Gravel Pack Equipment and Tools

8/11/2019 Gravel Pack Equipment and Tools

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Gravel pack equipment and tools

A myriad of gravel-pack systems are available to handle virtually any conceivable well condition.Gravel pack completion equipment is the equipment that remains in the well after the gravelplacement operations are complete. The equipment discussed next does not represent all the typesof available equipment, but it does represent a typical gravel pack completion. Certain well

conditions may require compromises in the type and design of gravel-pack equipment that can beused. Another important concept is that there may be several, yet equally effective, ways tocomplete a well.

Typical gravel pack

Fig. 1 illustrates typical gravel packs for cased and openhole completions. These employ crossover gravel packing equipment that is state-of-the-art in the industry today. Washdown and reversecirculation methods are other alternatives that are less expensive and are to be used when costswill not support crossover equipment.


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Fig. 1 Typical gravel-pack completion equipment in cased- and openholes (courtesy ofBaker Oil Tools).


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Gravel pack base

The first step in installing a gravel-pack completion is to establish a base on which the screen willrest. In cased-hole completions, the most common type base is a sump packer . The sump packer isnormally run into the well on an electric wireline before perforating and is set a specified distance(5 to 10 ft) below the lowest planned perforation. The distance below the perforations must

accommodate the length of the seal assembly and production screen overlap .

Although sump packers are the preferred gravel-pack base, other options such as a bridge plug orcement plug can be used. In openhole completions, provisions for a debris sump or logging accesscan be achieved, but these are not routine and may not be feasible in some situations. Therefore,the gravel-pack base is normally a bull plug on the bottom of the screen. The types of commongravel-pack bases are illustrated in Fig. 2 .

Fig. 2 Types of gravel-pack bases (courtesy of Baker Oil Tools).

Seal assemblyThe seal assembly is required to establish a seal in the bore of the sump packer to prevent gravel-pack sand from filling the bottom of the well during gravel packing. In the case of multiple gravelpacks, the seal also provides for zonal isolation. The seal assembly used to engage the sump packeris normally a snap latch type or other type hold down.


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Fig. 3 Gravel-pack crossover tool positions (courtesy of Baker Oil Tools).

The squeeze position is located by positioning to seal the return ports. The squeeze position allowsall fluids pumped down the work string to be forced into the formation. It is used to performsqueeze gravel-pack treatments and/or inject acid treatments into the formation. The circulatingposition is located by picking the crossover tool up approximately 18 in. above the squeezeposition. The circulating position works with a properly sized washpipe to provide a flow path tocirculate gravel-pack sand to completely fill the screen/casing annulus. The fluids flow down thework string into the crossover tool, out the gravel-pack extension, down the screen/casing annulusinto the screen, up the washpipe into the crossover tool again, and up the work string/casingannulus. Special, high-rate, erosion-resistant crossover tools are available for high-rate brine orfrac-pack completions.

Washpipe


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Washpipe is run below the gravel-pack crossover tool inside the blank pipe and screen to ensurethat the return circulation point for the gravel-pack carrier fluid is at the bottom of the screen. Thewashpipe assists in placing gravel-pack sand at the bottom of the screen and packing from thebottom up. The end of the washpipe should be as close to the bottom of the screen as possible.

Maximizing the washpipe outer diameter (OD) increases the resistance to flow, preferentially intothe washpipe/screen annulus. The greater resistance to flow forces the gravel-pack transport fluidto flow in the screen/casing annulus and carry the gravel-pack sand to the bottom of the well. Thatcauses the gravel packing of the screen/casing annulus to be more complete. The optimum ratio ofwashpipe OD to screen base pipe ID should be approximately 0.8. Achieving this ratio in somescreen sizes will require the use of special flush-joint washpipe connections.

Gravel Pack Equipment and Tools

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