№ 7 (July 2008)
Innovations Open Up the Road to the Future
Today there is an urgent need for innovations in technologies for oil and gas production in abnormal operating conditions...
Today there is an urgent need for innovations in technologies for oil and gas production in abnormal operating conditions. Over 160,000 wells are currently used in Russia for oil and gas production, 70 percent of which have abnormal operating conditions.
Distribution of various hydrocarbons in the total balance of production in 2000 was as follows: light crude amounted to 38 percent, gas – 54 percent, heavy crude – 7 percent, and bitumen – 1 percent. By 2020, the production structure will change in the following way: light crude will be only 25 percent, gas – 47 percent, the share of heavy crude will increase to 15 percent, bitumen – to 10 percent, and gas-hydrate will appear in the production distribution at 3 percent. According to present-day estimates, world reserves of bitumen exceed oil reserves four to five times. 450 fields of natural bitumen have been discovered in Tatarstan, with average occurrence depth varying from 70 to 200 meters; their resources vary from 1.5 to 7 billion tons. The cost of shale oil production is estimated from $110 to $150 per ton depending on the occurrence depth and reserve concentration. An important factor is that starting from 2007 a zero rate of the tax on natural resources production was introduced for development of these fields.
The data were presented by Vladimir Ivanovsky, Professor of the I.M. Gubkin Russian State University, in his opening speach at the conference arranged in Moscow within the framework of Neftegas-2008 show. The conference was organized by the I.M. Gubkin Russian State Oil and Gas University and the Territoriya Neftegaz magazine, with support rendered by the Expocenter Central Exhibition Complex, MesseDusseldorf, and informational support by Oil&Gas Eurasia. The conference touched upon a very urgent topic: “Technologies for Oil and Gas Production and Treatment in Abnormal Operating Conditions.” Over 30 speakers presented their reports at this representative international conference, and most of them presented new technologies for hydrocarbon production and treatment in abnormal operating conditions.
In his opening speach, Professor Ivanovsky spoke about shifting towards production in the abnormal operating conditions noticed in the natural gas sector as well. In his opinion, “dry” gas production from the shallow Cenomanian intervals will inevitably decrease. At the same time, production of “wet” gas form the Achimov formations will increase; the depth of these beds’ occurrence is 3,000-4,000 meters. The cost of production of this gas is more than two times higher, but its reserves are considerably larger. The tendency is that by 2020, the volume of gas with abnormal production and treatment conditions will exceed light ‘dry’ gas.”
In the speech at the conference, Head of Gazprom Department of Gas and Gas Condensate Production o V.Z. Minlikaev considered the problem pertaining to development of hard-to-recover reserves of the Turonian deposits. Drilling of multi-branch wells is an effective technology for the Turonian deposit development. This makes it possible to ensure the maximum area of contact with the pay bed, increase drainage area and reduce differential pressure drawdown. Application of multi-branch drilling technology requires additional initial investment in equipment, but later will result in reduction of the total capital expenditures and the overall cost of the field development. Current costs are reduced as well, due to reduction of the required wells. The wellhead equipment requirements are also reduced, well sites are smaller, and negative environmental impact is reduced.
During a gas condensate deposit development, due to pressure reduction, formation losses of condensate amount to 50 percent of the initial condensate-in-place. But experiments performed at the Vuktylskoye field prove possible recovery of the condensate deposited in the pay bed.
Organization of gas, condensate and oil production and treatment in the conditions of low formation pressure, at the late stage of the field development, in case of hard-to-recover reserves and absence of the production and social infrastructure, requires not only appropriate technical solutions, but also new economic approaches, in particular differentiation of the tax on natural resources production.
Chief specialist of the NK Rosneft-NTTs Department of New Technologies V.M. Lyapunova shared the experience in application of acid hydraulic fracturing and large-volume acidizing at the fields of Stavropolneftegaz, Udmurtneft and Northern Oil. At the first stage, a complete analysis of the geological characteristics of the field and oil composition was performed, and after that they selected a method of large-volume hydrochloric acid treatment or acid hydraulic fracturing, if necessary, with utilization of surfactant systems reducing the interfacial tension, iron inhibitors, synthetic acid, anti-sludge additives and iron sequestering agents. Corrosion inhibitors and divertive fluids were also used. This comprehensive individual approach brought positive results. The increase of production rate per well amounted to 240 percent compared to the initial rates, before the treatment.
An interesting presentation was made by Vladimir Valovsky, Deputy Director of TatNIPIneft. It included several promising technologies to be used in the abnormal operating conditions at Tatneft.
