The paper presents the results of a comparative analysis of strength envelopes plotted by two methods — in accordance with GOST 21153.8 and by the multi-stage loading method (
Kazakov, E. (Schlumberger) | Vereschagin, S. (Schlumberger) | Kichigin, A. (Schlumberger) | Olennikova, O. (Schlumberger) | Ishangaliev, A. (Schlumberger) | Bulatov, F. F. (GAZPROMNEFT-YAMAL) | Saifutdinov, E. (GAZPROMNEFT-NTC)
Today, an effective application of multistage fracturing (MSF) became an acute problem for the Yamal Peninsula fields. At Novoportovskoe oil and gas condensate field, in order to achieve an effective reservoir coverage with fractures to increase hydrocarbons recovery, it was decided to revise the concept of horizontal wells completion, increasing the number of MSF stages and decreasing the distance between the stages.
In the complex geological conditions of the Novoportovskoye field, a fundamentally new solution was proposed for horizontal well completion – full bore MSF system with sliding sleeves, operated by hydraulic shifting key with coiled tubing (CT). This completion system allows to perform MSF without pulling CT out of the well to the surface and instantly use CT for well clenout in the case of screenout (SO). This decision is aimed to increas production and achive economic efficiency of the field development by increasing the formation coverage by means of larger number of MSF stages per well, and optimizing costs by reducing the time for the entire range of work at the well.
At the moment, 2 wells at Novoportovskoe field were completed with described MSF system, with total 40 stages fractured.
The technology allowed increasing of stages number to 20 in a 1000 m long horizontal section and installing selectively ports in the most effective zones of the formation. The coefficient of formation coverage was increased due to uniform placement of longitudinal fractures, which could not be achieved with standard "ball" MSF technologies.
As a result, by reducing treatment size and increasing number of stages, positive results were achieved: the water cut was 39%, with an average of 60% and the gas factor was 472 m3 / tonne, with an average of 800-1000 m3 / tonne in neighboring wells.
As a result, with use of integrated completion system with shifting ports, fracture control was obtained in real time due to coiled tubing functioning as a dead string during fracture, and, at the same time, data was stored at memory downhole gauges installed in the CT bottomhole assembly (BHA).
Innovative technology and a comprehensive approach to the design and implementation of fracturing operations in complex geological conditions of the Novoportovskoe field is a unique experience for the region. The possibility to increase an oil production of a horizontal well MSF (HWMSF) without breaking fractures into the gas cap was proved. This system has advantages with respect to standard MSF technologies in conditions of oil rim deposits, and is applicable for other projects where an increase of MSF stages and the completion cycle time reduction is required.
In this paper, key aspects of constructing a hydrodynamic model of high-pressure air injection into Bazhenov source rocks were highlighted. Most of them are associated with the choice of pseudo-components of kerogen required to describe thermal decomposition and oxidation of kerogen and needed for construction of a kinetic model. Sensitivity analysis was carried out. As a result, high sensitivity of output to the change in the content of components reflecting the presence of kerogen in the formation and its participation in oxidation processes and thermal decomposition was confirmed.
Based on the above, a list of experimental studies was formulated, which must be carried out to determine the parameters of numerical simulation and to evaluate the effectiveness of the high-pressure air injection method.
High-pressure ramped temperature oxidation of kerogen was carried out. As a result, temperature profiles, gas composition, and volume of generated/displaced fluids were obtained. 24.8 g of water-oil emulsion were generated from 92 cm3 of rock. Kerogen in the sample was completely converted, which was confirmed by the results of conducted pyrolysis studies.
Ipatov, A I (LLC Gazpromneft STC) | Kaeshkov, I S (LLC Gazpromneft STC) | Krementskiy, M I (LLC Gazpromneft STC) | Bazhenov, D U (LLC Gazpromneft-Jamal) | Buyanov, A V (Gubkin Russian State University of Oil and Gas) | Panarina, E P (Gubkin Russian State University of Oil and Gas) | Figura, E V (CJSC Laser Solutions) | Klishin, I A (LLC Gazpromneft NNGGF) | Nukhaev, M T (Siberian Federal University)
The PDF file of this paper is in Russian.
