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Until recently, electric line tractor driving speeds have been lying significantly below their true potential, because of elements related to design, working principles and system dynamics. Several case histories from recent electric line tractor conveyance operations illustrate the number of operational benefits that have resulted from an engineering re-design, through applying the latest electronic and hydraulic technologies to electric tractor conveyance.
Electrohydraulic tractors were developed in the mid 1990s as an alternative means to convey electric line deployed tools along the highly deviated or horizontal sections of wells. The application of this tractor technology has grown considerably over the years, having been applied to convey an increasing range of technology payloads (for example, logging tools, ballistic devices and powered mechanical applications) to an expanding stock of deviated wells with increasing length and tortuosity. The performance and capability of electric line tractor tools has always been a trade-off between numerous limiting factors including the electric line cable (strength, weight, length, voltage and current rating), the surface power supply, the tractor components (downhole motor power and drive train efficiency), and the completion size into which it is deployed. This has until now necessitated tractor pre-set requirements to successfully perform a job, resulting in limitations on performance criteria such as tractor pull force and speed.
This paper discusses recent improvements to the tractor platform achieved through redesign and by applying new electronic and hydraulic developments which enable in-well, on-the-fly optimisation of the tractor components and parameters. The field operations demonstrate the transformation in tractor conveyance speeds achieved, in the order of three and a half times that previously delivered, representing a new standard in electric line tractor conveyance efficiency. These speeds, coupled with increased payload conveyance capability and the improved mission certainty which can be achieved, are even more relevant in wells of significant measured depth, lateral length and challenging well profiles and trajectory complexity.
The technology presented will also allow well completion engineers to plan complex well intervention jobs in demanding wells with more confidence now that it is available to increase operational success.
Almulla, Sulaiman (Kuwait Oil Company KOC) | Al-Bader, Haifa (Kuwait Oil Company KOC) | Al-Ibrahim, Abdullah (Kuwait Oil Company KOC) | Subban, Packirisamy (Kuwait Oil Company KOC) | Duggirala, Vidya Sagar (Kuwait Oil Company KOC) | Ayyavoo, Mani Maran (Kuwait Oil Company KOC)
The main objective is to find a way to increase the well production and sustain the production by connecting the reservoir through several stages of fractures spaced throughout the horizontal drain hole.
Exploratory wells targeting Mauddud reservoir were normally drilled vertically and stimulated in a conventional way using matrix acid treatment, which proved a good hydrocarbon potential, but with low productivity. A study was conducted in one the lower cretaceous reservoir (Mauddud) which recommended the option of drilling a horizontal well in the mentioned reservoir and applying multi-stage acid frac for productivity enhancement and sustainability. The target carbonate reservoir is tight, has a porosity of approximately 12-20% and permeability between 0.05 to 2 md. The first horizontal well for Maudddud reservoir was drilled up to a measured depth of 11,171 ft MD with a horizontal section of 2,752 ft. It was completed with swell packers and seven frac sleeves for multi stage fracturing job in the horizontal section. Designing and execution of multi-stage frac in a horizontal well is technically more challenging than the conventional vertical well.
Minifrac was performed to find the fracture pressure, closure pressure and understand the net pressure needed to extend the fracture. Based on the mini-frac results, the main frac design was modified. Main Frac treatment was carried out in seven stages, each stage was performed individually and the fractured stage was isolated using frac balls with different sizes. Acid and gel mixing was performed continuously on location to enable continuous pumping operation, which minimized the time between stages. After a successful multistage frac treatment, the well was flowed back for cleanup and recovered all spent treatment fluid. Later Coiled Tubing (CT) with milling tool was used to mill the ball and seats to provide full bore access through the frac sleeves. Subsequently production logging tool (PLT) survey was carried out in horizontal section using CT to confirm the effective contribution from each stage.
Horizontal exploratory well was drilled, completed and fractured successfully with seven stages led to a sustainable oil production after installing ESP. The flow results after the multistage frac showed that there is tremendous increase in production but with some decline. The PLT result showed the contribution profile for each stage and the cross flow status. Production enhancement and sustainability achieved from this well encouraged KOC to drill more horizontal wells for Mauddud reservoir with similar multistage completion and frac strategy to meet the production targets.
This paper highlights the well design, the effectiveness of multi stage fracturing, well performance analysis, lesson learned and results of the multistage completion & acid fracturing.
The drilling records of Extreme Reservoir Contacts (ERC) like Extended Reached Drilling (ERD) and Multi-Lateral wells(ML) continue to be broken. From the initial limit of MD 10,000ft to now almost 50,000ft with extended reach depths and from dual-lateral to quad-laterals’ with 40,000-50,000ft reservoir contact. Completions rule of engaging with this type of wells continues to play ‘catch-up’. As a result, getting the full potential out of these extreme wells with limited completions options had always been a challenge. Recent innovation in "wireless electric connect/disconnect" technology combined with all electric integrated intelligent completions architecture has addressed these challenges. The well completion design is an all electrical system that provides a multi trip connect/disconnect system enabling seamless communication between upper and lower completions enabling permanent downhole monitoring and control, at the sand face. The highlight of this digital edge solution and deployment architecture enables completions to deploy in ERC wells meeting targeted drilled depths and achieving reservoir goals. The digital enablement provides real time downhole data for permanent production logging and zonal well testing capability while producing. Production and reservoir management is at finger tips of the end user.
