This invention relates to a method for the control of solids acx-ampanying hydrocarbon production from subterranean formations. More particularly, the invention relates to a method for controlling the production of solids frαn weakly cemented or unσonsolidated formations during flew of hydrocarbon fluids from said formations.

When producing hydrocarbon fluids such as oil and/or gas from a formation, solids are frequently produced along with the fluids. These solids can range in particle size frαn very fine silt to very coarse grained material, depe__ding on the nature of the formation. Formations that produce solids vary frαn totally unconsolidated (imσemeπted) to weakly cemented. Fαrmatiαns having significant cαmpressive strength of about 500 psi (3500 KPa) or greater, do not produce solids under normal operating conditions. Various techniques are employed for controlling the production of these solids. One such technique is called gravel packing. Gravel packing involves filling an annulus or annular space between a casing and a retaining screen with a sieved particulate suci as sand, the casing having been previously perforated. For best results for well pπ_d__ctivity, sand also is placed into and through the perforation tunnels using pumping techniques. Subsequently, as the well is produced, sand serves as a filter media to restrain the movement and production of formation solids. The screen, in turn, prevents the movement of the sieved sand or "gravel".

In the practice of gravel packing, the major restriction to flow occurs in "gravel" filled perforation tunnels. Ηiis restriction is m_Ln__mized by utilizing as large a perforation density as is practical and Far exaπple, in conventional completions where gravel packing is not used, perforation densities rarely exceed four shots per foot (SPF) and are frequently less. In gravel packing operations, perforation densities are csaπmonly 8-16 SPF.

When performing gravel packing operations, sand or "gravel" is mixed with an appropriate fluid into a slurry and pumped down the wellbore in a manner designed to fill the perforation tunnels and any voids that might exist cxrtside the casing. Also, of course, the annular space between casing and reteining screen is filled. While successful in the majority of applications, gravel packs frequently fail to c___t_x>l solids production. A prime cause of failures occurs when the spaces designed to be filled with "gravel" are incαtpletely packed far one reason or another. As a result, voids are left in the pack. During subsequent production, formation solids are produced t____O_κ£ι them. Far these reasons, placement of gravel becomes a major operational consideration in achieving successful gravel packs.

Therefore, what is needed is a method for effectively gravel packing a wellbαre which packing will fill all desired spaces.

The invention provides a method far .unproved gravel placement in perforations and a created fracture, as well as voids adjacent to a well.

Moreover the invention enables a wellbαre tube gravel packed without the need for a retaining screen.

In accordance with one aspect of the present invention

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there is provided a method for controlling solids contained in hydrocarbonaceous fluids produced frαn a subterranean formation comprising:

a) perforating a wellbαre at a productive interval of 5 a hyirtx-arhonaσeαus fluid-cxar±aining formation;

b) injecting into said productive interval via perforations a fracturing fluid c___t_aining a resin- coated particulate material which is of a size and σαrpbsition sufficient to prep a created fracture

10 and form a permeable consolidated mass therein;

c) fracturing hydraulically said productive interval and thereafter c__eating a propped fracture with a consolidated permeable mass therein as well as within said perforations and wellbαre which mass

15 has filtration properties and composition sufficient to restrain solids entrained in said hydrocarbonaceous fluid; and

d) removing mechanically the consolidated permeable mass frαn said wellbore which allows hydrocai±on-

20 acecus fluids to be produced from the fαriration substantially solids free which solids are restrained by the permeable consolidated mass within the fracture and perforations.

A In accordance with another aspect of the invention there

25 is provided a method for cxmtrolling solids c__ntctined in hydrocarbonaceous fluids produced f αn a siibterranean formation

ccπprising:

a) perforating a wellbαre at a productive interval of a hydrocarbonaceous fluid-ccntaining formation;

b) injecting into the wellbαre a fluid cxxitaining a resin-coated particulate material which fluid fills the wellbore to a level above perforations contained in the wellbore whereupon pressure less than the formation fracturing pressure is applied thereby causing the particulate material to be forced into said perforations where it forms a permeable consolidated mass having filtraticn properties and composition sufficient to exclude entrained solids frαn the produced hyd_xx_arbonaceσus fluid;

c) allowing said material to farm said consolidated . mass within the perforations and wellbore; and

d) ___τoving mechanically the consolidated permeable mass from the wellbαre which leaves the perforations packed with the consolidated mass so as to remove eaitrained solids frαn hydιrocart__naσeous fluids produced frαn the formation.

Reference is now made to the aσccqpaπying drawings, in which :

Figure 1 is a schematic representation of a formation penetrated by a wellbαre which depicts a hydraulic fracture and

wellbore filled with a permeable, porous consolidated mass; and

Figure 2 is a schematic representation which shows a fracture and perforations filled with the permeable, pαrcus consolidated mass which mass has been removed frαn the wellbαre.

In the practice of this invention, referring to Figure 1, wellbore 12 penetrates formation 10. Wellbore 12 contains a cement sheath 14 and casing 16. Perforation tunnels 18 penetrate cement sheath 14 and casing 16. Thereafter, a fracturing fluid is injected into well 12. This fracturing fluid contains a resin-coated particulate material. This resin-coated particulate material is placed in the flecturing fluid in an amount sufficient to prop created fracture 20 and also to fill perforation tunnels IB. Ωie coated particulate material is also of a size and strength sufficient to prop fracture 20.

Additionally, it is also of a size and composition to farm a permeable, porous consolidated mass in created fracture 20.

