Channel Fracturing in the Remote Taylakovskoe Oil Field: Reliable Stimulation Treatments for Significant Production Increase

Abstract

The channel fracturing technique changes the concept of proppant fracture conductivity generation by enabling hydrocarbons to flow through open channels instead of through the proppant pack. The new technique is based on four main components: proppant pulsing at surface with fracturing equipment and software, a customized perforation strategy, a fibrous material to deliver stable channels, and a set of models to optimize channel geometry. The Taylakovskoe oil field is located in western Siberia—430 km away from the nearest settlements. The Jurassic reservoir in Taylakovskoe field is a sandstone formation with significant net pay (average 25 m) and middle-range permeability (3 to 20 mD). Bottomhole temperatures range between 85°C and 90°C. Fracturing gradient is typically 14 kPa/m. The majority of the wells are stimulated immediately after drilling. Sufficient fracture conductivity and effective fracture length are essential for adequate well performance. The optimization of hydraulic fracturing treatments conducted in recent years was based on improved fluid chemistry and pumping "aggressive" fracture designs; this yielded high-quality results. The new channel fracturing stimulation technique, which allows significant increases in fracture conductivity, became the next technological progression. With channels inside the fracture, fluid and polymer residue flow back faster than with a conventional proppant pack, improving cleanup and increasing effective fracture half-length. One of the most important advantages of the new technology is a very low risk of screenout events. The fibers make fluid more stable, while the presence of clean pulses around proppant structures promotes bridging-free flow. Reduced risk of premature treatment termination is even more important in remote operations such as in the Taylakovskoe field because of the higher costs of nonproductive time and deferred oil production. Candidate selection criteria were developed specifically for local conditions. Ten channel fracturing treatments performed in Taylakovskoe wells have already showed significant increases in incremental oil production—average 44% beyond expected production as shown by well performance analyses. We describe the performance evaluation of wells completed with this technology and future plans for applying channel fracturing methods in the Taylakovskoe field.

Modeling of Fracture Width and Conductivity in Channel Fracturing With Nonlinear Proppant-Pillar Deformation

“…Currently, when design calculations are performed, the ratio (s) of the formation's Young's modulus to closure stress (usually the minimum horizontal stress) is used to evaluate the applicability of channel fracturing in a particular formation, Schlumberger (2012) recommends that channel-fracturing technology is applicable when s > 275. The values of s for formations in various oil fields have been reported in the literature, such as 280 in Eagle Ford Shale (Rhein et al 2011), 287 in Zagorskoe Field (Kayumov et al 2014), 293 in the Barnett Shale Formation (Samuelson et al 2012), 312 in Taylakovskoe Field (Sadykov et al 2012), 419 and 556 in western Egypt (Gawad et al 2013;Emam et al 2014), 532 in the Ordos Basin (Li et al 2015a), 583 in Jonah Field (Turner et al 2011), 797 in the Burgos Basin (Valenzuela et al 2012), and 632 in the Shengli Oil Field. All these fields have a s-value greater than 275, and channel-fracturing stimulations generally lead to more than a 30% increase in production.…”

Experimental and numerical investigations of proppant pack effect on fracture conductivity of channel fracturing

“…This technology provides high fracture conductivity (ie, 2‐3 orders larger than conventionally propped fractures) and low cost due to reduced material usage, thereby decreasing the flow resistance of hydrocarbons and increasing production 14 . According to statistics, by applying channel fracturing technology, the improvement of hydrocarbon production ranges from 19% to 98% 15‐19 …”

“…14 According to statistics, by applying channel fracturing technology, the improvement of hydrocarbon production ranges from 19% to 98%. [15][16][17][18][19] Multiple studies have been published on the conductivity of channel fractures; for example, Medvedev et al 20 concluded that the discontinuous distribution of proppant packs largely enhances the channel fracture conductivity and determines the optimal channel width. Additionally, Zheng et al 21 found that with the increase in the distribution density of proppant packs, the channel fracture conductivity increased at the beginning and then decreased rapidly, while Xu et al 22 proposed that fracture width, propped area, and proppant embedment were the key factors affecting channel fracture conductivity.…”