Changing the Shape of Fracturing: New Proppant Improves Fracture Conductivity

Abstract

Hydraulic fracturing is used extensively to increase hydrocarbon production from oil and gas formations. Hydraulic fracture conductivity is a key parameter in optimizing the productivity of a well after the fracture treatment. The American Petroleum Institute (API) proppant permeability / fracture conductivity testing results are frequently used in industry fracturing models when selecting the proppant that provides the optimum fracture conductivity for a well's particular reservoir properties. This design methodology invariably results in a lower than expected fracture conductivity and in many cases, lower than optimum well performance. The industry has recognized that actual fracture conductivity is often a small fraction of what would be expected by using API test results. Non-Darcy flow, multiphase flow, gel damage, stress cycling, fines migration, proppant embedment, proppant flowback, and fracture cleanup are some of the parameters that result in fracture conductivities significantly lower than those measured in an API conductivity test. A new proppant was developed to improve the final fracture conductivity achievable with high-strength spherical proppants currently available in the market place. This new product is an elongated rod-shaped, high-strength particle with integrated proppant flow back control. Initial field testing of the product was conducted in moderate permeability formations where production from prior fracture treatments indicated lower than optimum fracture conductivity. Production results from these field tests confirmed that substantial increases in fracture conductivity can be achieved. The large improvement seen in fracture conductivity can be attributed to increased porosity of the proppant pack and reduced fracture conductivity losses due to non-Darcy and multiphase flow effects. Completely changing the typical geometry of proppants used in hydraulic fracturing is a viable option for improving the conductivity of hydraulic fractures to a point not currently obtainable with spherical proppants.

Optimization of hydraulic fracturing with rod-shaped proppants for improved recovery in tight gas reservoirs

“…A unique consolidated proppant pack can be created due to the cylindrical shape which can resist the proppant flowback. Another added advantage is the mobility increase of a high-viscosity slurry, which can help in quick fracture cleanup due to higher available permeability (Cheremisin et al 2011;Jia et al 2019;Li et al 2015;McDaniel et al 2010;Osiptsov 2017;Schlumberger 2013Schlumberger , 2015Soetikno et al 2014). The field tests indicated that the friction pressure for rodshaped proppants was 492 psi/1000 ft, significantly lower than 543 psi/1000 ft for spherical particles for an equivalent volume of particles in the slurry.…”

“…During the settling phase until fracture closure, the fracture conductivity can be reduced if the proppants settle perpendicular to the flow direction. However, multiple slot flow and proppant settling tests revealed that the proppant alignment after settling was completely random (McDaniel et al 2010). Moreover, the proppant diameter should be chosen according to the fracture aperture to avoid any entry restrictions in the fracture.…”

“…Successful field trials have demonstrated that the existing wellsite equipment can perform the fracturing operation with this new proppant even at high volumes of 100,000 lbm per job. These proppants reduce friction pressure, which lowers the surface injection pressure, and significantly enhance the productivity index compared to conventionally fractured wells (McDaniel et al 2010). Longer effective fracture half-lengths due to better and quicker cleanup and higher conductivity of rod-shaped proppants increased the cumulative production by at least 12% after a six-month production period compared to hydraulic fracturing with conventional proppants (Carpenter 2016).…”

Refracturing field tests for enhanced coalbed methane production with gas wettability alteration

“…Compared with spherical proppant packs, the elongated proppant packs also demonstrated the advantage of reducing the friction pressure. When elongated shaped materials align in a fluid flow, they can help minimize the turbulent effects that can help to reduce losses due to friction 32 (see Figure 3).…”

“…For enhanced energy recovery, elongated proppant has already been implemented successfully in many field tests. McDaniel et al 32 reported the first field implementation, proving the possibility of using elongated particles as proppant. The channel fracturing technology with rod‐shaped proppant has been conducted and achieved good performance in a lot of field tests around the world 33‐35 .…”