Salym Petroleum Development (SPD), a joint venture between Gazprom Neft and Shell, started up the ASP mixing plant – an innovative technology capable of substantially enhance oil recovery at Western Siberia’s mature oilfields. The pilot project on SPD’s West Salym oilfield will provide the required information and set the stage for further large-scale implementation of the technology in Russia.

The majority of oilfields in Western Siberia, which account for nearly half of Russia’s total oil production volume, demonstrate a high level of maturity. According to Subsoil Usage Department of Siberian Federal District, the case in hand is a decrease of production by about 50% in 2013-2015 – from 975 thousand tons to 661 thousand tons. Meanwhile, residual reserves of the fields on which conventional production methods were used are enormous. After application of waterflooding, a conventional formation stimulation method, 60-70% of oil remains in the subsoil, of which 40-50% are arrested in pores and 20-30% in lower permeability zones and traps. Extraction of at least part of this residue is only possible with the help of modern efficient enhanced oil recovery (EOR) methods.

Salym Petroleum Development (SPD), a joint venture between Shell and Gazprom Neft established in 1996 for development of the Salym group of oilfields in Western Siberia, is involved in implementation of one of them – ASP (alkali – surfactant – polymer) technology. SPD reached the peak level of production (8.4 million tons a year) in 2011. Now, taking into account gradual decrease of the volumes, these fields have become an ideal site for testing and application of new enhanced oil recovery technologies.

A promising EOR method
First EOR methods started to appear as early as in 1960s. The majority of these technologies can be divided into three categories: thermal, chemical, and gas. Thermal methods include introduction of steam into formation, the thermal energy reducing oil viscosity and facilitating its movement to a producer. In case of gas methods gas (natural, nitrogen, or CO2) is injected into formation, thus helping to displace oil. Chemical EOR methods assume injection of water solution of chemicals into formation. The most common is polymer flooding which employs a solution of polymers with high molecular weight. The efficiency of application of various methods depends on specific features of each particular field.

ASP technology is a chemical flooding method employing a three-component mixture of alkali, surfactant, and polymer. It was developed in early 1980s in Shell’s U.S. R&D centre. At that time numerous experiments were carried out for joint application of surfactant and polymer to enhance efficiency of their usage. Surfactant reduces oil-water interfacial tension, which makes it possible to mobilize oil arrested between flakes of rock. Polymer increases viscosity of the solution, which enhances efficiency of displacement process for the oil mobilized by surfactant. As to alkali, it reduces wettability of rock with oil, increasing its mobility, reduces surfactant sedimentation on rock, and also produces an additional volume of surfactant in case of reaction with sour oil.

Taking into account the very nature of chemical EOR methods, it is extremely important that ASP technology makes it possible to substantially reduce environmental stress – in particular, due to the fact that in order to implement it no construction of new oilfield infrastructure is required, which notably reduces the volume of waste per ton of additionally produced oil. The chemicals actually injected into formation are used in household chemistry (alkali and surfactant) and in water treatment (polymer).

Another upside of ASP is energy efficiency. Using waterflooding, a conventional EOR method, it would require decades to recover the oil. Meanwhile, with the use of ASP, average oil production time is 3-5 years. However, notwithstanding all the advantages, it has never become the case of large-scale application of ASP technology in the 1980s: it was too expensive at that moment. It was only in early 2000s that Western companies recalled it. The impulse for that was both in the growing need for oil recovery enhancement and in several favourable factors: high oil prices, lower surfactant and polymer prices, as well as appearance of tools for modelling the development involving chemical flooding. At the moment the global perimeter of ASP application is about 20 projects. The greatest success in this area was achieved in Canada, USA, and China.

Russia’s first
Russia’s first ASP technology implementation project is executed at SPD’s West Salym oilfield. Various EOR methods were considered for this asset; however, the research has shown that ASP is the optimal option. Oil viscosity here is low, which makes application of thermal methods unfeasible. Injection of nitrogen, CO2, or flue gases would not yield any substantial incremental production either, since at the formation pressure it is impossible to achieve the conditions required for mixing gas with oil, while gas injection under immiscible conditions is inefficient. At the formation conditions, hydrocarbon gas mixes with oil; however, this method is not promising at the West Salym field either due to shortage of associated gas, while almost all of the APG available is successfully sold. Injection of low salinity water and purely polymer flooding at the late stage of field development would not yield such effect either.

