, the housing defining an inner cavity, passing the fluid to a centrifugal pump, the centrifugal pump including a shaft and one or more blades extending outward from the shaft, rotating the shaft and the one or more blades of the centrifugal pump, thereby drawing the fluid through the centrifugal pump, and passing the fluid from the centrifugal pump out a formation jetting port of the housing.

Additional features and advantages of the technology disclosed in this disclosure will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from the description or recognized by practicing the technology as described in this disclosure, including the detailed description which follows, the claims, as well as the appended drawings.

Reference will now be made in greater detail to various embodiments, some embodiments of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or similar parts.

DETAILED DESCRIPTION

Embodiments of the present disclosure are directed to downhole tool assemblies that may be utilized to mitigate formation damage by “cleaning” wellbores. The downhole tool assemblies generally include a housing and a downhole motor. In some embodiments, a centrifugal pump is coupled to the downhole motor, and a filtration element is in communication with the centrifugal pump. The centrifugal pump and/or the filtration element may remove particulate matter from formation fluid drawn through the downhole tool assembly. By removing particulate matter from the formation fluid, the downhole tool assemblies may mitigate formation damage that may result from drilling processes. In some embodiments, the downhole tool assemblies may be operable to pass an acid wash or the like to the wellbore to mitigate formation damage. These and other embodiments will now be described with reference to the appended drawings.

Now referring toFIG.1, a section view of a wellbore10defining a well wall12is schematically depicted. The wellbore10generally extends from an opening11below a surface30, which may be a ground surface (i.e., in land-based wellbores10) or may be the floor of a body of water (i.e., in offshore wellbores10). Gases and/or fluids, such as petroleum products, may be extracted through the wellbore10. While inFIG.1the wellbore10is depicted as having a generally vertical orientation, it should be understood that this is merely illustrative, and wellbores10according to the present disclosure may extend in any suitable direction below the surface30. For example, wellbores10may extend at least partially in a horizontal direction and/or may include portions that extend in the horizontal direction.

The wellbore10may be formed by a drill (e.g., a drill string), and drilling fluids (i.e., drilling mud) may be utilized to aid the drilling of the wellbore10. The drilling fluid may cause formation damage in the wellbore10, reducing the permeability of ground16surrounding the wellbore10. For example, drilling fluid may include fine particles referred to as “fines” that may invade the surrounding ground16. As the fines invade the surrounding ground16, the permeability of the surrounding ground16generally decreases, thereby restricting the flow of fluid (e.g., formation fluid and/or reservoir fluid) from the surrounding ground16to the wellbore10. Formation damage may also occur via other mechanisms, such as fines migration (e.g., the movement of naturally existing fine particles into the pore system of the surrounding ground16) or phase trapping and blocking (e.g., the reduction in water saturation caused by the invasion of fluids from the wellbore10to the surrounding ground16). Formation damage may also occur via glazing and mashing (e.g., damage to the well wall12by a drill bit or rotating drill string), perforation damage (e.g., damage associated with perforation gun charges fracturing rock into fine grains that degrade the permeability of the surrounding ground16), and/or proppant crushing and embedment (e.g., damage associated with hydraulic fracturing). The restriction of the flow of fluid to the wellbore10may negatively impact the productivity of the wellbore10, and accordingly it is desirable to reduce formation damage.

To reduce the formation damage (i.e., to increase the permeability of the surrounding ground16), fluids from the surrounding ground16may be filtered to remove particulate matter. By filtering fluids from the surrounding ground16, the permeability of the surrounding ground16may be increased, thereby reducing the formation damage and increasing the productivity of the wellbore10.

Referring toFIG.2, a downhole tool assembly100is depicted within the wellbore10. In embodiments, the downhole tool assembly100may be positioned on string102extending into the wellbore10. While the embodiment depicted inFIG.2shows the string102, it should be understood that this is merely an example, and the downhole tool assembly100may be positioned on any suitable device, such as a wireline, coil tubing, or may be part of a completion accessory. In embodiments, the downhole tool assembly100may be removable from the wellbore10, or may be part of permanent downhole completion design.

