Diffuser assembly

#The present invention relates in part to devices and methods used in oil and gas drilling operations to diffuse aggregations of lost circulation materials (LCM) which are used to resolve lost circulation and fluid losses, and more particularly to such devices which include elements for breaking down larger masses of LCM during the diffusion step.

#When drilling oil and gas wells, under proper conditions during the drilling process, drilling fluids and drill cuttings are circulated away from the drill bit into the annulus around the drill stem and brought to the surface. Such drilling fluids are also important for providing hydrostatic pressure to prevent formation fluids from entering into the well bore, keeping the drill bit cool and clean during drilling, and suspending the drill cuttings while drilling is paused and when the drilling assembly is brought in and out of the hole. Because proper circulation is critical to the drilling process, any lost circulation is a significant problem that must be overcome for drilling to recommence.

#Lost circulation is the partial or complete loss of drilling fluid or cement slurry to the formation during drilling or cementing operations or both. Lost circulation can be brought on by natural causes, such as naturally fractured formations or unconsolidated zones, or induced causes, such as when the hydrostatic fluid column pressure exceeds the fracture gradient of the formation and the formation pores break down enough to receive (rather than resist) the fluid. When lost circulation occurs, it typically results in the new expenditure of time and mud or cement, adding substantially to the overall cost of a well.

#For a further understanding of the nature, objects, and advantages of the present invention, reference should be had to the following detailed description, read in conjunction with the following drawings, wherein like reference numerals denote like elements.

#FIG. 1 shows a side sectional view of a carrier sub, such as a stabilizer or other type of downhole sub, containing a preferred embodiment of a diffuser screen of the present invention.

#FIG. 2 shows a side view of the diffuser screen of FIG. 1.

#Before the subject invention is further described, it is to be understood that the invention is not limited to the particular embodiments of the invention described below, as variations of the particular embodiments may be made and still fall within the scope of the appended claims. It is also to be understood that the terminology employed is for the purpose of describing particular embodiments, and is not intended to be limiting. Instead, the scope of the present invention will be established by the appended claims.

#In this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural reference unless the context clearly dictates otherwise. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this invention belongs. Unless otherwise specified herein, all materials of construction are preferably steel resistant to the corrosive effects common in oil and gas production environments. As used herein the term “conduit” shall mean any tubular member into which the diffuser 1 can be installed for the purpose of allowing LCM-containing fluid to flow through the conduit and be broken apart, or diffused, by the diffuser 1. Non-limiting examples of conduits may be a carrier sub, drill pipe, stabilizer, or other tubular member such as shown in the figures.

#Turning now to the figures, a preferred embodiment of the present invention is shown in FIGS. 1-6 as a diffuser assembly 1 comprising a diffuser 2 adapted to reside within a conduit in the form of a carrier sub 3, having an upper mounting member 4 mountable within the carrier sub 3 and having an fluid inlet port 5, and a lower section having a diffuser screen 6. As shown in more detail in FIGS. 4 and 6, a plurality of cutters 7 are removably attached to the diffuser screen 6, wherein the cutters 7 are radially oriented relative to a central axis 8 of the diffuser screen 6. The diffuser screen 6 is a cylinder having a plurality of diffuser slots 9 formed therein and a bottom cap 10 having a fluid port 11.