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Mingazov, Arthur Failovich (Public Joint Stock Company, Slavneft-?egionneftegas) | Ibragimov, Kenes Rakhimovich (Public Joint Stock Company, Slavneft-?egionneftegas) | Samoilov, Ivan Sergeevich (Public Joint Stock Company, Slavneft-?egionneftegas)
Abstract The volume of drilling horizontal wells with multistage hydraulic fracturing (hydraulic fracturing) in Russia is increasing annually. According to statistics, at the company's licensed sites, drilling with multi-stage hydraulic fracturing currently accounts for over 70% of the volume of commissioning of new wells and sidetracking. The main reason for the growth of wells with multistage fracturing is a decrease in the quality of the reserves structure, the commissioning of low-permeable reservoirs, and a decrease in effective oil-saturated thicknesses in new areas. Currently, the share of horizontal wells with multi-stage hydraulic fracturing in an enterprise exceeds 25% of the existing fund. Wells with cementless multi-section shanks with ball-activated couplings for multistage hydraulic fracturing (ball arrangements) account for 97% of the well stock with multistage hydraulic fracturing. Hydraulic fracturing couplings and insulating annular packers (swellable, hydromechanical) are installed in the liner layout and are lowered into the horizontal wellbore. Further, during multi-stage fracturing, the couplings are activated alternately by dropping balls of different diameters (with an increase from small to large). The ball arrangements described above are disposable and have an uneven cross section after multi-stage fracturing. This multistage fracturing method is widespread, since it has a high speed of work and has no restrictions on the depth of the well. However, unequal borehole cross-section restricts access to the horizontal wellbore, and there is a need for drilling operations (milling) of couplings immediately after hydraulic fracturing or during well operation. The result of monitoring the flow rate of oil wells with multi-stage fracturing showed a decrease in productivity in the range of 55-75% for the first 2 years. In most cases, repeated stimulation is necessary, as there is a loss of productivity due to contamination of the fractures with process fluids and a deterioration in the conductivity of the hydraulic fracture (rock removal, plugging of the pore space of the fracture). For directional wells with hydraulic fracturing (Economidеs M. et al., 2004), there is a well-known method of restoring productivity - repeated hydraulic fracturing (re-fracturing). In the case of hydraulic wells with multi-stage fracturing with single-use ball arrangements, one of the problems is the selection of the optimal cost-effective method of repeated stimulation (multi-stage fracturing), which is technically complicated by the design of the well. In this paper, we consider the experience of applying the technology of re-stimulation of horizontal wells with multi-stage hydraulic fracturing at the company's fields and the results achieved after repeated hydraulic fracturing (increase in oil production rate, economic efficiency of measures). A proprietary method has been developed, which is currently the most acceptable and cost-effective for re-stimulation of horizontal wells with single-use ball arrangements.
Wenjun, Wang (China University of Petroleum and Petrochina Daqing Oilfield Co. Ltd.) | Lin, Wang (Petrochina Daqing Oilfield Co. Ltd) | Xingfu, Zhang (Petrochina Daqing Oilfield Co. Ltd) | Sun, Qingyou (Petrochina Daqing Oilfield Co. Ltd) | Tang, Pengfei (Petrochina Daqing Oilfield Co. Ltd) | Haitao, Wang (Petrochina Daqing Oilfield Co. Ltd) | Zhongsheng, Wu (Petrochina Daqing Oilfield Co. Ltd) | Qingtiao, Zhang (Petrochina Daqing Oilfield Co. Ltd)
Abstract For shallow burying, the temperature is less than 30°C and low pressure in Putaohua formations in Chaoyanggou area in Daqing oilfield. Eight horizontal wells have been drilled in the area and need hydraulic fracturing to improve the oil production. Two challenges have to be faced. One is how to rapidly completely breaking for gel at the low temperature and improve the flow-back ratio of fracturing fluid after the fracturing, to reduce the formation damage. It is difficult to gel breaking quickly with conventional breaker in the conventional hydraulic fluid system under the super low temperature. Another one is how to improve the production of fracturing in the horizontal wells. According to the characteristic of the horizontal wells in the low temperature, low pressure reservoir, some new technologies have been used in the 8 wells fracturing jobs, such as a new type low temperature breaker, a new type of cleanup, mechanical isolation staged fracturing. In this paper, we provide details about these new hydraulic fracturing techniques applied in the horizontal wells. The Application in eight wells just as the following aspects: According to the study in the lab, a new type of fracturing fluid system has been used to suit the low temperature. At 30°C, after 4h later, the fracturing fluid was broken, and the viscosity of fracturing fluid is 3.5mPa.s. Mechanical isolation and staged fracturing with two packers is used in the horizontal wells with high efficient treatment about 4 to 6 stages per day to improve the oil production. Base on above all, we get the good result of oil production on the 8 horizontal wells, about 5.2 times higher than that on vertical fracturing wells at the same area. In this paper, we provide details about these new hydraulic fracturing techniques applied in the horizontal wells. These new technologies of fracturing provide an effective method for the horizontal wells in low temperature reservoirs in Daqing oil field.