The string102may extend between the downhole tool assembly100to the opening11(FIG.1) of the wellbore10. In some embodiments, the string102may be in fluid communication with the downhole tool assembly100, such that fluids can be passed along the string102to the downhole tool assembly100. As described in greater detail herein, solutions such as an acid wash, solvents, or the like may be passed along the string102to the downhole tool assembly100to the downhole tool assembly100to assist with treating the wellbore10(e.g., via matrix stimulation), in some embodiments.

In embodiments, the downhole tool assembly100generally includes a housing110, a downhole motor130positioned at least partially within the housing110, a centrifugal pump140coupled to the downhole motor130, and a filtration element146in communication with the centrifugal pump140. While the housing110is depicted as having a generally cylindrical shape and positioning of certain components are described herein in relation to “radial” and “circumferential” directions, it should be understood that this is merely an example, and the housing110may have any suitable shape. For example, in embodiments, the housing110may have a polygonal prism shape or the like.

In some embodiments, the housing110defines one or more circulation ports120. Fluid surrounding the downhole tool assembly100may enter into the housing110through the one or more circulation ports120. The housing110, in some embodiments, includes one or more formation jetting ports116structurally configured to pass fluid outward from the downhole tool assembly100. Filtered fluid from the downhole tool assembly100may be passed out of the housing110through the one or more formation jetting ports116, as described in greater detail herein.

In some embodiments, the downhole tool assembly100may include one or more packer assemblies160engaged with an outer surface of the housing110. For example, in the embodiment depicted inFIG.2, the downhole tool assembly100includes an upstream packer assembly160and a downstream packer assembly162. As referred to herein, the term “downstream” refers to the relative positioning of components of the downhole tool assembly100in a direction22extending away from the opening11(FIG.1) of the wellbore10. The term “upstream” refers to the relative positioning of components extending in a direction20toward the opening11(FIG.1) of the wellbore10and is opposite the direction22. While the directions20,22are depicted as extending in the vertical direction, it should be understood that this is merely an example. In some embodiments, the upstream packer assembly160is positioned upstream of the one or more formation jetting ports116and/or the one or more circulation ports120. In some embodiments, the downstream packer assembly162may be positioned downstream of some or all of the one or more formation jetting ports116and/or the one or more circulation ports120.

In embodiments, the upstream packer assembly160and the downstream packer assembly162may engage the well wall12(FIG.1) and the housing110of the downhole tool assembly100. By engaging the well wall12(FIG.1) and the housing110, the upstream packer assembly160and/or the downstream packer assembly162may restrict the flow of fluid between the well wall12(FIG.1) and the housing110. As such, the upstream packer assembly160and/or the downstream packer assembly162may at least partially seal the one or more formation jetting ports116and/or the one or more circulation ports120from areas of the wellbore10spaced apart from the downhole tool assembly100.

In embodiments, the downhole motor130is structurally configured to rotate the centrifugal pump140. The downhole motor130may include any suitable motor for rotating a centrifugal pump140positioned in a wellbore10, and may include, for example and without limitation, a hydraulic motor or the like. In embodiments, the downhole motor130may be selectively activated in any suitable manner, for example and without limitation, a drop ball or the like.

Referring toFIG.3A, a section view of the downhole tool assembly100is schematically depicted. In some embodiments, the housing110includes an inner sidewall112and an outer sidewall114. The inner sidewall112, in embodiments, is positioned inward (e.g., in a radial direction) of the outer sidewall114.

In embodiments, the housing110defines an inner cavity122. The centrifugal pump140and the filtration element146, and/or the downhole motor130are positioned at least partially within the inner cavity122. In some embodiments, the inner sidewall112defines the inner cavity122and the inner cavity122is positioned inward of the inner sidewall112(e.g., in a radial direction).

In some embodiments, the inner sidewall112and the outer sidewall114define one or more fluid channels124positioned between the inner sidewall112and the outer sidewall114. The one or more fluid channels124, in some embodiments, are in communication with the inner cavity122, such that fluid can flow from the inner cavity122to the one or more fluid channels124. For example, in some embodiments, the centrifugal pump140may move fluid from the inner cavity122to the one or more fluid channels124, as described in greater detail herein.

