The electromagnetic heating of oil wells and reservoirs refers to thermal processes for the improved production of oil from underground reservoirs. The source of the heat, generated either in the wells or in the volume of the reservoir, is the electrical energy supplied from the surface. This energy is then transmitted to the reservoir either by cables or through metal structures that reach the reservoir. The main effect, because of the electrical heating systems used in practice in enhanced oil recovery, has been the reduction of the viscosity of heavy and extra heavy crudes and bitumens, with the corresponding increase in production. Focus is centered on systems (and the models that describe their effects) that have been used for the electromagnetic heating in the production of extra heavy petroleum and bitumen.
Mohammed, Noor (Kuwait Oil Company) | AL-Rashidi, Hamad (Kuwait Oil Company) | Safar, Abdul-Aziz (Kuwait Oil Company) | Duncan, Bruce (Kuwait Oil Company) | AL-Sagheer, Asmaa (Kuwait Oil Company) | Muhsain, Batoul (Kuwait Oil Company)
Kuwait has started developing the heavy oil fields in deep wells as part of a national oil production strategy and KPC strategy 2040, in order to maintain its increasing oil production capacity for the next decade. The recovery of heavy oil needs a particularly high level of expertise, optimum technologies and techniques, which are tailored to the distinctive challenges presented with consideration to detailed economic analysis and evaluation.
There are several wells perforated in the desired reservoirs within the potential study area which is under secondary (Progressing Cavity Pump) and natural production phase. The low productivity from oil producers which are completed in Lower Burgan sand which is characterized by very high viscous crude oil around 15,000 cp, a low gas-oil ratio (10-30) with little or no primary drive mechanisms. The project requires that certain challenges must be overcome the following key challenges are identified as: Limited mobility due to high viscosity of the oil. Absence of typical drive support associated with dissolved gas, deep well, and oil with compositional gradient reservoir. Non-thermal well completion, perforation design policy. Lack of fluid/rock characterization and oil-wet system.
Limited mobility due to high viscosity of the oil.
Absence of typical drive support associated with dissolved gas, deep well, and oil with compositional gradient reservoir.
Non-thermal well completion, perforation design policy.
Lack of fluid/rock characterization and oil-wet system.
In the design of this project, the suggested method to be used is a non-thermal optimization process "chemical treatment ". Chemical treatment will be implemented as a technology for a well that stopped producing in 2013. This method has been applied globally and has been proven it has less impact on the environment as per KOC HSE policy. The selected environmentally friendly method has three important mechanisms, which are: Wettability alteration agent. Viscosity reducer agent. Asphaltene inhibitor agent.
Wettability alteration agent.
Viscosity reducer agent.
Asphaltene inhibitor agent.
KOC has successfully conducted a pilot on 20th October 2016 and the well was put back on to the production phase at almost 300 bbl/day (net oil). The return of investment (ROI) of this pilot was a key calculation in answering the economic question and validating the project. As well as showing the project value and its impact on the margin. The return of investment (ROI) captured within 4 hours of production and the total profit to date is 438,885.52 USD.
Cuevas, Nestor (Schlumberger) | El-Emam, Adel Hassan (Kuwait Oil Company) | Al-Jenaie, Jarrah (Kuwait Oil Company) | Hafez, Mohamed (Kuwait Oil Company) | Ceci, Federico (Schlumberger) | Pezzoli, Mauro (Schlumberger)
Numerical studies are presented to evaluate the sensitivity of surface and surface to borehole Controlled Source Electromagnetic (CSEM) methods, to monitor the evolution of a steam plume injection in EOR for the Ratqa heavy oil reservoir, in North Kuwait.
