Proppants production

The flowback of a proppant following fracture stimulation treatment is a major concern because of the damage to equipment and loss in well production. The mechanisms of flowback and the methods to control flowback have been recently discussed in the literature [ 1343]. To reduce proppant flow-back, a curable resin-coated proppant can be applied [1349]. The agent must be placed across the producing interval to prevent or reduce the proppant flowback. 

The fracture must be wide enough to permit entry of proppant to a distance sufficient to stimulate production. Tons of proppant are normally required to fill this void. Therefore the fracturing fluid must suspend the proppant long enough for it to be transported and placed, by flow, throughout the fracture. To preserve the maximum accessible flow area, the proppant should be uniformly suspended inside the entire propped fracture area while the fracture closes. Kaspereit(15), as well as Smith(16), has made the point that fracture conductivity can be a limiting factor. If the... 

Hydraulic fracturing is a method of stimulating production of oil or gas from rock formations. A fluid is pumped under conditions of high pressure and high rate Into the formation to fracture it. The fluid also carries sand or a similar proppant material into the fractures. When the pumping is stopped and the hydraulic pressure is released at the wellhead, the fracture partially closes on the sand leaving a highly permeable channel for the oil or gas to flow back to the well. 

Hydraulic fracturing in conjunction with gravel packing (87-90) creates a short wide fracture that is packed with gravel (proppant) sized to prevent solids production. A high flow rate into the well can be maintained without solids production because fluid flows across the fracture face at rates below the critical solid production rate. 

Horizontal well drilling has increased throughout the industry in recent years and is being evaluated as an economical means to improve hydrocarbon production from some reservoirs (44-47). Perforation and fracture are the two major concerns for proppant transport when a eonven-... 

Polymer requirements are dictated by the specific application. In drilling, the polymers must be shear stable and provide a means of suspending and removing formation cuttings. For use in hydraulic fracturing, the polymeric fluid must also suspend solid proppants, help control fluid loss, reduce friction and provide viscosity for the creation of fracture width. However, after the treatment the polymer containing fluid must be degradable, so that it can be readily returned from the formation and not interfere with oil and gas production. 

The materials commonly used as proppants can be grouped into three main categories, listed in Table 10.25. The first proppant material used was rounded silica sand mined from glacial deposits. This material was initially selected owing to both its wide availability near production wells and its low cost, but since the early days several other industrial materials have been selected and used as proppants, and today we observe the increased use of synthetic materials, especially sintered and fused ceramics. The main impetus in focusing on ceramics was driven by the fact that ceramic materials offer suitable properties for use in modern deep wells today. 

Many shale gas service companies use groundwater pumped directly from the formation or treated water for their fracturing jobs. In some well stimulations, proppants are not needed to prop fractures open, so simple water or slightly thickened water can be a cost-effective substitute for an expensive polymer of foam-based fracturing fluid with proppant (Ely, 1994). Hydraulic fracturing performance is not exceptional with plain water, but, in some cases, the production rates achieved are adequate. Plain water has a lower viscosity than gelled water, which reduces proppant transport capacity. 

Proppants, usually composed of sand and occasionally glass beads, prop or hold fissures open, allowing gas to flow out of the cracked formation. An ideal proppant should produce maximum permeability in a fracture. Fracture permeabUity is a function of proppant grain roundness, proppant purity, and crush strength. Larger proppant volumes allow for wider fractures, which facilitate more rapid flowback to the production well. Over a period of 30 minutes, 4500 to 15,000 gal of fracturing fluid will typically transport and place approximately 11,000 to 25,000 lb of proppant into the fracture (Powell et al., 1999). 

Proppants. Millimetre-sized ceramic particles, forced with hydraulic fluids into fractures in oil and gas wells, to keep them open. The productivity of the wells is thus enhanced. 

In addition to scale particles, produced water often contains other suspended solids. These include formation sand and clays, stimulation (fracturing) proppant, or miscellaneous corrosion products. The amount of suspended solids is generally small unless the well is producing from an unconsolidated formation, in which case large volumes of sand can be produced. Produced sand is often oil wet and its disposal is a problem. Sand removal is discussed in a later subsection entitled "Equipment Description" under Section 3.6. 

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