In this paper, we present for the first time, a classification system for naturally-occurring gas hydrate deposits existing in the permafrost and marine environment. This classification is relatively simple but highlights the salient features of a gas hydrate deposit which are important for their exploration and production such as location, porosity system, gas origin and migration path. We then show how this classification can be used to describe eight well-studied gas hydrate deposits in permafrost and marine environment. Potential implications of this classification are also discussed.
Gas hydrates reservoirs are a type of unconventional reservoir that is an extremely abundant and ubiquitous source of energy. They are also relatively cleaner than most other hydrocarbon sources which makes them an even more attractive source of energy. The potential of this source of energy has, however, not been utilized since very little production has ever taken place from these reservoirs due to their complexity. This research provides an understanding of gas hydrates thermodynamics and reservoir properties in order to assist in properly modelling the hydrate flow in porous media. The research also provides a road map to the current production methods that have been used in pilot tests in order to produce from gas hydrates reservoirs. The production methods explained include depressurization, thermal stimulation, inhibitor injection, combined methods, carbon dioxide injection, and mining. The mechanism of each method is fully explained, and the advantages and disadvantages of each method are also explained. Several case studies worldwide are also discussed to show how each production method has been used to produce from the gas hydrate reservoirs. The results from the case studies are also used to reach conclusions on how each method can be improved upon. To the author’s knowledge, no publication has provided a complete overview on gas hydrates and their production mechanism which makes this research a crucial step in providing an overview on many aspects of gas hydrates reservoirs and their production mechanisms and potential. Understanding the mechanisms to produce from gas hydrate reservoirs is a crucial step in the hydrocarbon industry to allow us to tap into this vast source of energy in the near future.
With the current increase in demand on hydrocarbons, production from unconventional reservoirs has become extremely high. One of the most abundant, yet still not mass produced from, unconventional reservoirs is gas hydrates. This research investigates the applicability of steam injection in increasing gas recovery from gas hydrate reservoirs, and its impact on water production from gas hydrate reservoirs. The reservoir model was built based on data collected from previous models found in the literature. After specifying all parameters for the reservoir, and the hydrate layer, a systematic study was performed in order to assess the use of steam flooding as the primary hydrate production mechanism. The production methods studied include depressurization as the base case, and then steam injection. The conditions for the steam flooding were kept the same during all runs in order to be able to compare them. Results indicated that the use of the thermal stimulation alone without inhibitor managed to increase recovery, however, the problem of hydrate reformation occurred which caused a cessation of production. Also, water production increased significantly when using steam injection compared to depressurization, mainly due to the rapid hydrate dissociation during steam injection, and also due to the increased volume of water resulting from the injected steam. To the authors’ knowledge, no extensive study has been performed on using steam injection as the primary hydrate production mechanism, and assessing its impact on increasing water production form gas hydrate reservoirs. This research can help in improving real field gas hydrate projects by making the overall project much more economic by increasing hydrocarbon recovery.
Pilnik, Sergey (Gazpromneft-Yamal) | Dubrovin, Andrey (Weatherford) | Zimoglyad, Mikhail (Gazpromneft-Yamal) | Bulatov, Fuat (Gazpromneft-Yamal) | Burkov, Fedor (Gazpromneft-Yamal) | Abaltusov, Nikolay (Weatherford)
The key opportunity of Novoportovskoye Field is hydrocarbon reserves, which remain undeveloped. In this field, significant oil reserves directly underlie massive gas caps. Economic efficiency in such geological conditions is based on the use of new technologies for the maximum extension of field infrastructure loading.
This paper reviews prerequisites and cases of multilateral well drilling technologies as an efficient EOR method at Novoportovskoye Field. The paper summarizes the results of drilling of nine multilateral wells.
The strategy of multilateral well completion at Novoportovskoye Field increased the level of complexity defined by technology advancement for multi-laterals (TAML). First, a multilateral well with an openhole lateral was drilled. This openhole section collapsed when the well was brought into production at the target drawdown. Therefore, the second stage was to construct a multilateral well with cased main bore and lateral using TAML-1 technology.
A version of TAML-1 technology developed by a Russian manufacturer was adapted and implemented at this stage.
Several sidetracking methods were tested to reduce the rig time and multilateral well construction costs. Application of rotary steerable systems (RSS) for sidetracking instead of conventional rotary assemblies and downhole motors enabled to reduce the average sidetracking time from 70 to 30 hours. The record time of sidetracking using RSS was 16 hours.
The history of Novoportovskoye Field development demonstrates a continuous trend towards increasing horizontal section lengths from 1,000 to 1,500 and 2,000 meters. The cumulative multilateral well drilling experience enabled construction of a well with four laterals with a total length of horizontal sections of 4,411 meters. It was the first well with four laterals in Russia built according to TAML-1 technology.
