Horizontal Wells 2021

The deepening of the sensors of the surface locating system under the low-velocity zone compensates for the influence of inaccuracy in the knowledge of the velocity model in the upper part of the section, reduces the level of registered surface noise and expands the upper limit of the operating frequency range. All this increases the sensitivity to weak events and the accuracy of event location in general. The formation of a hydraulic fracture leads to a change in filtration flows in the reservoir in the well area, which in general should affect the change in flow rate not only in the well with hydraulic fracturing, but also in the adjacent wells. Correlation analysis between daily fluid flow rates in wells before and after hydraulic fracturing, in the presence of statistical relationships, allows to establish a change in the direction of fluid movement in the considered element of the development system and to give a qualitative assessment of the fracture azimuth obtained from the results of microseismic monitoring.

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Lateral changes of lithology can reduce the reliability and efficiency of geosteering when using only reference wells. Using 3D seismic data in addition to reference vertical wells can improve the efficiency of horizontal wells planning and geosteering. The oil field considered in this study is covered by 3D seismic survey and 6 exploration wells. The Neocomian terrigenous reservoir is being developed with horizontal wells Seismic-well-tie show that lithology changes within Neocomian reservoir can lead to time shift between stratigraphic well top and seismic reflection. Seismic facies mapping was performed using seismic attributes and verified by horizontal wells data. Result seismic facies map can be used for optimal well placement

Complex of methods, presented in this work, allows to identify active fluid migration zones of natural or technogenic characters. Application of this complex is especially relevant due to existing areas, which underexplored or not explored by seismic methods. The proposed method allows to promptly predict the existence and spatial position of sedimentary cover active fluid migration zones at minimum cost. In such zones, the fluid migration can occur laterally (along faults, blocks boundaries, etc) and vertically. The information, which obtained using this technique, can be applied for planning of horizontal wells and network of injection wells, interpreting hydrodynamic modeling data etc.

The results of comprehensive work that led into an increase in drilling efficiency, an improvement in the starting flow rates of drilled wells, and a decrease in estimated economic losses are reflected.

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Drilling process geological monitoring becomes more critical due to horizontal drilling percentage increase over the last two decades. That results in a growth of LWD operative interpretation demand and makes necessary to provide the formation evaluation data as soon as possible. This paper represents the automation of LWD interpretation process with automatic data import and export via the remote server. Decreasing the process life of operative interpretation we manage to increase the geosteering efficiency. This work examines formation evaluation and calculation of the mineral volumetric fractions. Collector, lithology and formation fluid type are determined by the cut-off values method. Data transmission (both import and export) is performed via the classified remote server WITSML. The represented approach has shown its efficiency on practice. It makes log quality control more effective and optimizes the workflow by cutting down unproductive routine operations.

The report considers the problem of fluid flow to a well with multistage hydraulic fracturing (MSHF) in an infinite and bounded homogeneous isotropic formation. An approximating dependence of the skin factor in a horizontal well with multistage fracturing on its parameters has been obtained. Calculation formulas for expressing the skin factor was derived. Based on the solution of the diffusivity equation for a bounded formation with a boundary condition of the first kind, rates and cumulative production for the well were obtained with good accuracy. An economic estimation of the optimal number of hydraulic fracturing stages was presented. To evaluate this values specialized script is written by means of Python programming language.

The use of new methods for processing seismic data makes it possible to refine the tectonic model of the field, to forecast zones of increased and decreased productivity in the production horizons. This is necessary for a reasonable choice of directions and lengths of horizontal and directional wellbores in the most fractured zones in order to maximize production rates. The fracture zone map serves as the basis for the design of the field development scheme. Initially, it is recommended to lay wells in zones of increased fracturing of the productive horizon, while avoiding or taking into account the zones of possible complications during drilling, which are present in the overlying horizons. If the location of the well pad has already been determined, the resulting map will help to adjust the azimuth and length of the horizontal sections of the wellbores to undercut the zones of increased productivity.

This thesis presents the technology for assessing the risks of mud losses during drilling using 1D geomechanical modeling in conjunction with the seismic interpretation data MOGT-3D. Based on a combination of seismic and geomechanical data, a methodology has been developed for estimating the equivalent circulating density values, above which the mud losses will appear during drilling, which makes it possible to predict drilling risks and provide measures to prevent them without increasing the cost of drilling. In the examples considered, the forecast of mud losses by this method has a 72% confirmation (21 out of 29 wells). In order to further improve the technique, a number of measures have been proposed, including, conducting special methods of geophysical well logging to determine the nature of zones with increased mud loss risks and clarifying the direction of maximum horizontal stress, as well as performing leak-off tests (LOT and XLOT) for estimations of mud loss and hydraulic fracture pressures. The seismic-geomechanical model constructed according to the proposed method can be used to solve other equally important tasks: search for zones of increased reservoir properties, the location of the ports of multistage hydraulic fracturing, risk assessment of increased wear of bits and others.