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Abstract This paper discusses laboratory studies to determine the nature of channel growth and stability in proppant packs with and without fibers. Tests were performed with proppant packs in three different types of experiments using natural sand and ceramic proppants, gas and water flow, and either perforations or an open proppant pack face. Proppant packs without fibers fail at low fluid velocities by the formation of voids at perforations or across the entire front of the proppant pack. Only when imperfect proppant packing was suspected did a channel form without fibers. Proppant packs with fibers form channels that are 2-10 cm wide depending on fluid velocity. The channel length increases in stepwise progression with increasing flow rate (velocity). The proppant pack on the either side of the channel supports the closure stress. Channels are stable over time at constant flow rate. Channels grew with fibers in all conditions tested. Random fibers mixed with the proppant extend the fluid velocity range for channel growth to much higher values. P. 665
Abstract Egypt's Western Desert reservoirs are characterized to be tight clastic reservoir. In the early development stages only layers with high permeability were produced while tight formation was not considered economic due to application of conventional completion strategy resulting in very low production results. With the decline of Egypt's hydrocarbon production and increase in domestic demand of energy, economically production from these tight reservoirs is a great challenge to maintain production's annual decline. The prospective of these tight producing zones were discovered at a depth below 14,000 feet where the stress is extremely high (1.1 psi/ft) and the reservoir permeability conditions are low with range of 0.2 mD; being necessary in all cases to fracture stimulate each horizon to define the fluid and evaluate productivity. The extreme stress condition and high fracturing treating pressure, risk of premature screen out are one of the main challenges to perform fracture stimulations on these formations which exceeded the working capability of the available equipment in addition; it required significant amount of horsepower on location. Initially, the conventional fracturing treatment was conservatively designed in terms of treatment rate, polymer loading of fracturing fluid and proppant concentration to manage both risk and treatment proppant placement. However, this conservative approach impaired proppant-pack conductivity and the effectiveness of the fracture half-length However, premature screen-outs severely disrupted stimulation operations, leading to costly nonproductive time and deferred production. The poor results using these conventional fracturing techniques during initial exploration and development, the wells were deemed uneconomical. The recent advances in channel fracturing technology; enabled operators to unlock the potential of their toughest reservoirs to economically produce and unlock the enormous amount of hydrocarbons retained in the rock, prolong life of mature fields and achieve production targets. With the application of this technique, helps alleviate the risks of screenout and mitigates the proppant bridging buildup, as the proppant is added in pulses along with dissolvable fibers. These proppant pillars are suspended and held in place by fibers during the treatment. Once pumping is stopped, the fracture closes on the proppant pillars and the fibers degrades under effect of formation temperature. These pillars hold stable channels along the entire geometry of the fracture that provide open pathway for hydrocarbons to flow in near-infinite conductivity. Additionally, 40% less proppant was used and reducing pump rates, which lowered horsepower requirements by 30%. Results indicate that the channel fracturing technique has significantly impacted wells' performance and achieved the desired objectives over conventional fracturing methodologies. Positive features that were observed such as reduced net pressure increase estimates, elimination of near-wellbore screen-outs.
The new channel-fracturing technique is capable of increasing fracture conductivity by up to two orders of magnitude. The channel-fracturing technique allows development of an open network of flow channels within the proppant pack, enabling fracture conductivity by such channels rather than by flow through the pores between proppant grains in the proppant pack. The successful implementation of the channel-fracturing technique in brownfield development is described in detail with the case study of the Talinskoe field in Russia. The Talinskoe section (for simplicity, referred to herein as the Talinskoe field) is part of the medium-sized, mature Krasnoleninskoe field, located near Nyagan, Russia. Exploration of this section began in 1982.