A surface CSEM dataset collected over a pilot area in 2011 was used to determine a baseline 3D model of electrical resistivity at reservoir depth. To this end, the data underwent constrained 3D inversion, incorporating a-priori information from resistivity well logs and seismic horizons and focusing the inversion within the reservoir. The resulting 3D model provided high resolution of the lateral and vertical distribution of electrical resistivity within the reservoir, which was further verified by comparison with direct interpolation of well log data available over the entire area of the survey. Perturbations of the reservoir resistivity were then introduced by arbitrarily lowering the resistivity in a thin disk defined around a test wellbore, such as to represent a steam plume homogeneously expanding away from the borehole. Datasets were then numerically simulated to determine the expected response of EM measurements performed by surface deployed receivers and excited by sources deployed both on the surface and in the borehole, within the reservoir section. It was found that surface CSEM data could be used to recover the resistivity anomaly produced by the steam injection, provided that the injected steam generates a plume with a radius > 60. Smaller plumes produce a surface response which was close to the measurement's noise level expected in a 4D time-lapse survey. A STB-EM configuration was found to yield a strong sensitivity of the response even for radius of the plume < 20m.
At the outset the analysis presented here shows that resolution of surface based deployments is low, but they can be used to determine large scale variations within the reservoir. Novel and recently developed STB-EM technologies can yield the resolution required of the length scales variations expected in EOR processes.
Because of this, is considerable value in sharing knowledge and ideas to help overcome these challenges with tracers. The goal of this session is to discuss the challenges and opportunities of the tracer technology in thermal recovery and unconventional resources. Because of this, is considerable value in sharing knowledge and ideas to help overcome these challenges with tracers. When you attend an SPE event, you help provide even more opportunities for industry professionals to enhance their technical and professional competence. Scholarships, certification, the Distinguished Lecturer program, and SPE's energy education program Energy4me are just a few examples of programs that are supported by SPE.
In this paper, we divide the steps to explore, identify, and monitor a SAGD site into six stages and show how electromagnetic methods can be used at each stage. Three-dimensional inversion of airborne EM data provide large-scale, regional geologic trends and delineate paleo-channels and the caprock thickness at a newly-developed property in the Athabasca oil sands. We use semi-synthetic models from resistivity logging and the airborne data in conjunction with ground-based and borehole EM surveys to characterize the oil-rich McMurray Formation and monitor steam chamber growth over time. Periodic EM data collection and three-dimensional time-lapse inversion allow for high-resolution interpretations throughout the SAGD process.
Presentation Date: Wednesday, October 19, 2016
Start Time: 4:00:00 PM
Presentation Type: ORAL
The pdf file of this paper is in Russian.
Over the past decades, high-viscosity and heavy oil fields have been explored and put on stream. Generally, these oils have viscoplastic properties due to high-molecular-weight components, such as resins and asphaltenes. This paper presents some aspects of producing oils that behave like non-Newtonian fluids. Based on the analysis of crude oil rheology in Tatarstan fields, interpretation technique has been developed for the available data to be used in reservoir simulators. This paper reviews various fluid types and analyzes viscosity versus shear rate. It is concluded that in reality, fluids often demonstrate pseudo-plastic characteristics with yield limits, and require more complicated equations to characterize their flow behavior, compared to Newtonian fluids. By the example of Bobrik horizon, the Melninsky field, pressure differentialviscosity relationship has been identified wherein simulated cutoff values of these parameters yield a 5% error, compared to the case without regard to oil viscoplastic properties. Numerical studies prove the necessity of considering the structural and mechanical oil properties. When modeling oil fields where these properties are well-pronounced, pressure gradient distribution maps should be used based on isobar maps to identify the most promising areas for reservoir stimulation operations, including infill drilling, reservoir pressure maintenance, and formation heating. Optimization of reservoir pressure maintenance system and denser well spacing pattern increase sweep efficiency and maintain pressure differential required for heavy oil flowing while providing a larger radial extent of the reservoir. Formation heating reduces the effect of viscoplastic properties in the zones with low oil mobility.