The Volga-Urals basin is one of the largest oil-producing regions in Russia. Orenburg region, located in Volga-Urals, has more than 100 oil fields with great variety of formation properties. The majority of formation fluids are characterized by high gas/oil ratio (GOR) and high bubblepoint pressure. Today, most reservoirs are depleted and produce at bottomhole flowing pressure below bubblepoint pressure. These factors yield multiphase and non-Darcy flow in propped hydraulic fractures, which drastically decreases production. As a result, hydraulic fracturing treatments with conventional proppant are not effective.
Proppant flowback is another critical problem after hydraulic fracturing. There are a few solutions widely accepted by industry, and one of the most popular is a resin-coated proppant (RCP). Usually the coating is activated by temperature; however, for formations with low bottomhole static temperature (BHST), RCP may not be efficient. Many formations in Volga-Urals have a low BHST, which requires a different technology from RCP to eliminate proppant flowback.
A recently developed rod-shaped proppant was proposed as a solution to both problems specified above. In comparison with conventional proppant, it provides higher fracture conductivity with integrated flowback control due to random alignment of proppant grains while packing. This property results in improved fracture cleanup from treating fluids. The rod-shaped proppant also acts to prevent proppant flowback through specific shapes of grains. The significant benefit over conventional RCP is that rod-shaped proppant does not have any BHST limitations, does not require any chemical activation, and does not have special flowback requirements.
Since the introduction of rod-shaped proppant in Russia, 10 fracturing treatments have been successfully carried out with this new proppant in Vakhitovskoe, Lebyzhinskoe, Vostochno-Kapitonovskoe, and Sorochinsko-Nikolskoe oil fields. Well production analysis proved that rod-shaped proppant was more effective than conventional proppant: productivity index is 26 to 67% higher. Further, no proppant flowback issues were detected on wells fractured with rod-shaped proppant. The first successful implementation of this product in Russia is described in detail with laboratory data, a thorough production analysis, and case histories.