Abstract

The development of hydraulic fracturing technology began with single operations and is currently the most effective tool for increasing the productivity of wells and managing field development. Without the application of the hydraulic fracturing method, many fields would not have been successfully put into operation. For example, in the USA, hydraulic fracturing technology is used almost everywhere, which enabled an increase in the share of recoverable reserves by 25-30%. The first hydraulic fracturing in our country was carried out in 1952. After this, the number of such works increased for several years, but then declined. This was due to the industrial development of large oil fields in Western Siberia. The application of hydraulic fracturing technology was resumed in the 1980s and has been growing steadily ever since (Usachev, 1986).

Horizontal drilling technologies are currently developing at a fairly rapid pace, which entails an increase in the accuracy of penetrating a given part of the formation. Multi-stage hydraulic fracturing is primarily used in the well to increase the flow rate. It is expected that in the perspective of 2019-2020, the share of horizontal drilling will reach 46-50%, which is due to plans for the intensive development of new fields in Eastern Siberia (Figure 1).
Figure 1

Dynamics of the number of wells completed using horizontal and controlled directional drilling in Russia in 2008–2026 (fact and forecast), units

Figure 1

Dynamics of the number of wells completed using horizontal and controlled directional drilling in Russia in 2008–2026 (fact and forecast), units

There has been a steady increase in the share of horizontal drilling with the total volume of production in Russia since 2008 (Figure 2). This indicates qualitative changes in the technological approaches of today's production companies.
Figure 2

Dynamics of throughput volume in production drilling in Russia in 2008–2026 (fact and forecast), mln. m.

Figure 2

Dynamics of throughput volume in production drilling in Russia in 2008–2026 (fact and forecast), mln. m.

Technical solutions are required for the delivery of geophysical equipment to the horizontal section of the well for horizontal wells production logging using an electric centrifugal pump (ESP). The existing Y-tool technology allows for lowering the geophysical equipment to the coiled tubing system, therefore bypassing the ESP system in close proximity to well operation mode, but this increases the well completion cost by 25%.

Along with the conventional methods of horizontal wells production logging such as PLT logging, oil producing companies are increasingly beginning to apply innovative methods based on marker technology. This method applies the flow indicators that are able to trace the flow of each phase into the well separately and continuously for several years. The objective of this article is to describe the results of using the fluorescent microsphere method, taking into account their long-term use for estimating the inflow structure from each port of hydraulic fracturing in horizontal wells. This helps users to avoid risky and costly downhole operations at the pilot development stage.

Markers are monodisperse polymer spheres containing their unique code for each hydraulic fracturing stage. In the presence of a stream of water or oil over the surface of the proppant, only markers corresponding to their phase are released. Upon completion of all the works in the well, it is put in the planned mode of operation. After this, sampling of the formation fluid from the wellhead is performed. A specialized laboratory analyzes the samples to determine the concentration of markers for each code.

Production logging of the well with the application of marked proppant is carried out continuously for several years. The inflow profiles of the formation fluid along the horizontal well were designed on the basis of data obtained by analytical comparison. Long-term production logging will allow for a long-term analysis of the effectiveness of stimulation for each of the hydraulic fracturing stages and will aid in assessing the reservoir section's reserves.

One of the main advantages of this technology compared to traditional methods is the ability to obtain data on the intervals operation without requiring special means of instrument delivery. As a result, the technology minimizes the risk of downhole equipment getting stuck and is not subject to ambiguity in data interpretation. The technology of marker production logging has received confirmation throughout the market based on its performance. The placement of inflow indicators was carried out in the hydraulic fractures, thereby ensuring the long-term selective interaction of marker particles with the water and oil phases of the formation fluid. Information on the inflow profile obtained as a result of the analysis allows for planning effective geological and technical measures and leads to an increase in the hydrocarbon extraction coefficient.

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