A new innovative down hole electric telemetry enabled data transmission and power to be distributed across multiple sensors like pressure, temperature, water cut and electric flow control valve. Run on a single electrical cable, this digital completion technology with its induction coupling capability continue to complete record-drilling wells and makes today's completions limitations a history. It is now a reality for fully-digitalized Intelligent Completions solution, which can support any well type scenarios; multi-zones, horizontals, multi-laterals and extended reached drilling (ERD), including subsea completions. Each zone can be equipped with a permanent downhole infinite position valve-control, flowmeter, water-cut sensor and/or pressure/temperature gauges. This allows real-time reservoir measurement and supports ‘Dial A Rate’ flow control. Conventional flow control valves depend on hydraulic actuation system, although the technology has worked for decades, it has some inherent limitations such as need for multiple control lines limiting the number of zones, maximum depth of deployment as well the response time of hydraulic systems for very long completions. Electric valves are free from these limitations by design and provides lot more flexibility in the hands of the completion engineer. The multiple sensors measurement and data integration is achieved with a single surveillance, monitoring, diagnostics and valve-optimization production software to ensure real time data streaming, management and bringing insights to production and reservoir engineers for production optimization through remote valve control.
This digital solution of Intelligent Completions technology can finally claim that completions is no longer the limiting factor, effective reservoir management with intelligent completions can follow wherever the drill bit can go. It has been deployed worldwide from the Middle East to the open Sea in Pacific to enable zonal production-control and reservoir management. Its borderless completions architectures and standardization of modular system is the answer for Digital Oilfield and Data driven continual production optimization and reservoir management without intervention.
For the first time in Completions history, extended drilling records are matched with completing the entire well to Measured Depth (MD) with fully digitized solution of multi-zone measurements, infinite-control valves and real time data enabled production optimization system.
Parfiryev, V. A. (Oil and Gas Production Department Talakanneft) | Zakirov, N. N. (Tyumen Industrial University) | Vaganov, Yu. V. (Tyumen Industrial University) | Paleyev, S. A. (Oil and Gas Production Department Talakanneft)
The PDF file of this paper is in Russian.
Today, the high-quality opening of productive formation during field development in Eastern Siberia is becoming the most urgent problem. The opening of the reservoir with saturated saline and the inability to use the arsenal of technologies used in the regions of Western Siberia to intensify the flow of wells such as hydraulic fracturing makes it necessary to increase the requirements for the drilling of productive horizons. The presence of anhydrite in the rock and its interaction with aqueous solutions significantly worsen the reservoir properties. In order to improve the quality of primary drilling and drilling of a productive horizon, a solution based on diesel fuel (CBM) was developed. Experimental industrial testing of this solution was carried out while drilling production wells at a field in Eastern Siberia. Drilling of intervals for liners in horizontal and directional wells using CBM went without complications. As a result of the pilot tests, the advantage of hydrocarbon-based solutions under these conditions was actually confirmed. The obtained well production rates when opening and drilling of the productive horizon was carried out at the CBM, are almost 2.5 times higher than the production rates of wells constructed by traditional technology using the saturated saline biopolymer drilling mud.
В настоящее время качественное вскрытие промышленных объектов при разработке месторождений в Восточной Сибири становиться наиболее актуальной проблемой. Вскрытие продуктивного пласта насыщенным солевым раствором и невозможность применения арсенала технологий, применяемых в регионах Западной Сибири для интенсификации притока скважин, таких как гидравлический разрыв пласта (ГРП) обусловливает необходимость повышения требований к процессу бурения продуктивных горизонтов. Наличие ангидрита в породе и взаимодействие его с водными растворами значительно ухудшают фильтрационно-емкостные свойства пласта. С целью повышения качества первичного вскрытия и бурения продуктивного горизонта разработан раствор на основе дизельного топлива (раствор на углеводородной основе). Проведены опытно-промысловые испытания данного раствора при бурении эксплуатационных скважин на месторождении в Восточной Сибири. Бурение интервалов под хвостовики в горизонтальных и наклонно направленных скважинах с применением раствор на углеводородной основе прошло без осложнений. В результате опытно-промысловых испытаний фактически подтверждено преимущество растворов на углеводородной основе в данных условиях. Полученные дебиты скважин, в которых бурение и вскрытие продуктивного горизонта проводилось с использованием раствор на углеводородной основе, практически в 2,5 раза превышают дебиты скважин, построенных по традиционной технологии с применением насыщенного солевого биополимерного раствора. Разработанный раствор на основе дизельного топлива сохранял приемлемые реологические свойства в условиях низкой пластовой температуры (10 °С) и высокую электростабильность. Наличие выбуренной породы в объеме раствора не влияло на реологические параметры в системе, значения пластической вязкости, динамическое и статическое напряжения сдвига оставались стабильными, несмотря на загрязнение раствора. Показана возможность повторного использования раствор на углеводородной основе, что позволит значительно снизить затраты на приготовление раствора.