Ihe fracturing or "frac" fluid is injected into well 12 and into the productive interval of fconation 10 at rates and pressures sufficient to create a hydraulic fracture. Upon entering the fracture, fluid leaves the resin-ooated material and drains into formation 10. Fracturing fluid is cxa -JLπually puπped into wellbαre 12 until such time as "sand out" or "screen cut" occurs in the fracture as well as perforation tunnels 18. As the liquid portion of the fracturing fluid leaks off into formation 10, the resin-coated particulated material forms a plug 22 within wellbore 12. The "screen out" results in a fill-up of well 12 to a predetermined level above the perforations. Once a fracture has been formed to the extent desired in fσπration 10, hydraulic fracturing is terminated.

The resin-coated particulate material which has been injected into fracture 20, wellbαre 12, and any voids adjacent thereto, forms a permeable, porous consolidated mass in fracture 20, said voids, and a permeable, porous consolidated plug in wellbore 12. The resin-coated particulate materials solidify into a consolidated, porous, permeable body with a desired cσmpressive strength. Consolidation time depends on the fluid, oil or water base, used for pumping as well as bottom hole t_aιperature and pressure conditions. When the consolidation process achieves a desired and predetermined compressive strength, the resin-coated particulate material in the wellbore is drilled out and excess material is circulated to the surface. The size of the hole drilled "through the consolidated mass or resin consolidated "gravel" plug can be regulated by the size of the drill bit utilized that is affixed to a drill string.

C___trali_ati3n of the drill string with stabilizer assemblies may also be desirable. After completion of the drilling and cleaning out process when the permeable, porous consolidated mass has been removed from wellbore 12, a thin layer 24 of resin-coated gravel may remain in wellbαre 12. This is depicted in Figure 2. After the porous consolidated mass has been removed frαn wellbαre 12, the perforatiαns and fracture remain packed with the consolidated porous mass.

Prior to hydraulically fracturing the formation, perforation tunnels 18 are placed in wellbore 12. These perforation tunnels are made by utilization of perforation guns which methods are known to those skilled in the art. The density of perforation tunnels IS in wellbore 12 will generally be spaced about 4 to about 16 shots per foot. In a preferred embodiment of this procedure, perforation tunnels can be made fcy in-line shots using zero degree or 180 degree

phasing. Additional improvements can result by aligning the perforation tunnels in a preferred direction so that the desired fracture orientation is obtained. Other perforating directions can be selected as will be apparent to those skilled in the art. thαugh Figures 1 and 2 depict hydraulic fracturing in a vertical wellbαre, the method of this invention can also be used in horizontal and deviated wellbαres. A hydraulic fracturing technique which can be utilized herein is disclosed in US-A-3,929,191. This patent also contains a more detailed description of standard industry practices wherein heat curable particles are used in hydraulic fracturing and gravel pack coπpletion operations.

In another embodiment, a fracturing fluid as mentioned above is pumped into the bσttαn of wellbαre 12 where it fills it to a predetermined level above perfαratiαn tunnels 18. When the perforation tunnels are covered, pump pressure will increase. The fracturing fluid containing the resin-coated particulate material is foroed through perfαratiαn tunnels 18 by maintaining a higher pressure within wellbαre 12. A process of this type is referred to in gravel packing technology as pressure packing or pre-packing perforatiαns. Once the injecting or puπping pressure has increased, injection of the fracturing fluid into perforation tunnels 18 is ceased. The pressure utilized in this embodiment remains belcw the fracturing pressure of the formation. Liquid αaπtained in the fracturing fluid flows into formation 10 while the resin-coated particulate matter fills perforation tunnels 18 and wellbore 12. As was mentioned previously, the resin-coated particulate material is allcwed to remain in perforaticai tunnels 18 and wellbαre 12 until the consolidation process is completed.

Once the consolidation process is completed, a permeable, porous consolidated mass is formed within perforation tunnels 18, wellbαre 12, and within any voids adjacent thereto. The filtration cihciracteristics of the consolidated material is such as to prevent the flow of entrained solids in the hyd_x_a____onaσeαus fluids from wellbαre 12. Once the resin-coated particulate material has consolidated to the extent desired in perfαratiαn tunnels 18 and wellbαre 12, excess consolidated material is drilled out and circulated frαn wellbore 12. Consolidated porous material remains in perforation tunnels 18 and in void areas outside of cement sheath 14 adjacent to formation 10. In the latter embodiment, the density of the perforation tunnels made in the we lbore will be spaced so as to be about 4 to about 16 shots per foot with no preferred phasing. Additionally, perforation wa_=hing or staging techniques, familiar to those skilled in the art, may be employed prior to pressure packing with the feacturing fluid. Utilization of either of the preferred embodiments provides a means for improved "gravel" placement within perforations and when fracturing, and provides improved "gravel" placement within a fracture. This increases the probability that all perforations will be treated with the fracturing fluid cx_r_ta__ning the res__n-coated consolidated material. The resin-coated consolidated material or "gravel" will have sufficient strength to remain in place so as to constrain the irovemeπt of formation solids. In this manner, the need for a retaining screen is eliminated.

The resin-coated particulate material can comprise sand or "gravel". This resin-coated consolidated material may be either sand or a synthetic particulate known in hydraulic fracturing t__α nology as an intermediate strength prcppaπt, or "ISP". Two products that can be used for this purpose are Super

Sand v_hich is manufactured by Santrol Products, Inc. of Houston, Texas, and Acfrac C , manufactured by Acme Resin Cαpany of Westchester, Illinois. Super Sand and Acfrac materials are discussed in US-A-4,888,240. Another coated particulate material which can be utilized is disclosed fcy Armbruster in US-A-4,694,905.

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