За последние десятилетия разведаны и введены в разработку месторождения нефти повышенной и высокой вязкости. Нефть данного класса, как правило, обладает вязкопластичными свойствами вследствие содержания таких высокомолекулярных компонентов, как асфальтены и смолы. Исследованы некоторые аспекты разработки нефтяных месторождений, нефть которых проявляет свойства псевдопластичной жидкости. По результатам исследования реологических свойств нефтей на месторождениях Татарстана представлена методика интерпретации имеющихся данных для использования в гидродинамических симуляторах. Рассмотрены типы жидкостей и выполнен анализ зависимостей вязкости от скорости сдвига. Выявлена зависимость градиента давления от вязкости на примере бобриковского горизонта Мельнинского месторождения. При предельных значениях вязкости в расчетах погрешность составляет 5 % по сравнению с вариантом без учета пластичных свойств нефти. Показана необходимость учета структурно-механических свойств нефти. Для таких месторождений, в которых эти свойства проявляются достаточно выраженно, необходимо использовать карты распределения фактических градиентов давления на основе карт изобар с выделением перспективных участков для внедрения методов воздействия: уплотнение сетки, поддержания пластового давления (ППД), прогрева пласта. Оптимизация системы ППД и использование более плотной сетки скважин позволяет увеличить охват пласта воздействием и поддерживать достаточный перепад давления для фильтрации нефти с вязкопластичными свойствами при более высоком радиусе воздействия. Прогрев пласта позволяет уменьшить влияние вязкопластичных свойств в областях движения нефти с незначительной скоростью.
Gauging oil and water rates from heavy oil wells has historically been a difficult task. Heavy oil offers several unique problems that hinder that task. These include oil density close to the associated water density which hinders gravity separation, high viscosity which inhibits flow and proper instrumentation function, high sand production with bad implications for well testing facilities, and a tendency to form difficult oil/water emulsions. An automatic well test (AWT) system has been developed over time to overcome the problems associated with gauging thermal, heavy oil wells. This system selects a well from a group of wells with a valving system operating in hot/cold, high/low viscosity, sandy conditions and employs a test vessel that can handle high/low gross/net, sand, variable temperature, and gas if present. Tests with this system are not only reliable and much cheaper; they are done much more frequently.
When compared with steam-assisted gravity drainage (SAGD) operations in the McMurray Formation, Athabasca Oil Sands, SAGD projects in the Clearwater Formation at Cold Lake did not perform as expected, likely because of reservoir properties. This paper will use the Orion SAGD case study to: (1) investigate the impacts of reservoir properties on the SAGD thermal efficiency by field evidences; (2) identify key geological parameters influencing each well pad; and (3) summarize major geological challenges for Orion SAGD expansion.
Wireline log data were interpreted to characterize reservoir properties, which were used to build 3D models. 3D visualizations and 2D cross sections of the reservoir revealed spatial distribution and heterogeneity of each property. SAGD production performance was analyzed using: (1) temperature profiles that monitored the growth of the steam chamber; (2) cumulative steam-oil ratios (CSORs); and (3) oil production rates (OPRates), which are direct indicators of thermal efficiency.
Results show that impermeable barriers and low-permeability zones were detrimental to steam injectivity and steam chamber growth, as observation wells in Pilot Pads 1 and 3 did not detect any steam saturation. High-permeability zones favored high steam injectivity and mobility, especially in Pad 105. Steam chambers were irregularly shaped by high shale-content zones, as two sharp spikes displayed on the temperature profile in Pad 103. Low oil-saturation zones and thin net-pays increased the CSORs, as seen in Pads 106 and 104. Impermeable barriers are almost horizontal, making no difference on well pad orientation by their dip angles. Lack of porosity variation made it difficult to identify the impact of porosity on each well pad.
The relatively extensive distribution of impermeable barriers between and above well pairs, as well as the relatively large area of low oil saturation and thin net-pay, were identified as major geological challenges.