In embodiments, the housing110defines the one or more formation jetting ports116. For example, in the embodiment depicted inFIG.3A, the outer sidewall114defines the one or more formation jetting ports116. Fluid may be passed, in some embodiments, from the inner cavity122, through the one or more fluid channels124, and out the one or more formation jetting ports116. In some embodiments, fluid, such as an acid wash, can be passed to the one or more formation jetting ports116from the string102(FIG.2).

Referring toFIGS.3A and3B, a top section view of the housing110is schematically depicted. In some embodiments, the one or more formation jetting ports116are spaced apart from the one or more circulation ports120in a circumferential direction. In embodiments, the one or more circulation ports120extend through the inner sidewall112and the outer sidewall114, such that the one or more circulation ports120are in communication with the inner cavity122and fluid can be drawn from outside of the housing110to the inner cavity122through the one or more circulation ports120.

In embodiments, the centrifugal pump140extends between a pump inlet150and a pump outlet152. The centrifugal pump140, in embodiments, includes a shaft142and one or more blades144extending outward from the shaft142. In some embodiments, the centrifugal pump140may include one or more stators148. In embodiments the one or more stators148may be positioned between the one or more blades144. In the embodiment depicted inFIG.3A, the one or more stators148extend inward from the inner sidewall112.

The shaft142, in embodiments, is coupled to the downhole motor130. In some embodiments, the downhole tool assembly100may include one or more seals132positioned between the downhole motor130and the one or more blades144of the centrifugal pump140. The one or more seals132may engage the shaft142, restricting the flow of fluid from the centrifugal pump140to the downhole motor130.

The downhole motor130may rotate the shaft142, which thereby rotates the one or more blades144. As the one or more blades144rotate, the one or more blades144may draw fluid through the centrifugal pump140. For example, in some embodiments, the one or more blades144may be arranged helically along the shaft142, such that the one or more blades144may draw fluid through the centrifugal pump140from the pump inlet150to the pump outlet152.

Further, as the one or more blades144rotate, particulate matter within fluid passing through the centrifugal pump140from the pump inlet150to the pump outlet152may move radially outward as the result of centrifugal force applied to the fluid. In some embodiments, as the one or more blades144rotate, particulate matter may be passed to the one or more stators148, which may retain at least a portion of the particulate matter, such that fluid exiting the pump outlet152has less particulate matter than fluid entering the pump inlet150. In this way, the centrifugal pump140may act as a centrifugal separator, thereby assisting in removing particulate matter from fluid.

The filtration element146, in embodiments, is in communication with the centrifugal pump140, and is structurally configured to separate particulate matter from fluid passing through the filtration element146. For example, fluid may pass to the filtration element146from the one or more circulation ports120, through the filtration element146, to the pump inlet150. As the fluid passes through the filtration element146, particulate matter in the fluid may be restricted from flowing through the filtration element146, such that fluid passing from the filtration element146to the pump inlet150may have less particulate matter than fluid entering the filtration element146. The filtration element146, in embodiments, may include any suitable medium or mediums for restricting the flow of particulate matter.

Methods for operating the downhole tool assembly100to clean the wellbore10will now be described.

Referring toFIGS.3A and4, an example flowchart for one method of operating the downhole tool assembly100is depicted. In a first block402, fluid is drawn into the housing110. For example and as described above, in embodiments, fluid (e.g., formation fluid and/or reservoir fluid) from the wellbore10(FIG.1) and/or surrounding ground16(FIG.1) may be drawn into the housing110through the one or more circulation ports120.

In a second block404, the fluid passed to the centrifugal pump140. For example, as the fluid is drawn into the housing110, the fluid may be passed through the inner cavity122to the centrifugal pump140. In embodiments, the fluid may be drawn to the centrifugal pump140as a result of the movement of the centrifugal pump140(e.g., via the rotation of the one or more blades144of the centrifugal pump140).