Al-Enezi, Badriya (Kuwait Oil Company) | Liu, Peiwu (Schlumberger) | Liu, Hai (Schlumberger) | Kanneganti, Kousic Theja (Schlumberger) | Aloun, Samir (Kuwait Oil Company) | Al-Harbi, Sultan (Kuwait Oil Company) | Al-Ibrahim, Abdullah (Kuwait Oil Company)
A recent study showed that Tuba reservoir, a limestone-rich formation, has the highest oil in-place of all upcoming reservoirs in North Kuwait. This tight formation has three main layers - Tuba Upper (TU), Tuba Middle (TM), and Tuba Lower (TL) with several reservoir units alternating with non-pay intervals. The reservoir units contain significant proven oil reserves; however, production performance after conventional acid fracturing treatments has been historically subpar. As part of new development plan, two horizontal wells, one in TU and one in TL were drilled to evaluate the production potential of a new completion strategy and technologies.
This paper presents one such technology, a single-phase retarded acid system used as a pilot project study. In contrast with previous conventional emulsified acid systems, the single-phase retarded acid minimized tubing friction, thus enabling high pumping rates for the entire treatment. Alternating with the acid system, a viscoelastic surfactant-based leakoff control fluid system allowed the acid stages to reach deeper into the formation. To aid, degradable fiber technology was pumped in several stages to achieve near-wellbore diversion and further control leakoff into large natural fractures, thus improving the stimulated reservoir volume. These fibers are designed to completely degrade with time and temperature after the treatment. Delivery of the complex acid fracturing treatment was optimized in real time for each stage based on bottomhole pressure trend and response.
Combining a new single-phase retarded acid system with chemical diversion technology has proved to be effective in maximizing lateral coverage and etched fracture half-length. Post-treatment evaluation of TU horizontal well revealed the initial production was as much as 150% higher than offset vertical wells after conventional treatments with gelled acid and as high as 100% higher than a previous multistage horizontal well treated with emulsified acid. The TL horizontal well was just put into production recently and is showing encouraging results considering the lower reservoir quality compared to TU formation.
The success of this technique and technical combination delivered breakthrough results for this region and has engaged new interest in developing the Tuba reservoir.
Shestakov, Dmitry (Kogalymneftegaz TME LUKOIL-West Siberia LLC) | Galiev, Marat (Kogalymneftegaz TME LUKOIL-West Siberia LLC) | Badrtdinov, Ilshat (Kogalymneftegaz TME LUKOIL-West Siberia LLC) | Khamidullin, Vadim (Kogalymneftegaz TME LUKOIL-West Siberia LLC) | Ovchinnikov, Kirill (Geosplit LLC) | Malyavko, Evgeny (Geosplit LLC)
The present article highlights a new approach to solving objectives aimed at efficient and rational development of oil and gas fields based on conducted production logging of Kogalymneftegaz TME, LUKOIL-Western Siberia LLC horizontal wells with the application of marker-based technology Quantum PLT.
Well logging technology using markers is based on the application of quantum marker-reporters precisely indicating oil and water inflows. The placement of markers in the well implies two alternative technological solutions – application of marked proppant during MFrac or application of downhole cassettes with markers installed in the lower completion of the horizontal well. The advantages of the technology involve no necessity of well shut-in during downhole operations and the possibility to obtain an unlimited number of analytical data for a long period of time.
Marker-based technologies produced by different manufacturers differ in physical principles of operation, as well as in the methods of markers placement in the well or reservoir. The results of two alternative marker-based systems application in one well are shown in this article. This approach allowed us to compare the results and to evaluate the advantages and disadvantages of these two technologies. The well was completed by MFrac with the possibility of further ports control with the application of coiled tubing service. Each of five well intervals was equipped with two marker cassettes fixed on both sides of the MFrac port. Three months later MFrac with pumping marked proppant was performed on the well.
As a result of the world-first field application of alternative marker-based systems, valuable analytical material was obtained on the quantitative analysis of various markers, the performance of different polymers, the stability of the markers allocation in the formation fluid. The data obtained confirmed the character of the marked proppant pack washing out with the formation fluid in comparison with cassettes with markers.
Moreover, the efficiency of conducted stimulation was evaluated, specific horizontal well inflow profile types were identified, the degree of the reservoir management system impact on the inflow profile was evaluated.
It has been demonstrated, that received analytical data based on horizontal wells production logging enable addressing the issues of field digitalization at a totally new level, including: visualizing recovery in hydrodynamical models; control of hydrocarbon recovery, also by improving water flooding efficiency and better management of injection wells; efficient planning of well intervention and stimulation techniques; optimization of horizontal sections length and the number of MFrac ports; adapting the relevant geological and hydrodynamic models considering analytical data related to production logging data, etc.
visualizing recovery in hydrodynamical models;
control of hydrocarbon recovery, also by improving water flooding efficiency and better management of injection wells;
efficient planning of well intervention and stimulation techniques;
optimization of horizontal sections length and the number of MFrac ports;
adapting the relevant geological and hydrodynamic models considering analytical data related to production logging data, etc.