As compared to conventional horizontal wells, the highest initial incremental oil rates were registered in multilateral wells drilled in the Jurassic Yu2-6 interval and the Cretaceous NP2-3 interval of the Novoportovskaya Formation. Considering that the share of the Yu2-6 interval in the oil reserves of Novoportovskoye Field is 46% and the share of the NP2-3 interval is 17%, the operator decided to increase the share of multilateral wells to develop these intervals.
The project objective for 2018 - 2020 is to increase the number of cased holes, to separate laterals to the maximum possible distance, and to improve the completion level to TAML-4.
There is not enough experience of hydraulic fracturing on unconsolidated low-temperature shallow formations, similar to the main development site of the East Messoyakhskoye field - PK1-3, was found in Russia. Test fracturing was performed on directional and vertical wells in the pilot works in 2017 and the main conclusions were drawn:
Approve technological capability of hydraulic fracturing on unconsolidated and high-permeability heavy oil reservoir
Approve creating traditional vertical fracture by geophysical methods and by the results of production
Value of fracture height by different methods of mapping fracture geometry are semi-comparable, which makes it possible to estimate the averaged value of each parameter
Performed complex of geophysics logging allows to estimate in technological efficiency of hydraulic fracturing
Performed complex of laboratory studies of various chemical compound hydraulic fracturing fluids on the core material made it possible to select the optimal compound with minimal negative impact on the formation
Step-by-step method increase of the aggressiveness of the treatment designs allowed the accident-free implementation of pilot works and estimate of possible aggressiveness to tip screen out (TSO)
The productivity gains resulting from the development and operation of the wells after the fracturing allow to adapt the result to the MHF in horizontal wells with the expected productivity gain of 40%
Limite fracture height growth is achieved by planning the optimal injection design, but it is not always possible. If gas-oil contact is near, it is difficult to control the geometry of the fracture, which led to the limitation of replicating the fracturing in water-oil zones without gas cap.
This article describes experience and results of TAML-3 penta-lateral (5-lateral) Fishbone type well construction at East-Messoyakha field. Trial work has been conducted to determine technical and economical feasibility of fishbone well construction.
East - Messoyakha field has very complex geological structure. According to field sedimentary conditions there are 3 major deposition cycles in primary PK 1-3 formation
Hydrodynamic modelling has shown multilateral well technology to be perspective in terms of increase of vertical association coefficient. Utilization of multilateral well technology is very perspective in geological conditions of East-Messoyakha field, it will also increase efficiency of reserves development compared to conventional horizontal wells.
During completion concept selection and planning stage, different options have considered. TAML-3 level have been selected for a multilateral junction. Lateral trajectories well paths were planned to cross sub-layers and turn in azimuthal direction.
Multilateral ERD well construction required multiple technical solutions to be implemented in order to successfully complete the project: running 7" casing in 800 horizontal section, utilization of OBM and its re-use, running lateral liners in two trips.
Successful project execution of penta-lateral allows to solve the following challenges:
extend reservoir coverage and increase of effective well radius in heterogeneous layers
simultaneous drainage in different layers
decrease the risk of production loss due to lateral hole collapse
Cased fishbone multilateral well proved its effectiveness after 6-months production. It is also a logical continuation of company’s technological development. The paper also discusses possible options for further advancement.
Digital technologies have a huge impact on our everyday life, including manufacturing industry, becoming a foundation for operations of large enterprises and corporations. Digital age offers unlimited opportunities while specifying rigorous requirements. Being essential for national economy oil and gas industry is not an exception: easy-to-reach oil is running low, hydrocarbon production is getting more accurate and science-based at all stages. It is necessary to search for different creative ways by using latest technologies to take the lead. Industry leaders create entire structures which provide analytical and scientific support of oil production and oil processing at all levels of manufacturing.
Zagrebelnyi, E. V. (Messoyachaneftegas JSC, RF, Tyumen) | Belozerov, B. V. (Gazpromneft NTC LLC, RF, Tyumen) | Bochkov, A. S. (Gazpromneft NTC LLC, RF, Tyumen) | Mishina, D. O. (Gazpromneft NTC LLC, RF, Tyumen) | Reshetnikov, D. A. (Gazpromneft NTC LLC, RF, Tyumen) | Kovalenko, I. V. (Gazpromneft NTC LLC, RF, Tyumen)
The PDF file of this paper is in Russian.
