Serikkali Amangaliyevich Brekeshev - Deputy Chairman of the Management Board of NC KazMunayGas JSC

Anton G. Bachurin – Head of the Department of Energy Efficiency and Renewable Energy of NC KazMunayGas JSC 

What are the geological features of the Caspian, Ustyurt-Buzachinsky and Mangyshlak basins associated with the history of their sedimentation? What are the results of analysis of suitable fields for CO2 injection and the results of the search for suitable potential traps for CO2 burying? Where the boundaries of the pilot project of NC "KazMunayGas" JSC will lie ? The authors of the article reflect on all this, as well as on the concept corresponding to the three scenarios, and on the legislative barriers preventing the implementation of projects.

Analyzing its business processes within the framework of implementation of Low-Carbon Development Program for 2022-2031, as well as taking into account the development of the Kazakh economy, JSC NC KazMunayGas concluded that it is impossible to achieve carbon neutrality without the use of carbon capture, utilization and storage systems (CCUS).

In this regard, the Department of Low-Carbon Development of JSC NC KazMunaiGas, with the expert support of KMG Engineering LLP, has started implementing a pilot project on CO₂ capture, utilization and storage (CCUS) and determining the potential for CO₂ injection in order to increase oil recovery of depleted oil reservoirs (see Figure 1). At the moment, the project is at the stage of a preliminary feasibility study, within the framework of which CO₂ sources are being screened, geological surveys are being carried out at the fields of JSC NC KazMunayGas and a search is being carried out for possible traps for CO₂ burying in the immediate vicinity of CO₂ emission sources under the management of JSC NC KazMunayGas.

We started our research with an express analysis of the history of sedimentation from the point of view of the formation of regional reservoirs of the three largest oil and gas basins on the territory of the Republic of Kazakhstan and the spread of potential seals.

Devonian rifting of the Southeastern European Platform contributed to the formation of the Caspian basin with massive carbonate uplifts along the flanks. The immersion of the basin in the carboniferous age led to the subsidence of the basin, where the formation of carbonate structures continued with minimal introduction of terrigenous rocks.

The Late Paleozoic collision of the European and Kazakh tectonic plates limited the Caspian basin from the ancient Tethys Ocean, which led to the formation of a powerful salt layer in the Kungur age and to extensive deformation of the areas of Northern Ustyurt and Mangyshlak.

The erosion of the impending Kazakh plate entailed the introduction of alluvial and fluvial terrigenous sediments into the northern part of the current territory of the Caspian Sea.

The ongoing salt tectonics has created complex geological suprasalt structures in the Caspian basin.

Collisions of different microcontinents led to inversions, formations of folds and erosion of rift basins of Triassic age in the Northern Ustyurt and the Central part of the Mangyshlak basin

The uplift of the Ural Mountains in the early and Middle Jurassic led to the subsidence of the Ustyurt-Buzachinsky and Mangyshlak basins and the accumulation of fluvial, lake and shallow facies in the region. Therefore, sedimentation of marine carbonates prevailed in the Upper Jurassic. At the same time, the accumulation of marine terrigenous sediments continued until the Middle Cretaceous age, followed by the accumulation of marine carbonates.

The Caspian basin has limited properties for storing CO₂ for a number of reasons. At the same time, the subsalt part of the Caspian basin lies at great depths, where high pressures and temperatures prevail, and the above-salt floor has a complex geological structure and uneven distribution of reservoirs due to active salt tectonics, which affected the significant anisotropy of the existing reservoirs. At the same time, the recent sediments of the Caspian basin are located at depths unsuitable for CO₂ storage.

Taking into account the history of sedimentation, our team came to the conclusion that the most likely prospects in terms of CO₂ storage are terrigenous fields of the Lower and Middle Cretaceous of the Mangyshlak sedimentation basin and, to a limited extent, the western part of the Ustyurt-Buzachinskiy basin. At the same time, Late Cretaceous marls and local intraformational clays serve as a regional seals.

The Caspian basin has a number of restrictions that significantly limit the possibility of dumping CO₂ emissions.

Despite the limitations of the Caspian basin, our team scrupulously performed screening of all active sources of CO₂ emissions in all three basins and determined their type, volume, and location. In addition, based on the project documentation, we also took into account all the promising sources of emissions that should appear in this region in the next five years.

After that, in order to select a suitable field for CO₂ injection and search for suitable potential traps, we continued a detailed analysis of the geological structure within a radius of 100 km from these sources of CO₂ emissions.

Preliminary selection of fields for CO₂ injection to increase oil recovery was carried out by screening analysis of 21 fields.

At the same time , the main criteria for the selection of fields were:

- sufficiency of emissions from the main nearest source;

- depth of occurrence - more than 700m;

- sufficient volume of the operational wells stock;

- geological oil reserves.

According to the main criteria, 6 fields were selected - Kalamkas, Zhetybai, Uzen, Karamandybas, Asar, Vostochny Zhetybai.

The database for these fields was formed for 63 operational development facilities for further analysis using additional evaluation criteria, such as: depth, viscosity and density of oil, as well as the absence of a block structure and a gas cap at the fields.

