Том 4, № 2 (2022)

Neural networks and machine learning have long been used by almost everyone in their daily lives, perhaps not always consciously. When an algorithm of social networks identifies the faces of people in a photo or a voice assistant helps us search for some information, machine learning techniques underpin all of these activities.

In recent years neural networks are finding more and more applications in the fields of oil and gas exploration and production. This article aims to illustrate an example of the application of neural networks in the analysis of seismic data for an active oilfield by predicting 3D cube of petrophysical properties to further detail the geological model and search for additional hydrocarbon accumulations.

One of the key conditions for successful prediction of petrophysical properties using neural networks is a wide sample of well data for effective training of a non-linear operator. In our case, since it is a producing field, there were more than 100 wells available, which fully meets the requirements of the algorithm. Another important condition for application of this technique is having high-quality well ties for the used wells, this step of the workflow will also be described within the article.

A distinct feature of neural network analysis, in contrast to classical inversion, is that it does not use a seismic wavelet. The neural network automatically determines such an operator that best describes the correlation between several seismic traces in the wellbore area and the log curve. This feature reduces the analysis time and produces express results if the above mentioned conditions are met, which makes the neural network technique an effective tool for dynamic analysis of seismic data.

Horizontal drilling is currently being actively developed in the near and far abroad to increase oil production, and Embamunaigas JSC is a prime example of this type of drilling in Kazakhstan. At the same time, horizontal drilling is a fairly complex and costly process, just like the construction of deep exploration wells, which requires a comprehensive approach to planning and execution of work.

Geomechanical modelling plays a crucial role in selecting process parameters for drilling, determining optimum well design and other characteristics required to ensure wellbore integrity and overall well construction success.

The mechanical properties model takes into account rock strength characteristics, horizontal stress directions of the geological environment and many other aspects that help make drilling safer, reduce the risk of complications and maintain borehole integrity.

This study describes the process of creating geomechanical models for the construction of complex horizontal wells in the fields of Embamunaigas JSC based on the geomechanical core studies carried out at the S. Nurzhanov field and an analysis of the hydraulic fracturing database for the fields of Embamunaigas JSC. As a result, a safe drilling mud density range (“safe drilling window”) was determined and recommendations were given for the optimisation of drilling parameters and well design.

Thermal enhanced oil recovery methods are a traditional approach in the primary and secondary development of heavy oil fields. Despite the effectiveness of such methods, there are breakthroughs of working fluid into production wells due to the presence of high permeability channels, resulting in a sharp increase in the watercut and an increase in the bottom hole temperature.

The article presents a literature review of the world experience in application of various steam conformance control methods. Based on the literature review, the applicability of foam systems at the Karazhanbas field was studied; core flood experiments were carried out to determine resistance factor and displacement efficiency. Obtained results confirm the formation of foam in reservoir conditions by increase in injection resistance during its filtration through core sample and visually at the outlet, the increase in displacement efficiency was 17,41%. The scientific novelty of the work lies in the study of the applicability of steam conformance control technology based on foam, which has not been previously studied and tested at any field in Kazakhstan.

The article comprises of the results of research work on a solution for injecting water into a gas cap in the field located on the shelf of the Caspian Sea. A practically significant approach has been identified, a concept was developed, as well as the necessary conditions for pumping water into the gas cap. An analysis of the impact of water injection into the gas cap on the wells of ringing was carried out. The water injection efficiency monitoring program has been developed.

Methods of enhanced oil recovery in general and surfactant-polymer flooding in particular are considered as tertiary methods for the development of mature oil fields in Western Siberia, with the potential to increase oil recovery to 60-70% of the initial geological reserves.

To select an effective mixture of surfactants and polymer for surfactant–polymer flooding, laboratory tests were carried out in which the thermal stability, phase behaviour, interfacial tension and rheology of the formulations were tested. Filtration experiments were also carried out to optimize the volumes of injected fringes and the concentrations of reagents in them. At the final stage, single well chemical tracer tests (SWCTT) were carried out to assess the effectiveness of surfactant-polymer flooding on two wells of the Kholmogorskoye field. In order to investigate different technical and economic models of surfactant-polymer exposure, SWCTT tests were conducted with the same surfactant, but with a different design. The results of the SWCTT tests showed that the residual oil saturation in the affected area after injection of the surfactant-polymer solution decreased by about 11% compared to water flooding, which is about a third of the residual oil after flooding. The tested surfactant showed acceptable efficiency under suboptimal temperature conditions, which is favorable for the use of the selected surfactant-polymer composition for neighboring deposits and formations with different reservoir temperatures, but similar water composition.

In general, the results of the conducted field tests correlate with the results of the main laboratory experiments for the selected surfactant.