SPD started working with ASP technology in 2008. It is impossible to simply replicate the method form one asset to another: from the point of view of ASP flooding application, each reservoir, each field is unique. Therefore, laboratory tests were to select a recipe of chemicals which would clearly correspond to the composition of formation water and rock mineralogy. To this end, chemico-physical stability of surfactant was first tested at the conditions corresponding to formation. Then they were tested for oil displacement capability on core samples taken from the field’s wells. Field tests carried out on a well in 2009 have confirmed the theoretical calculations: ASP flooding makes it possible to extract 90% of residual oil.

A pilot project is currently executed at the West Salym oilfield, which is intended to reduce technical and economic risks for further commercial application of ASP. In the course thereof it is planned to gather information about efficiency of the new method, acquire an actual experience of operating the specialized equipment, preparing chemical solutions, solve logistics tasks, as well as establish partnership relations with equipment and chemical manufacturers.

"Implementation of the ASP technology at the Salym group of oilfields is a unique experiment for Russia, which opens a new page in the history of oil production in Western Siberia. Ours is the country’s first company to implement an EOR method which makes it technically possible to produce an additional 30% of oil from the subsoil. I am sure that, in case technical risks are removed and required tax incentives granted, this technology will make it possible to develop dozens of fields in Western Siberia in a more rational manner". Alexey Govzich, CEO, Salym Petroleum Development

Within the scope of the pilot seven wells, ASP mixing plant, emulsion breaking module for fluid, and a pipeline have already been built. Capacity of the chemical mixing plant launched by SPD on 24 March this year is 1,000 m3/day. Water treatment and heating, actual preparation of working solutions, mixing, and pumping into injectors takes place on the site.

As evaluated by specialists of V.I.Shpilman research and analytical Centre for the rational use of the subsoil, full-scale application of the new technology within 15 years will make it possible for the company to produce up to 25 million tons of oil additionally. This corresponds to oil recovery factor (ORF)* gain by 10% across the field; as to the flooding spots and sections where the ASP technology is to be applied, ORF will increase by 15-20%. Implementation of the method across the territory of the Khanty-Mansiysk Autonomous Okrug will increase production volumes over the same period by 2.4 billion tons of oil.

In perspective
An outlook like that seems to remove all issues related to future application of modern enhanced oil recovery technologies; however, there is a 'but': they are quite costly. Implementation and dissemination of advanced EOR methods is hindered by economic risks: long payback period and high production cost are the factors aggravated by low global oil prices. In SPD unit oil production cost with application of ASP is estimated today at 5-9 thousand RUR/t. Given the existing tax mode, expenditures like these are difficult to repay; therefore, the lifetime outlook of this EOR method in Russia will depend not only on results of the pilot project but also on the opportunity to establish a privileged tax regime for ASP oil and localize production of chemical components for the technology within Russia. Looking into the history of the global industry it is easy to note that the wide application of enhanced oil recovery methods in the USA has become a result of many years’ support of this work on the part of the authorities. Similar oilfield testing and development programs for modern EOR methods exist in other countries as well: in Canada, Norway, China, Indonesia. 10-15 years later the effort used must yield tangible results. As estimated by International Energy Agency, whilst today about 4% of the global oil volume (nearly 450 thousand tons a day) are produced on account of enhanced oil recovery methods, this figure can grow to approximately 20% (nearly 3.5 million tons a day) by 2030. Thus, the incentives will eventually turn out to grow budget revenue and enhance subsoil usage efficiency.

The need for chemical production arrangements within Russia is also a compelling need. Surfactants such as those used in SPD’s pilot project are not manufactured domestically at the moment – they are purchased abroad, and it doesn’t come cheap. SPD specialists carry out active research aimed at development of the solutions which will make it possible to easily set up manufacturing of surfactants equivalent to those from abroad as well as to find chemically different substances with similar functional features components of which are already being manufactured in Russia.

Neither does Russia have polymers completely equivalent to the chemicals applied in ASP; however, an overall increase in polymer production is currently observed in the country, joint ventures with leading Russian and overseas chemical companies are being established; therefore, by the time ASP is implemented full-scale the demand for polymers can be completely satisfied by domestic vendors. In the aggregate, transition to chemical products manufactured in Russia will make it possible to reduce operating expenses by a minimum of 20-30% exclusive of logistic expenditures reduction.

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