This paper presents the results of long-term monitoring based on distributed fiber-optic sensing in producing horizontal well. The reported data illustrates high informative value of non-stationary temperature logging used to control well operation, inflow profiling and formation depletion.
Chirgun, A. (Verkhnechonskneftegaz) | Levanov, A. (Tyumen Petroleum Research Center) | Gordeev, Y. (Rosneft Oil Company) | Lazeev, A. (Rosneft Oil Company) | Timchuk, A. (Western Siberia Scientific and Research Institute of Geology and Geophysics)
The PDF file of this paper is in Russian.
A number of large greenfields has lately been brought into development in Eastern Siberia, Russia, one of which being the Verkhnechonskoye oil and gas condensate field. There, for the first time in the history of domestic oil and gas production at regional scale, geologists faced a high-mineralized section, where the pore space of productive horizons is partially or fully filled with salt, which defines differential characteristics when developing new assets.
This study highlights the field development in the context of uncertainties, and the risk control strategy. It describes solutions for well operation in low temperature formations and for maintaining the oil-rate plateau using new approaches to development of sections of low formation reservoir properties (FRP) and under-gas-cap zones with the contact reserves of oil.
The work objective of research is improving the quality of the reservoir modeling of the shelf deposits in the Neocomian clinoform complex by means of identification the peculiarities of geologic structure of the layers, and using of them for create the geological models oil and gas reservoirs. The subject of research is BU16-18 layers in East-Urengoy and North-Esetinsk field. The main peculiarities of BU layers are lenticular body, the vertical and the lateral anisotropy of reservoir properties in the reservoir volume, the presence of transition water-oil zone in consequence of layer`s heterogeneous.
For identification and reservoir modeling of the peculiarities of geologic structure the shelf`s genesis layers used the results of seismic attribute analysis, fractional and mineral analysis of the rocks, conceptional model analysis about accumulation shelf sediments.
The result of the research are detecting all the peculiarities of geologic structure the shelf`s genesis layers such as lenticular body, the anisotropy of reservoir properties, the presence of transition water-oil zone. All peculiarities was introduced for create the geological models: structural framework building, expansion of the reservoir properties in the interwell space, saturation modeling taking into account transition water-oil zone parameters.
Several facets and uncretainties are present in petroleum oilfield operations, due to which decision making is a crucial process that ensures operational viability. For the purpose of decreasing risk and providing better insight, uncertainties must be reduced through a well-organized historical database. This is critical especially in the development of new fields.
An understanding of the cause-effect relationship between attributes and outcome of field operations can be gained through statistics. Through the use of statistical methods there is an opportunity to turn large amounts of data into knowledge for efficient decision making. Unfortunately, the lack of a well organized historical database limits the use of these data for improved results.
Reservoirs, being physically complex systems or having comple relations between the causes (attributes) and effects (outcomes), could use a multi-attribute based statistical model that will allow for improved results of future actions through better decision making. The first step in building a data driven model collection of relevant historical data pertaining to the phenomena to be modelled. Significance of each attribute of the historical data to the outcome is mapped through a multi-variate regression. From this analysis optimum range for each attribute that will give best results and maximize returns can be identified. It must be noted that relevant attributes must be those events and key parameters that largely influence the outcome.
In this study, performance of vertical and horizontal wells in tight reservoirs was selected as the outcome with the factors affecting it to be modeled. A numerical simulation model has been used for validating the data-driven model by determining the significance of each parameter and the optimum operating intervals.
The PDF file of this paper is in Russian.
Geological objectives during horizontal well drilling operations are increasingly challenging. The objective during geosteering in uncertain conditions is the determination of the oil/water contact (OWC). Understanding the OWC position is crucial to oilfield production. Typically, the OWC position is determined by evaluating exploration wells. However, there is uncertainty in how it is transposed across a field when faulting is evident or water injection operations are in place. There is additional uncertainty regarding the well position because various corrections can be made to the directional measurements from the survey tools. Therefore, when geologists are faced with the task of holding a well a certain distance from the OWC, it is not always correct to fully rely on inclinometer measurements. The absolute mark can be any mark with a certain probability within the ellipse of uncertainty. This paper presents an example of how a trajectory based on static measurements with a discreteness of 10 m could differ from a trajectory constructed from a dynamic survey with a much smaller sampling rate. The method proposed uses an azimuthal deep resistivity tool to identify and quantify the distance to the OWC.