In embodiments in which the downhole tool assembly100includes the filtration element146, the fluid may pass through the filtration element146as the fluid moves through the inner cavity122to the centrifugal pump140. As described above, as the fluid moves through the filtration element146, particulate matter within the fluid may be restricted from passing through the filtration element146.

In a third block406, the fluid is drawn through the centrifugal pump140via rotation of the one or more blades144of the centrifugal pump140. As described above, the one or more blades144of the centrifugal pump140may be rotated as the downhole motor130rotates the shaft142of the centrifugal pump140. As described above, as fluid passes through the centrifugal pump140, particulate matter within the fluid may be separated from the fluid, for example as the result of centrifugal forces acting on the fluid. Accordingly, fluid passing out of the centrifugal pump140may generally have less particulate matter than fluid passing into the centrifugal pump140.

In a fourth block408, the fluid is passed from the centrifugal pump140, out of the one or more formation jetting ports116of the housing110. For example, in embodiments, fluid from the centrifugal pump140is passed through the one or more fluid channels124to the one or more formation jetting ports116, and thereby out of the downhole tool assembly100.

In this way, particulate matter within fluid (e.g., formation fluid and/or reservoir fluid) in the wellbore10(FIG.1) can be removed, thereby reducing formation damage and increasing the permeability of surrounding ground16(FIG.1). As noted above, in some embodiments, fluid, such as an acid wash, can also be passed to the one or more formation jetting ports116from the string102(FIG.2) to reduce formation damage.

By reducing formation damage with the downhole tool assembly100, the time and cost associated with reducing formation damage can be reduced as compared to conventional methods. For example, in some conventional configurations, formation fluid and/or reservoir fluid may be passed to the surface30(FIG.1) for treatment/filtration, and may then be returned back to the wellbore. However, the time and energy required to move fluid from a downhole position within the wellbore10to the surface30(FIG.1) may be significant, particularly in deep wellbores10and/or offshore wellbores10. By treating/filtering formation fluid and/or reservoir fluid in place in the wellbore10with the downhole tool assembly100, the time and cost associated with reducing formation damage can be reduced, thereby shortening the amount of time that the wellbore10is out of production.

Furthermore, because the formation fluid and/or reservoir fluid does not need to be passed to the surface30for treatment, the likelihood of spillage or leakage of fluid during transit to the surface30(FIG.1) may be reduced as compared to conventional configurations.

Accordingly, it should now be understood that embodiments of the present disclosure are directed to downhole tool assemblies that may be utilized to mitigate formation damage by “cleaning” wellbores. The downhole tool assemblies generally include a housing and a downhole motor. In some embodiments, a centrifugal pump is coupled to the downhole motor, and a filtration element is in communication with the centrifugal pump. The centrifugal pump and/or the filtration element may remove particulate matter from formation fluid drawn through the downhole tool assembly. By removing particulate matter from the formation fluid, the downhole tool assemblies may mitigate formation damage, as may result from drilling processes.

Having described the subject matter of the present disclosure in detail and by reference to specific embodiments, it is noted that the various details described in this disclosure should not be taken to imply that these details relate to elements that are essential components of the various embodiments described in this disclosure, even in cases where a particular element is illustrated in each of the drawings that accompany the present description. Rather, the appended claims should be taken as the sole representation of the breadth of the present disclosure and the corresponding scope of the various embodiments described in this disclosure. Further, it should be apparent to those skilled in the art that various modifications and variations can be made to the described embodiments without departing from the spirit and scope of the claimed subject matter. Thus it is intended that the specification cover the modifications and variations of the various described embodiments provided such modifications and variations come within the scope of the appended claims and their equivalents.

It is noted that recitations herein of a component of the present disclosure being “structurally configured” in a particular way, to embody a particular property, or to function in a particular manner, are structural recitations, as opposed to recitations of intended use. More specifically, the references herein to the manner in which a component is “structurally configured” denotes an existing physical condition of the component and, as such, is to be taken as a definite recitation of the structural characteristics of the component.