Gawad, A. A. (Apache/Qarun Petroleum Company) | Long, J.. (Apache/Qarun Petroleum Company) | El-Khalek, T.. (Apache/Qarun Petroleum Company) | Bashandy, R.. (Apache/Qarun Petroleum Company) | Mabrouk, T.. (Apache/Qarun Petroleum Company) | Shaaban, A.. (Schlumberger) | Mathur, A.. (Schlumberger) | Yosry, M.. (Schlumberger) | Kraemer, C. C. (Schlumberger) | Bernechea, J. M. (Schlumberger)
Abstract This paper describes the application for the first time of a novel channel fracturing technique combined with rod-shaped proppant in selected production targets in several fields in the Egyptian western desert. The channel fracturing technique introduces channels within the proppant pack that increase conductivity and effective half-length leading to increased productivity (Gillard et al. 2010). Rod-shaped proppant when used as tail-in in fracturing treatments increases near-wellbore fracture conductivity and prevents proppant flowback due to its particular geometry (McDaniel et al. 2010). The western desert fields in the Qarun concession area in Egypt are characterized as complex, thin-bedded sequences with heterogeneous laminated sandstones producing mainly from the Abu Roash and Upper Bahariya formations. Hydraulic fracturing has traditionally been employed to produce hydrocarbons from these marginal reservoirs. The channel-fracturing technique was first introduced in the Amana fields in late 2012 combined with rod-shaped proppant for flowback control and conductivity enhancement. Early-time normalized production of the wells fractured with this technique increased by 89% over offset wells fractured conventionally, and the application of the channel fracturing technique eliminated the incidence of premature screen-outs in all fields. The positive results from implementation of this combined stimulation technique have led to a vigorous expansion of its utilization throughout Egypt's western desert area, including a refracturing campaign for older wells where conventional fracturing techniques did not yield the desired results.
Yudin, Alexey (Schlumberger) | Rakhmatullin, Marsel (Schlumberger) | Sadykova, Dinara (Schlumberger) | Olennikova, Olesya (Schlumberger) | Fedorov, Andrey (Schlumberger) | Miklin, Yuri (Rosneft) | Bernyaev, Mikhail (Rosneft) | Kovalevskiy, Alexey (Rosneft)
Abstract Western Siberia has a long and successful history of channel hydraulic fracturing technology implementation. However, there is an urgent need to further reduce the cost of hydraulic fracturing. As a solution, it was proposed to use local suppliers of quartz sand to replace a substantial proportion of the more expensive ceramic proppant. Based on the principles of the classical channel fracturing, fracture permeability is provided by creating open channels in the intervals between proppant clusters. Open channels are created by feeding proppant in pulses simultaneously with a continuous supply of fiber, which subsequently dissolves under the action of reservoir temperature. The use of quartz sand during hydraulic fracturing in reservoirs with high stresses is thus possible only with the channel fracture method of proppant placement and is justified by the fact that the fracture conductivity in this case does not depend on the permeability of the proppant itself. Open channels play a key role. Thus, the need to reduce the cost of service is justified not only economically, but also technologically. The first step in the implementation of the technology was the successful application of traditional channel fracturing using ceramic and resin-coated proppant at the fields in the Uvat region, more than 60 operations in total. The best results on productivity were obtained in multi-stage hydraulic fracturing operations in horizontal wells, where additional effects of up to 20% relative to the standard method were obtained. Advantages in the form of accelerated operations (up to 15%) were also confirmed by reducing the duration of the preparatory work; minimize workover cleanouts after premature screen-out due to minimized risks since fibers and pulses of pure liquid ensure better proppant admittance. Significantly reduced costs for logistics and storage of proppaant, which is most relevant in the conditions of autonomous fields. As a result of a successful pilot campaign, it was decided to test injection of quartz sand during channel fracturing operations. Laboratory tests have been carried out and a risk analysis has been formalized, which described in detail in following sections. The first candidates during the pilot campaign were injection wells followed by a testing plan at a producing well stock. The experience of using quartz sand during hydraulic fracturing is innovative for sandstones after numerous attempts at the hydraulic fracturing dawn decades ago that revealed insufficient sand conductivity and required a switch to expensive ceramic proppant. The reincarnation of the perspectives of quartz sand in medium permeability reservoirs was provided by the channel fracturing method, which removes the connection between proppant permeability and fracture conductivity due to the presence of open channels. The experience in the Uvat region will be the first published in Russia and will allow further developments in this direction.