Karachaganak is a giant gas-condensate field located in north-western Kazakhstan. In 1997 a production sharing agreement was signed between the partner companies and the Republic of Kazakhstan. Karachaganak Petroleum Operating b.v. (KPO b.v.) joint venture is operated by Shell (previously BG-Group) and Eni S.p.A. Chevron, LUKoil and KazMunayGas are the rest shareholders in this project. Karachaganak was discovered in 1979 and the production began in 1984.
The field comprises Permian and Carboniferous reservoirs with complex geological and fluid properties. The reservoir fluids are gas-condensate with the underlying oil leg.
Since 1997 the focus of the field development has been on the oil leg with the objective of producing low gas-oil ratio (GOR) oil. This is being achieved by drilling sub-horizontal wells. The design of these wells is aimed at maximising the reservoir contact to overcome the challenges of significant heterogeneity present in the field. It also allows accessing partially or fully isolated compartments associated both with reservoir heterogeneity and with the presence of clinoforms formed during the prograding phase of the Carboniferous platform evolution. Initially a drain length of sub-horizontal wells was limited to 700 metres by the available drilling technology. Today, modern rigs are capable of drilling a single 2000 metre long sub-horizontal drain to a total well length of more than 6600 metres. Simulation studies indicate that long drains optimise the field development by reducing the number of wells required to maximise the oil recovery. This paper focuses on the impact that drilling long sub-horizontal wells has had on well performance in the Karachaganak field. The paper also discusses the evolution of the well completions from open-hole drains to multistage stimulation completions that allow selective stimulation of a drain interval.
The PDF file of this paper is in Russian.
In this paper, the effect of local changes in the stress-strain state of rocks is analyzed, and an appropriate approach is proposed for modeling the geometry of hydraulic fractures on horizontal wells under conditions of a dense drilling network, including Zipper Frac technology. The main source of factual information on the development of cracks are the pressure curves obtained during injection tests, mini-fracs and main frac jobs, including fracs on offset wells and microseismic monitoring of fracturing.
At Vinogradov field as the optimal selected row production system. The analysis of the accumulated experience made it possible to identify promising areas for increasing the efficiency of the production system, including reduction in the distance between rows, a change in well azimuths relative to the principal stresses, and the extension of horizontal sections of the wells.
In this paper, we analyze the results of multi stage HF in conjunction with modeling the geometry of cracks in various software products, taking into account and without taking into account the local change in the stress-strain state of the rocks near hydraulic fractures. The simulation results are cross-validated with actual information on the various wells of the development object under consideration.
Modeling and analysis of the geometry of cracks in neighboring wells, oriented both longitudinally and transversely with respect to the direction of maximum horizontal stress, is carried out. Including the mutual influence of stages of Zipper Frac technology is analyzed.
Taking into account the effect of local stress redistribution made it possible to achieve a high degree of correspondence between the results of modeling available actual information from the target wells and the environment wells (pressure responses, microseismic results and production figures). Without taking this effect into account, it was not possible to achieve such a degree of compliance.
The conclusion is made that the effect of local stress redistribution both during fracturing at adjacent ports of a single horizontal well and fracturing of adjacent horizontal wells has significant influence on geometry and, in particular, to the fracture height, which is critical in the geological conditions of the considered object.
An approach to modeling and planning of the multi stage frac on horizontal wells in conditions of complex reservoirs similar to the object under consideration was developed. In particular, new approaches to the optimization of the sequence of Zipper Frac stages are proposed and recommendations are made for carrying out fracturing in the conditions of both longitudinal and transverse drilling mesh in relation to the direction of the maximum horizontal stress.