Al Ameri, Fahed (ADNOC) | Inukai, Hisashi (INPEX) | Al Zarouni, Asim (ADNOC) | Al Kindi, Mohammed (ADNOC) | Kawamura, Kazuhiro (JODCO) | Al Awadi, Farhaad Khaled (ADNOC) | Al Husseiny Afifi, Hassan (ADMA-OPCO) | Salman, Mohamed Wajeeh (ADMA-OPCO) | Moussa, Khaled Abdel-Ghani (ADMA-OPCO)
Abstract The first application of hydraulic fracturing in the offshore Abu Dhabi was executed safely and successfully. This achievement will be a valuable foothold to expand the field development target toward more challenging reservoirs such as deep tight sand in this region. There were huge amount of operational difficulties to carry out this hydraulic fracturing due to various operational restrictions, limited data availability and high-pressure & high-temperature (HP/HT) condition. Finally, these difficulties were successfully overcome by an intensive designing study on well completion, surface equipment, and operation associated with hydraulic fracturing for a tight gas reservoir. In this paper (Part 2), the key factors that led this trial to the first successful hydraulic fracturing in the offshore Abu Dhabi are described against the difficulties from operational point of view such as well completion design, arrangement of fracturing and surface testing equipment and acquired lessons learnt. However hydraulic fracturing design optimization from subsurface point of view is discussed in the other paper described by Kuroda, et al. (2014) as Part 1. Well completion design and equipment arrangement were optimized to overcome an extremely wide range of pressure and temperature condition with multi stage fracturing. Fracturing and testing equipment of high specification were arranged on the limited space of both the off-shore jack up rig and the fracturing vessel, and then these well-prepared equipment contributed to safe and accurate operation. Acquired lessons learnt will contribute to other offshore tight-sand gas reservoirs development in the offshore Abu Dhabi. These outcomes will be especially applicable in this region to optimize offshore hydraulic fracturing for tight HP/HT reservoirs in order to enhance the well productivity and enable economical development of marginal fields.
Loznyuk, O.. (Rosneft) | Surtaev, V.. (Rosneft) | Sakhan, A.. (Rosneft) | Murtazin, R.. (Rosneft) | Latkin, K.. (Rosneft) | Sitdikov, S.. (Rosneft) | Pestrikov, A.. (Rosneft) | Gusakov, V.. (Rosneft) | Politov, M.. (Rosneft) | Yudin, A.. (Schlumberger) | Vernigora, D.. (Schlumberger) | Olennikova, O.. (Schlumberger) | Bulova, M.. (Schlumberger)
Abstract One of the strategic targets in Yamal autonomous district, the Turonian siltstone formation, lies above the Cenomanian formation and is separated by a massive argillite barrier. Successful stimulation experience in vertical wells in the North-Kharampurskoe field during 2008 to 2010 encouraged the operator planning the next step of field exploration to consider horizontal well completions using multistage stimulation. The paper will describe pilot campaign in details. The Yamal Turonian formation was formed in a coastal marine environment with slow deposition rates and is composed primarily of siltstone. The major challenges of the Turonian formation are low permeability (∼0.5 md) and extremely high clay content—chlorite, kaolinite, illite, and mixed-layer illite-montmorillonite. The low temperature of the Turonian formation (below 80°F) also presents a significant challenge for gas production. An operator must produce at minimum drawdown to avoid hydrates creation. The shallow reservoir depth (∼ 3,000 ft) restricts recovering potential energy stored inside of the formation (initial reservoir pressure of about 1600 psi); therefore, hydraulic fracturing is a must for economic development of the Turonian formation. Selecting the correct fracturing fluid required extensive laboratory tests for compatibility and rheology adjustments. Thorough optimization of the fracturing fluid with clay stabilizer was applied during the course of this project. Additional challenges included proppant flowback tendency and inefficiency of conventional methods (resin-coated proppant) at such low temperatures. The project began by stimulating a vertical well that was used as a reference for the fracture horizontal well that was stimulated in three stages. Coring and a full logging suite were performed on the reference well, including acoustic measurements, post-frac, to obtain fracture height growth. It was shown that fracture is vertical at such depth and that it covers the whole interval without vertical growth into argillaceous barriers. Bottom hole gauges were used to complete the precise mechanical modeling of the stimulated reference well. Evaluation of the mechanical and properties were completed using E&P software platform-based simulator to optimize the multistage fracturing design in the horizontal well. This paper includes a detailed sequence of the operations performed and explains conclusions made concerning fracture geometry. The lessons learned during the assessment campaign are described. This stimulation project performed in the North-Kharampurskoe field is fundamental in development of the field and serves as important step toward unlocking the gas potential of other Turonian siltstones.
Abstract Hydraulic fracturing conductivity relies greatly on settled proppant size distribution and coverage area of the fracture. In low viscosity fluid systems, such as water or slickwater, dune structures are frequently deposited inside the fracture with proppant injected first landing near the wellbore, while proppant injected later transporting further out into the fracture length. Several experimental and modeling studies have been conducted to evaluate this dune-forming behavior, and numerous field treatments are designed to use it to advantage. This paper discusses the internal details of these dunes in light of the crossbeds that are created and the self-sorting of proppant particle sizes. Both behaviors can create streaks or layers of permeability within a dune structure and are similar in creation to geologic sedimentary structures created by Eolian and fluvial depositional systems. Such internal dune structures can degrade permeability within a fracture by forcing fluids to flow through baffles and potentially create barriers to flow. However, the self-segragation of proppant particle sizes may also lead to higher conductivities existing in a fracture than the bulk proppant sieve size may suggest. In either case, well productivity can be impacted and detailed modeling should consider accounting for these interdune structures.