Heterogeneity in the Athabasca oil sands can impede the growth of SAGD steam chambers. Here, we show how controlled-source electromagnetic (EM) methods can be used to detect growth-impeded regions and monitor changes in steam chamber growth. Our achievements are two-fold. We first generate a background resistivity model based on well logging at a field site in the Athabasca oil sands and then estimate the resistivity of the steam chambers using an empirical formulation that incorporates the effects of temperature on the surrounding rocks. Using the resulting 3D model, electromagnetic responses for any EM survey can be computed. The second, and more important, achievement illustrates that imaging SAGD chambers, as they grow in time, may be possible with cost-effective surveys. Our example uses a single transmitter loop with receivers in observation wells. In the wells, only the vertical component of the electric field is measured. Even with this limited data set, the images obtained through 3D cascaded time-lapse inversion identifies the location and extent of an impeded steam chamber. The proposed EM survey acquisition time and processing should be relatively fast and cost effective, and are expected to yield sufficient information to help make informed decisions regarding SAGD operations.
Steam Assisted Gravity Drainage (SAGD) is an in-situ recovery process used to extract bitumen from the Athabasca oil sands in northeast Alberta. In SAGD, two horizontal wells are drilled at the bottom of the reservoir (Dembicki, 2001). Steam is injected into the top well and produces a steam chamber that grows upwards and outwards. At the edge of the chamber, the heated, fluid oil and condensed water flow through the formation and are collected by the underlying horizontal production well. The chamber expands further into the bitumen reservoir as the oil drains (Butler, 1994).
The success of this technique is dependent upon steam propagation throughout the bitumen reservoir. However, reservoir heterogeneity, such as clay beds and mudstone laminations, can cause low-permeability zones that can impact the growth of the steam chambers (Strobl et al., 2013; Zhang et al., 2007). This affects the amount of produced oil and exemplifies the importance of monitoring the steam chamber growth. Successful monitoring can aid in optimizing production efforts by increasing understanding of the reservoir, decreasing the steam-to-oil ratio, locating missed pay, identifying thief zones, and more efficiently using resources (Singhai and Card, 1988).
Because the electrical conductivity of a lithologic unit is affected by steaming, electric and electromagnetic methods are promising tools to detect and image SAGD steam chambers. Additionally, these types of surveys can be much more cost-effective than seismic methods (Engelmark, 2007; Unsworth, 2005). Electric and electromagnetic surveys can also be readily installed as permanent installations. Tøndel et al. (2014) used a permanent electrical resistivity tomography (ERT) installation in the Athabasca oil sands to monitor SAGD steam chamber growth over time. From their study, electrodes can stand up to the high-temperature environment in boreholes surrounding the steam chambers while geophones can break down over time. Devriese and Oldenburg (2015) showed how the method can be extended to frequency- and time-domain EM. Permanent installations can also provide multiple data sets per year, without being limited by access to the area in wintertime only.
Park, Changhyup (Kangwon National University) | Choi, Jiyeon (Kangwon National University) | Lee, Changsoo (Kangwon National University) | Ahn, Taewoong (Korea Institute of Geoscience and Mineral Resources) | Jang, Ilsik (Chosun University)
This paper determined the optimum operations of steam assisted gravity drainage covering steam interference between vapor chambers in a heterogeneous oil-sands deposit. The objective value was the minimum cumulative steam to oil ratio that represented energy efficiency. Three wellpairs, i.e. six horizontal wells, were installed to take steam interference between the chambers into consideration. The optimum operations showed the small difference of bottom hole pressure between an injector and a producer that released a small amount of steam into the reservoir. The lower injection could decrease the steam interference and lateral fluid movement by generating a similar size of chamber. A sensitivity analysis showed the key factors to cumulative steam to oil ratio were bottom hole pressure of the injectors and surface steam rate at the producers. To satisfy the limit of surface steam rate at the producer, the bottom hole pressure at the producer increased sharply and maintain the small difference between the producer and the injector.