This paper describes the application of openhole Multi-Stage Fracturing completions with swelling packers and sliding sleeves in the carbonate formation of the Karachaganak field, Kazakhstan. It focuses on the benefit brought to the field by the new completion concept. It also explains the methodology and strategies adopted for executing fracturing stimulation within the limited capacity of material supply and logistic challenges in a harsh environment and remote location. The completion strategy in the Karachaganak field has been evolving from simple vertical (cased hole / openhole) completions, to selective and non-selective multilateral wells, and most recently to extended horizontal wells. Acid stimulation, both matrix and fracturing, are the common method to improve well productivity in this highly heterogeneous formation. Multi-stage acid fracturing was identified as a potential technique to achieve the objective of unlocking production from extended horizontal openhole section in the low permeability regions of the field. The new completion technology combines the use of swelling packers and ball activated stimulation sliding sleeves (with a mechanical shift option) to achieve intervention-free multi-stage fracturing in the openhole. The swelling packer and stimulation sliding sleeve provide a reliable isolation and fracturing point respectively for a selected fracturing zone. Post-stimulation inflow profile indicated contribution from almost all the treated zones as a result of diversion effectiveness. The first application of this technology in one of the Karachaganak wells resulted in a significant initial production and the well was recorded as one of the best Object 3 oil producers in the field. Ten (10) subsequent completions were deployed after the first installation. The stimulations performed to date have shown that Swelling Packers are reliable for zonal isolation and allow a good coverage of the entire horizontal section.

Karachaganak is a gas condensate field in western Kazakhstan's pre-Caspian basin. The reservoir is a heterogeneous carbonate rock. Oil-based fluids are not extensively employed in stimulation due to their costs. The paper's objective is to describe the issues the operator faced and that led to the field trial of an oil-based stimulation fluid, fluid selection process and the results of the successful application of this technology as a cost-effective means of improving Karachaganak stimulation operations. KPO finds horizontal wells completed with multi-stage stimulation sleeves isolated with swell packers installed in 6″ open hole as most suitable and efficient method of construction of oil production wells in the Karachaganak field. However, stimulation of wells such as these creates the potential for injection of large volumes of water into the formation which can result in lengthy well cleanups. To provide a solution to this problem KPO instigated a field trial of an oil-based fluid in stimulation. Water-based linear gel, used as a displacement fluid, comprises the largest part of pumped water volumes. Therefore, replacing gel with an oil-based system would lead to a drastic reduction in the amount of water injected. In the course of a close collaboration with the Service Company, an oil-based stimulation displacement fluid was selected basing on laboratory testing that considered the effect on both the formation and the surface production facilities. A successful field trial then followed that showed reduced clean-up time (and, consequently, reduced greenhouse gas emissions), potential cost savings, and accelerated production. KPO then continued with the use of the oil-base fluid system, and the results of the trial were replicated. The success of the operations shows there is potential to further optimize the nature of stimulation fluids with the intent to decrease injection volumes. In addition, a market investigation of alternative base fluids is currently in progress with the aim of further reducing cost while still continuing to get the benefits resulting from the use of oil-based stimulation fluids.

New wells in KPO are completed as multistage frac completions utilizing up to ten stimulation sleeves activated by a ball landed in a respective seat (called a baffle) installed inside the sleeves. The objective since the beginning was to mill balls and baffles in the horizontal section improving the safety of the operation while minimizing volume of fluid injected, execution time, costs, and clean-up time. The initial approach was to use coiled tubing. Using coil to mill balls and baffles was not optimal, as the milling performances were difficult to replicate well after well. Additionally a significant amount of fluid was injected into formation together with some debris causing formation damage and making clean-up a long and costly process. An alternative option of milling utilizing robotic technologies was investigated as a viable solution for improving our performance. Therefore, the experience gained by KPO on milling with tractor in multistage frac completion is unique worldwide, and did add a lot of value to the wells delivered to production. This paper describes the evolution and modification done to tractor milling approach, particularly: Yard tests performed before implementing the operation in the field. No field deployment application took place before yard test outcomes were completely satisfactory.Results of the tests and modifications done to the tools as a result of the tests performed in the yard.Performance during field job execution, lessons learnt during each application, and how those lessons learnt influenced design modification of the tools and milling methodology. Thanks to a close collaboration established between KPO and Welltec, all objectives were accomplished with repeatable performance. Recently, up to nine balls and baffles corresponding to the entire horizontal section have been milled with a tangible benefit in terms of production, reducing clean-up time and emissions and improving safety. Even though the initial target was achieved, KPO believes there is still room for improvement and optimization. This will be done in the near future following further dedicated yard tests with positive results.

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Авторское право 2015 г., Общество инженеров нефтегазовой промышленности Этот доклад был подготовлен для презентации на Каспийской Технической конференции и выставке SPE, 4 -6 ноября, 2015, Баку, Азербайджан.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. Краткое изложениеЭлектрогидравлические роботизированные инструменты, которые выполняют ГТМ на электролебедке (e-line), разработаны 10 лет назад и на сегодняшний день используются для выполнения работ, ранее осуществляемые с использованием НКТ и/или ГНКТ. Примерами таких работ являются фрезеровочные работы, манипуляции циркуляционных клапанов (ЦК), и т.д.Наземный контроль параметров в реальном времени и средства управления необходимы, чтобы удостовериться, что работы подобного рода, выполняемые роботизированными инструментами, выполняются с высокой точностью. По мере увеличения спроса на использование такого вида прибора в более неблагоприятных скважинных условиях сервисные компании усовершенствовали свои технические возможности.Начиная с конца 2013 года робототехника использовалась в горизонтальных скважинах КПО с высоким содержанием сероводорода, чтобы закрыть ЦК при необходимости для контроля пластовой жидкости, спуска перфораторов, каротажных приборов и для разбуривания шаров и посадочных гнезд ЦК, используемых при ГРП.В данной статье представлены 4 варианта применения робототехники на Карачаганакском промысле. Также будут приведены преимущества и недостатки технологии, и дальнейшие усовершенствования, необходимые для оптимизации промысловых работ.