Particularly, for operation of wells with asphaltene-resin-paraffin deposits, rods with fusion bonded scrapping centralizers combined with tubing with the polymer coating PEP-585 are used, which enables considerable improvement of the overhaul life of the equipment, more than three times compared to the year 2000. Utilization of sucker-rod pumps with a chain drive for the wells with high-viscosity production gives the following results: viscous force reduction by 60-70 percent, decrease of power inputs by 15-20 percent, reduction of assembly operation costs, smaller rod load, reduction of repair operations 1.5 times, and increase of overhaul period from 671 to 899 days. Since 2005, the amount of pumps with the chain drive at Tatneft increased three times. Production from the temporarily shut-in wells is performed using mobile swabbing units. These units are quickly mobilized, and can have their own tank vessel for produced crude oil loading. Various designs of swabs have been developed for the mobile swabbing units, for example, all-metal swabs or swabs with rubber fins. In 2007, 253,500 tons of oil was produced using mobile swabbing units.
Tatneft specialists also apply small-diameter well technology. With string diameters of 114 mm, costs of well construction are reduced by 30-40 percent, which makes it possible to drill more wells and increase the oil recovery factor without increasing the budget.
Head of Noyabrskneftegaz Production Department S.N. Anufriev described the problems, which the company faced applying artificial lift in case of a 3-km deep interval in the Yamal region. They include mineral salts, scale, and associated petroleum gas, as there are about ten fields in that region with high gas-oil ratio “in the range from 300 to 4,000 mcu.m/mcu.m, which creates significant hindrances for the stable operation of centrifugal pumps. All newly purchased fields have the problem of high gas-oil ratio. To solve the problem of negative effect induced by salts, a technology of inhibitor pumping downhole with the help of wellhead batching units and via the reservoir pressure maintenance system is used. Scale deposition can be prevented by using filters ZhNSh, the design of which includes centralizers to reduce the risk of filter damage while running-in the well. Jointly with Novomet-Perm, unique multiphase pump equipment was designed in 2007. It is a primary pump, which ensures reliable pump operation with free gas content at the inlet up to 60 percent. This device enables:
– compression of gas-liquid mixture and reduction of free gas volume.
– pumping of gas-liquid mixture through the main pump, thus preventing formation of slugs;
– operation in wells with abrasive material concentration up to 1, 000 mg/l due to its abrasive-resistant design.
At the same time, the gas-liquid mixture is not discharged to the annulus, but passes through the main pump. In the tubing, due to gas-lift effect, gas performs useful work increasing the unit efficiency. Today, two wells are in operation at the Vyngapurskoye field, with VNN-124 units equipped with primary multiphase pumps. They function stably, allowing a bottom-hole pressure 60 percent lower than the bubble-point pressure, and a gas-oil ratio exceeding 1,000 mcu.m/mcu.m. Early in 2008, commercial production of this equipment has started, and the company plans to install over 100 multiphase pumps.
The representative of PCM Oil & Gas in Russia Frederic Jeebert offered a new product from the company: an all-metal cavity type pump PCM VULCAIN. This pump is designed for lifting of extra-heavy crude oil at high temperature. The maximum operating temperature of hydrocarbons is 350 degrees Centigrade. The pump is capable of pumping a mixture containing up to 5 percent sand and 60 percent gas. There are positive results from tests of this equipment in Canada and Africa. The maximum viscosity of the transported liquid at which the pump pressure characteristic is not reduced is 10 000 cSt. The design is protected by two patents.
Centrilift Baker Hughes presented at the conference results of their researches aimed at production of heavy oil and bituminous sand with the use of steam.
In practice, the unit for oil production by the method of steam-gravitational drainage proved its operational capability at liquid temperatures up to 240 degrees Centigrade, which is a very good result.
We Are Still Falling Behind in Application of New Technologies
Vladimir Ivanovsky, head of the Department of Machinery and Equipment for Oil and Gas Industry at the I.M. Gubkin Russian State Oil and Gas University
Oil&Gas Eurasia: How frequently abnormal operating conditions for oil and gas production are encountered today?
Vladimir Ivanovsky: Today there are virtually no fields under production left which could be classified as good, easy in operation. Many of them have actually reached the end of their resources. Whereas the fields which are attractive in respect of geology, oil viscosity and other parameters, are located, as a rule, in the regions with non-developed infrastructure and the toughest climatic conditions. There are problems everywhere – the “easy” oil has already been recovered. This is actually a world tendency, except for the U.S. as it can buy oil abroad and conserve their own fields with good parameters for future use.
OGE: What technologies are used for abnormal production conditions?
Ivanovsky: Virtually each well requires a special technology. There are similar wells, but even with application of standard technologies, special regimes should be selected for each well.
OGE: What are the most important areas in the technology development?