At the same time, it is important to understand that the main criterion for the effectiveness of CO₂ injection into the reservoir is the condition of miscibility of carbon dioxide with oil, provided by reservoir pressure, therefore, the values of the minimum miscibility pressure were calculated for all development facilities using correlations.

As a result, the Karazhanbas and Kalamkas fields were excluded due to the high viscosity of reservoir oil, and the Asar field was excluded due to the lack of representative downhole samples.

At the same time, a detailed analysis of the geological structure within a radius of 100 km from the sources of CO₂ emissions located in the southeastern part of the Caspian Basin confirmed our preliminary conclusions, which were mentioned earlier (see Figure 3). In particular, only four potential traps were identified, while only one trap with a very limited injection volume was identified in relative proximity to KPI and KLPE.

As for the detailed analysis of geological structure of the Caspian Basin, despite the fact that the deposits of the Prorvinsk group were excluded at the stage of the screening analysis of the field, we identified 15 large traps that are potential storage for CO₂ (see Figure 4). At the same time, the absence of large concentrated sources of emissions in the immediate vicinity of these traps makes these traps unpromising from the point of view of the CCUS project.

Detailed analysis of the geological structure of the Ustyurt-Buzachinsky basin identified seven potential traps, while the Karazhanbas and Kalamkas fields themselves were unacceptable for CO₂ injection due to the high viscosity of reservoir oil (see Figure 5).

Detailed analysis of the geological structure in the Mangyshlak sedimentation basin, as expected by the results of the preliminary assessment, showed the most interesting results (see Figure 6).

First, large potential traps suitable for CO₂ disposal have been identified. Secondly, the Uzen and Zhetybai, Vostochny Zhetybai and Karamandybas field located in the Mangyshlak sedimentation basin turned out to be acceptable for CO₂ injection into them. They are located in close proximity to large potential sources of CO₂ emissions, the construction of which is planned in the medium term (the new KazGPP and the OMG gas power plant). The design CO₂ emissions of OMG and KazGPP combined total more than 400 thousand tons of CO₂

Taking into account all the above, it is in this region that JSC NC KazMunayGas decided to concentrate its further efforts in developing the concept of a pilot project focused on increasing oil recovery of the Zhetybai and Karamandybas fields.

Based on several scenarios, our team is developing a conceptual design (composition and location of the main equipment) of the ground infrastructure.

At the same time, in order to generate a positive cash flow of the project for Zhetybai, Karamandybas and Uzen fields, work is being completed on the calculation of profiles for KIN, taking into account the level of oil miscibility and reservoir capacity, for the following horizons:

- four horizons of the Zhetybai field;

- two horizons of the Vostochny Zhetybai field;

- and one horizon at the Uzen and Karamandybas fields.

Unfortunately, despite the proximity of the Uzen field to the sources of CO₂ emissions, we were forced to abandon the idea of using it due to the insufficient level of oil miscibility. That is why the final scenarios for the development of ground infrastructure did not consider the option of injecting CO₂ into the Uzen field.

The project team is adapting additional production schedules for the two most acceptable fields Zhetybai and Karamandybas.

After completion of this stage of work and assessment of capital expenditures for the development of ground infrastructure, JSC NC KazMunayGas will be able to model financially the project (approximately the III quarter of 2023). After development of the financial model, JSC NC KazMunayGas plans to finally approve the concept of the pilot project and consider the possibility of implementing a pilot project for STC of SK Fund with subsequent inclusion in the list of R&D projects of the SK Fund.

In case of a positive decision, JSC NC KazMunayGas plans to carry out the next stage of detailed modeling and design at the expense of R&D of SK Fund with the involvement of international companies specializing in these works.

At the same time, it is worth noting that the capture, utilization and storage of CO2 is currently an innovative technology and there is no experience in implementing such projects in Kazakhstan, so our team of experts is expected to face significant gaps in the legislation of the Republic of Kazakhstan.

First of all, these are, of course, issues of subsurface use. In particular, according to subparagraph 2) paragraph 3 of Article 213 of the Environmental Code of the Republic of Kazakhstan, the injection of technological solutions and (or) working agents into the subsoil for mining in accordance with the projects and technological regulations for which environmental permits and positive expert opinions provided for by the laws of the Republic of Kazakhstan have been issued is not a discharge of pollutants. At the same time, there are no regulations on CO₂ injection in Kazakhstan at the moment.

In addition, with the almost complete absence of technical regulations and standards, there is no possibility of design, and the implementation of a pilot project becomes simply impossible.

JSC NC KazMunayGas is currently considering the possibility of attracting experts in international and local law in order to:

- study the successful international experience of legislative and technical regulation;

- identify existing gaps in the legislation and technical regulation of Kazakhstan;

- develop a set of legislative initiatives and a list of technical standards and regulations aimed at the implementating CCUS projects in Kazakhstan.

JSC NC KazMunayGas hopes that within the framework of this work we will be able to establish a direct dialogue of the experts involved with the authorized bodies, which will ensure the effectiveness of joint work to eliminate legislative gaps.