Historically, coiled tubing (CT) services were positioned as highly tailored services in Russian Federation. Main operations for CT application were post-frac cleanouts (CO) and kick-off (KO) of vertical and slightly deviated wells. Lately, with increasing of horizontal wells quantity, CT application scope became wider: logging, perforating, fishing jobs, CO, milling and other operations. With increasing interest to multi-stage hydraulic fracturing technology, Coiled Tubing application has to grow to meet client demands. In wells with horizontal section 1000 m long, milling of different sizes balls and seats became the most challenging and efficient technical solution. Located in Khanty-Mansiysk District of Western Siberia, Priobskoe field is one of the world’s largest oilfields. Due to low permeability almost 80% of reserves are hardly recoverable. Oilfield development plan include post drill fracturing of all new completed wells. In order to maximize the hydrocarbon recovery field-proven technology enabling multi-stage hydraulic fracturing of an uncemented completion in one pumping treatment became a consistent decision for well treatment. For the first job following workflow was applied: multi-stage hydraulic fracturing completion was installed and 7 zones were fractured one by one. Technology implies that during pumping, at specified stage time, balls are dropped (one at time) from the surface to open the Frac Ports (FP). After the treatment, the most efficient technical solution to remove the balls is to mill them using CT. Following milling operations the well was cleaned out and kicked off with nitrogen. In designing a Coiled Tubing job the critical part is BHA and string selection. Selected mill should be strong enough for milling Frac Port iron and long enough to prevent damage of FP, by side tracking from it to reservoir. As per project program 4 wells have been completed with technology described above. Current production rates show high efficiency of multi-stage hydraulic fracturing technology over traditional well completions. This article describes technical and operational details of the project, candidate selection process, job planning and determines a way to find an optimum technique to meet client demands. Analysis of 4 wells completed with multi-stage fracturing liner is shown in comparison with standard completion in the article.
The Caspian Sea region, which includes Russia, Azerbaijan, Kazakhstan, Turkmenistan, Uzbekistan, and Iran, is one of the oldest oil-producing areas in the world and is an increasingly important source of global energy production. The area has significant oil and natural gas reserves from both offshore deposits in the Caspian Sea itself and onshore fields in the region. Korchagin oilfield is located in the northern part of the Caspian Sea. Drilled wells are mega-reach (MD/TVD ratio greater than 3.0), with measured depths (MD) up to 23,622 ft and vertical depths of only 5,118 ft. This presents a great challenge for any well interventions, even for Coiled Tubing (CT) equipped with state-of-the-art hydraulic tractors. Limited working area, weight restrictions, challenging well geometry, completion features and lack of experience in offshore CT operations in the North Caspian Sea, required complex pre-job activities to optimize job design, select proper downhole tools and prepare a robust layout plan. This paper illustrates North Caspian project preparation challenges, on-the-job troubleshooting and workflow, supported by the well case studies and results from the first CT operation in North Caspian Offshore. Lessons learnt from the project, where all defined objectives were achieved with zero HSE (health, safety and environment) incidents, were also captured to assist in future campaigns with similar operational environment.