Ivanovsky: First of all, it is the use of centrifugal pumps. They have already been used to produce over 70 percent of Russian oil. The oil industry started using them long time ago, but in the last three years, manufacture of various dimension-types of such pumps trebled compared to earlier period due to changed operating conditions. It became possible to use various primary devices, state-of-the-art materials, techniques for startup, shutdown, and frequency variation – higher variability for ESP.
We could also mention here technologies of thermal treatment of the bottomhole formation zone and large part of the formation under various operational conditions. The treatment is performed by injection of steam, other heat carriers, for example, water, and water containing surfactants or chemical solvents so that to improve recovery of high-viscosity oil.
Talking about the future, I would like to stress the importance of development of technologies for high-viscosity oil production. Reserves of these hydrocarbons are huge, not only in our country, but in other regions of the world as well. Their depth is not big, for example, in Tataria their depth is 70 meters and more. Absolutely different technologies will be applicable here, in some cases it is possible to use the open-cut method, by excavating bitumen-containing sand. One cubic meter of the rock contains approximately 30 percent of bitumen, and the rest is sand. These technologies are developed by Centrolift in Canada and also in our country, but they are still very costly.
OGE: How efficient is the application of hydraulic fracturing technology?
Ivanovsky: We need hydraulic fracturing badly, as what we really have is a hole in the ground, and we can recovery everything which is around this hole, but not what is located farther from it. The way out would be to drill wells with small spacing between them, which is too expensive, or to apply technologies which would ensure fluid movement in the reservoir. Here the hydraulic fracturing technology can be very helpful, if necessary, with acid or with special proppants. However, hydraulic fracturing sometimes changes the bed so much, that it could be very difficult later to find pieces of the originally discovered bed.
OGE: How does this technology meet the ecological safety requirements?
Ivanovsky: Just imagine, acid is being injected. Will all this acid get into the formation? Definitely not all – there is no hundred percent guarantee that casing strings are leak proof. That’s why when I was working in Tataria several years ago, it used to happen that I would come to a familiar water spring, and it was impossible to take water from that spring. It was either salty or acidic. Lately much more attention is being paid to the ecological issues; much has been done to improve the situation.
OGE: Do our producers fall behind their werstern counterparts in terms of technologies use?
Ivanovsky: We fall behind mostly in the advanced technologies use. The hydraulic fracturing technology, for example, was developed back in the Soviet time; multibranch wells and horizontal drilling were designed here as well. We lack not funds, but the political will of the management of the companies, if anything. None of the companies will invest a dime, if return on investment in this or that project is expected in more than two years. Top managers of the companies do not go as far as these decisions, preferring short-term projects.
Tatneft Joins the Best in Application of New Technologies
Deputy Director in Research Work of TatNIPIneft Vladimir Valovsky
Oil&Gas Eurasia: What makes oil and gas production in abnormal operating conditions especially interesting?
Vladimir Valovsky: This is related mostly to the time of the field development. Most fields operated by Tatneft have passed over to the late stage of development. This year it will be 60 years since the beginning of the development of the unique Romashkinskoye field. Before, oil was flowing, now it is 100 percent artificial lifting. But with regard to production dynamics, Tatneft is the only company, which was able to sustain the production at the same level and even get some production increase during the last ten years.
OGE: How a technology for each particular well is selected?
Valovsky: First of all, it is determined by economical aspects. The company has a developed calculation mechanism, to do calculations of the profitability index, payback period, and other economic criteria for each field. Only after financial appraisal of the project, appropriate funds could be allocated for it.
OGE: What new technologies your company uses?
Valovsky: The company uses the technology of simultaneous selective-zone production in one well, which enables cost reduction and increase of production rate. We have now over 200 wells with dual completion system: in case if the well penetrates two productive beds, they are separated by a packer and, with the help of special technical devices, selective-zone production is realized, with different production rates and different pressures. This helps to save on drilling of additional wells.
Besides, now we are performing active work on small-diameter well technology.
The string having the diameter 114 mm makes it possible to reduce the cost of well drilling by 30-40 percent compared to the conventional wells. Accordingly, with the same amount of money, it is possible to drill more wells, to infill the well pattern, and improve the oil recovery factor for the same area.
OGE: How do you solve the problem of the associated gas utilization?
Valovsky: About 95 percent of the associated gas is utilized at Tatneft; the Romashkinskoye field is 99 percent covered by the system of the associated gas gathering for the Minibaevsky gas processing plant. In this respect, we are second after Surgutneftegaz.
But new, remote fields are not covered by this system yet; it is not economical to lay pipelines from these fields to the plant. It is planned to build gas-fired power plants at the remote fields, which will generate electric power for the local needs at the field. Another area of work is utilization of the associated gas to produce heat for high-viscosity oil treatment processes.