The Messoyakha project is one of the priority plans of Gazprom Neft Company, exploration of which provides significant incremental oil production. The main object of development is PK1-3 formation (Pokur suite) which contains considerable oil and gas reserves. PK1-3 formation, deposited in continental sedimentation environment, is characterized by wide variety of facies with diffe rent sand proportion content. It provides high facies differentiation and high uncertainty of extension and position in space of formation sand bodies. At this moment, the field is at the development drilling stage, but new data shows that current geological model has low level of prediction ability. Considering this, the selection and application of such modeling parameters that would allow taking in to account reservoir heterogeneity and raise the predictive ability becomes a critical issue of the project. This study includes analysis of different variations of geological modeling methods and parameters with factoring in their uncertainty, and estimation of the model predictive probability. Furthermore, it contains analysis of all data, which could raise the predictive ability. Multirealisation modeling is performed using most suitable modeling methods, identified according to the results of the complex analysis of initial data and variations of modeling methods. The proportion of sand penetration and the evaluation of its deviation from the fact number serve as parameters for the estimation of predictive ability. Based on the modeling results, a comparison of methods and their predictive ability is performed using different parameters. Moreover, this study suggests the optimal drilling method for fluvial deposition under the low prediction condition.
Проект «Мессояха» является одним из приоритетных проектов компании «Газпром нефть», призванный в ближайшем будущем обеспечить значительный прирост добычи нефти. Рассмотрен ПК1-3 (покурская свита), который вмещает значительные запасы нефти и газа. Отложения пласта имеют континентальный генезис, который характеризуется широким набором фаций с различной долей песка. Это объясняет высокую фациальную изменчивость и значительную степень неопределенности положения и протяженности коллекторов в пространстве пласта ПК1-3. В настоящее время на месторождении ведется активное эксплуатационное бурение, результаты которого свидетельствуют о низкой прогнозной способности текущей модели. Наиболее актуальной задачей становится подбор таких параметров для геологического моделирования, которые позволили бы учесть неоднородность пласта и повысить прогнозную способность. Представлены анализ возможных вариаций построения геологической модели пласта с использованием различных методик с учетом неопределенности входных параметров и оценка их прогнозной способности на примере моделирования сектора. Приведен также анализ всей имеющейся информации, которая позволила бы улучшить прогнозную способность. По результатам комплексного анализа вариаций построения и исходной информации выбраны наиболее подходящие методы моделирования и выполнены многореализационные построения. Проверочным критерием для оценки прогнозной способности являлись доля проходки и ее отклонения от фактического значения. По результатам моделирования выполнено сравнение методов по различным критериям, позволяющим оценить эффективность методов. В дополнение предложен оптимальный способ вскрытия коллектора речного генезиса в условиях низкой прогнозируемости.
Ipatov, A. I. (Gazpromneft LLC Research and Development Centre) | Nemirovitch, G. M. (Messoyahaneftegaz CJSC) | Nikolaev, M. N. (Messoyahaneftegaz CJSC) | Shigapov, I. N. (TGT Oilfield Services) | Aslanyan, A. M. (TGT Oilfield Services) | Aslanyan, I. Y. (TGT Oilfield Services) | Petrova, I. A. (TGT Oilfield Services)
A pilot project comprising several closely-spaced wells from one pad was carried out in the green East Messoyakha field for further study of properties in this field. The target zone in this field is the oil rim of a highly stratified reservoir containing a gas cap and an aquifer. The field is developed with a system of horizontal wells with horizontal sections up to 1000 m long. Development of such reservoirs always calls for monitoring inflow zones and inflowing fluid composition for timely prevention of gas and water ingress into the wellbore resulting from coning or lateral breakthroughs through the highly permeable zones and for assessment of the reservoir depletion. Horizontal wells in this field are completed with uncemented liners and packers, which makes the task of reservoir flow analysis even more complicated due to the complexity of flow geometry behind the liner.
Accordingly, logging techniques that have a sufficiently deep radius of investigation to be able to collect the required information about the reservoir, such as spectral noise logging (SNL) and high-precision temperature logging (HPT) were used for profiling inflows from the reservoir into the horizontal wellbore section. The SNL tool captures noise signals produced by reservoir fluid flows and has a radius of investigation up to several metres. Such noise signals have a distinctive frequency signature and can be therefore extracted from the entire noise spectrum recorded in the well. Identification of flowing zones using SNL technique is based on this principle. To quantify inflows from the formation, a temperature log analysis is performed using TermoSimTM software system that can simulate thermal processes in the wellbore, surrounding rocks and flow units, and estimate inflow rates by solving the inverse problem. As the survey was conducted in closely-spaced wells, numerical simulations were run with the same subset of input parameters (such as initial temperature distribution etc), which greatly improved the inflow profile reliability.
As a result of the derived inflow profiles analysis, the sources of water encroachment and high gas content in oil during well operation were identified. The inflow profile correlation analysis applied to a group of closely-spaced wells helped to understand the general principles of reservoir-to-wellbore flow geometry in specific geological environment. Data interpretation results were used for planning well interventions with the purpose of improving the performance of production well. The resulting inflow profiles might be incorporated into the field hydrodynamic model to enhance its predictive ability.