Авторское право 2014 г., Общество инженеров нефтегазовой промышленности Этот доклад был подготовлен для презентации на Российской технической нефтегазовой конференции и выставке SPE по разведке и добыче, 14 -16 октября, 2014, Москва, Россия.Данный доклад был выбран для проведения презентации Программным комитетом SPE по результатам экспертизы информации, содержащейся в представленном авторами реферате. Экспертиза содержания доклада Обществом инженеров нефтегазовой промышленности не выполнялась, и внесение исправлений и изменений является обязанностью авторов. Материал в том виде, в котором он представлен, не обязательно отражает точку зрения SPE, его должностных лиц или участников. Электронное копирование, распространение или хранение любой части данного доклада без предварительного письменного согласия SPE запрещается. Разрешение на воспроизведение в печатном виде распространяется только на реферат объемом не более 300 слов; при этом копировать иллюстрации не разрешается. Реферат должен содержать явно выраженную ссылку на авторское право SPE. РезюмеПовсеместное внедрение технологий многостадийного гидроразрыва пласта (МГРП) в России, помимо ожидаемых, приносит и незапланированные результаты. Кроме безусловного увеличения дебитов и прироста извлекаемых запасов, данная технология несет в себе и такую опасную тенденцию, как преждевременное обводнение скважин. Происходит это по ряду причин, среди которых, пожалуй, одно из основных мест занимает прорыв в водоносные горизонты при проведении самого гидроразрыва пласта (ГРП) одного или нескольких интервалов.Компанией-оператором была поставлена задача, провести водоизоляционные работы в горизонтальной скважине (ГС), законченной 8-стадийной компоновкой МГРП с расфрезерованными посадочными седлами. Для уточнения причин обводнения и локализации интервалов его поступления были проведены геофизические исследования скважины на гибкой насосно-компрессорной трубе (ГНКТ). В результате было выявлено, что в скважине при общем дебите жидкости более 500 м3/сут (данные, полученные при освоении) и 95% обводненности порт № 6 дает 68% от общего дебита, а остальные 7 портов работают с незначительными дебитами либо ниже уровня пороговой записи прибора.В данной статье подробно рассматриваются этапы планирования, решения сложных и нетиповых технических и практических задач, оценка нетиповых рисков и методы их снижения, этапы выполнения работы и вариативности действий в различных ситуациях, возникающих в процессе работы по водоизоляции, а также опыт, полученный в результате успешного выполнения данной операции. ВведениеЮжно-Выинтойское нефтяное месторождение расположено в Сургутском районе Ханты-Мансийского автономного округа Тюменской области. Месторождение было открыто в 1990 году, в 1997 году начата его разработка. По величине запасов Южно-Выинтойское месторождение относится к средним, по строению -к сложным.Основными проблемами разработки Южно-Выинтойского месторождения являются(1):слабая степень изученности объектов месторождения; клиноформное строение основного горизонта БВ, а также нер...
Korchagin oilfield is located in the northern part of the Caspian Sea. Drilled wells are mega-reach (MD/TVD ratio greater than 3.0) with measured total depth (MD) up to 23,622 ft [7,200 m] and vertical depth of only 5,118 ft [1,560 m]. This presented a great challenge for coiled tubing (CT) well intervention even with the help of state-of-the-art hydraulic tractors. Limited working area, weight restrictions, challenging well geometry, completion features and lack of experience in offshore CT operations in the North Caspian Sea, required complex pre-job activities to optimize job design, select proper downhole tools and prepare a robust layout plan. This paper will illustrate the project preparation challenges, on-the-job troubleshooting and workflow, supported by the well case studies and results from the first CT operation in Northern Caspian Offshore. Lessons learned from the project, where all defined objectives were achieved with zero HSE (health, safety and environment) incidents, were also captured to assist in future campaigns with similar operational environment.
Horizontal drilling and multistage fracturing completions are becoming widespread practices in the development of Western Siberia’s low-permeability oil fields. More than 100 wells have been completed to date—with success from both operational and production perspectives. The majority of applications were applied in newly drilled wells, where it is possible to install openhole packers and frac ports for isolating fracture stages. The concept of multistage fracturing was transferred to old areas of brownfields, where sidetracks drilling was the main method of increasing oil recovery. Traditional sidetracks were associated with risks of production underachievement in low-permeability environments - even after stimulation treatments. The ability to drill sidetracks with a considerable horizontal section, and stimulating them with several fracturing stages would improve production significantly. However, slim wellbores of sidetracks significantly restrict completion option choice and abrasive perforating via coiled tubing (CT) becomes a universal enabler for multistage fracturing treatments. One of the greatest challenges in such a process is isolation between the stages. Fiber-enhanced proppant plugs were used for better proppant grains suspension, which sets the plug in the most efficient, homogeneous way. The first well was recently completed with this method. Three stages of fracturing stimulation were performed with CT abrasive perforation; fiber-enhanced proppant plugs were placed at the tail-in of the first two fractures. In both of the fractures, reliable isolation was achieved at first attempt. After all three stages were placed, wellbore cleanout with CT was performed, followed by nitrogen kickoff. Oil production has exceeded expectation by 30%. Multistage fracture (MSF) stimulation in the horizontal section of a sidetrack well completed with cemented liner with the utilization of abrasive perforating and fiber-enhanced proppant plugs has demonstrated unique value, as it is the only effective solution currently available for these conditions. The decision-making and candidate-selection processes, execution and lessons learnedare described.
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