№1 January 2012Table of contents Issue Archive
№1 January 2012Table of contents Issue Archive
№ 8 (August 2008)
First discovered in 1943, Tatneft’s Romashkinskoye oilfield was the first of Russia’s mega fields of platform type geology to be produced using contour waterflooding. Data gleaned in 1943, however, was not all that impressive and it took a second look, in 1948, to discover the Devonian layers where 90 percent of the field’s reserves were hidden.
First discovered in 1943, Tatneft’s Romashkinskoye oilfield was the first of Russia’s mega fields of platform type geology to be produced using contour waterflooding. Data gleaned in 1943, however, was not all that impressive and it took a second look, in 1948, to discover the Devonian layers where 90 percent of the field’s reserves were hidden. Initial reserves were estimated at 3,922 million tons in an area covering 425,000 hectares. Sixty-five years on, Romashkinskoye is still in production, pumping 15 million tons a year to market. As Oil&Gas Eurasia’s special “Salute to Oilmen’s Day”, we offer here a retrospective on this grand “old man” of an oilfield.
The history of oil discovery in Tatarstan, and in particular, discovery of the Romashkinskoye field, is truly dramatic. It relates closely to the development of concepts of oil formation and accumulation. That is why the prolific Romashkinskoye field was discovered more than once.
In Tataria, as Tatarstan is traditionally called, oil seepage at the surface was recorded a long time ago. This was the main petroleum search factor at the first stage of the petroleum geology development. However, drilling had negative results for a long time. When the communists came to power, several expeditions were sent to this region (with the participation of Ivan Gubkin) in the period from 1918 to 1924, but all of them failed. In 1925, the Geological Committee of the Supreme Economic Council – the main Soviet geological exploration agency, wrote in its Review of the USSR Mineral Resources about fields located between the Volga River and the western slopes of the Ural Mountains: “In respect of oil production, all fields in that area are of no special interest.”
Geologists grouped into supporters and opponents of the Ural-Volga oil. The second half of the 1920s and the first half of the 1930s was spent on the so-called rehabilitation of the “second Baku” (this name the Ural-Volga oil-and-gas bearing province received at the suggestion of the USSR chief petroleum geologist Ivan Gubkin). In late 1920s, oil exploration was resumed, and oil was discovered on the territory of the modern Perm and Samara regions and the Bashkortostan Republic. However, search for oil in the very heart of the “second Baku” – Tataria – kept failing, though there were indirect signs of oil presence. At one of the meetings in 1936, Ivan Gubkin signed a decree which stated: “Abundance of oil shown in the form of tar sand and availability of structures favorable for oil accumulations put Tataria among promising oil bearing regions.”
However, oil beds in the traditional oil producing regions of the former Russian Empire, such as Apsheronsky and Severokavkazsky, were located significantly shallower compared to the Ural-Volga oil-and-gas bearing province. The search for oil in the Ural-Volga region demanded from geologists courage directrly proportionate to the depths of exploration targets – Permian, Carboniferous or Devonian. Under Stalin’s regime, a “dry” well could cost the misfortunates a “trip” to remote northern fields. This cruel dependence restrained initiative even when the state allocated sufficient funds for exploration. Technologies, which would enable drilling to those horizons, had not been refined yet. There was no appropriate equipment available, and all existing equipment was sent to more perspective areas. In late 1930s geologists working in Tataria complained of desperate shortage of materials, funds and skilled personnel.
The country urgently needed new oil fields when the Second World War broke out and Germany attacked the Soviet Union. There appeared a threat of occupation of the Grozny and Baku oil fields. The State started to hastily relocate the equipment and personnel from those regions to the “second Baku”, but the Main Geological Department of the People’s Commissariat of the USSR Oil Industry (Narcomneft), which controlled oil exploration, made a number of strategic mistakes. The very scarce drilling rigs, pipes and those specialists who had not been drafted yet were sent to various regions, even to Yakutia, but not to Tataria. On March 28, 1942, the geological service heads were replaced at the meeting of the Narcomneft Board. Then, operations in Tataria became more active and yielded positive results.
On June 25, 1943, the exploration well #1, near Shugurovo village, penetrated the Verei-Namyurskian deposits of the middle Carbon at the depth of 617.5 meters, with the first oil shows. The oil flow rate was gradually increasing and reached 20 tons per day by August, enabling Tataria to prove its right to the “title” of oil bearing region.
The new field received the name “Shugurovskoye”, and none of the geologists realized at the time that only the first step to discovery of an oil giant had been made.
Five years later, again in June, Romashkinskoye field was “re-discovered”.
In July of 1946, exploration well #3 with a planned depth of 1,800 and later 1,970 meters, was staked 20 kilometers away from the Shugurovskoye oil field, near Romashkino village (not far from the modern town of Leninogorsk). It was drilled in the period from January 31, 1947 to May 31, 1948. The drilling log book has only a brief record of this truly important event, giving a list of performed technological operations. On July 10-11, 1948, they started perforating the casing, and on July 15 the well was completed.
The start of oil production at the Romashkinskoye field was far from stunning. The formation, damaged in the course of drilling, was in no hurry to produce an oil flow. No oil shows were recorded in 24 hours. On July 16, early in the morning, gas, clay mud and some brown liquid started coming out of the open gate valve. It was the first Devonian oil of Romashkinskoye field. In a few days, the oil production rate reached 120 tons. This was quite a surprise for the leaders of the country, who soon afterwards awarded the Stalin Prize to the discoverers of Romashkinskoye field. But they were even more surprised, when additional exploration of the field was commenced.
On December 14, 1949, the People’s Commissar of the Oil Industry Nicholay Baibakov wrote to the Deputy Chairman of the USSR Council of Ministers, the former People’s Commissar of the Interior Lavrentiy Beriya (published for the first time): “I report to you on the results of testing of well #1 at the new Minnibaevo field in Tatarskaya ASSR. The Minnibaevskaya area is located 48 kilometers north-east of the city of Bugulma and 15 kilometers in the same direction of the Romashkinskoye oil field. Exploration well #1 at Minnibaevo penetrated two oil beds in the Devonian deposits. […] Well #1 is a discovery well of a new commercial Minnibaevskoye field in Eastern Tataria.”
Only much later the geologists realized that the Minnibaevskoye, Aznakaevskoye and other discovered fields, including Shugurovskoye field, were parts of the single super-giant Romashkinskoye oil field.
The Water Flooding Method
In late 1940s, the main economic criterion of oil production in the war-devastated country was “to satisfy the country’s need in oil and oil products at the lowest possible costs and with the highest possible recovery rate.” There was an acute shortage of funds for restoration of plants and factories, as well as of equipment and accommodation. Yet, technologies offered by petroleum experts required large quantities of metal. Designers of the Romashkinskoye field development had to save on everything. Head of the Main Department of Oil Production in the Eastern Regions at the USSR Oil Industry Ministry (the new name given to People’s Commissariat of the Oil Industry in 1946) N. Timofeev formulated that economic criterion for the designers, as follows: “We know that we won’t get the desired amount of capital investment while the set oil production goals will remain the same, or maybe even get bigger. Thus, roughly estimated, several billion rubles will be lacking. Given the situation, how can we bring down the costs?” A special commission was set up at the Ministry, which was tasked to find ways to reduce capital investment in the oil field development; it had to devise special economic measures by reducing the supply of necessary equipment to workshops and labs, etc.
The country had extensive plans. In 1945 the USSR produced nearly 19 million tons of oil. Yet, in 1946 Joseph Stalin promised his fellow countrymen to increase oil production up to 60 million tons in 15 years, i.e. by 1960. Nobody knows what calculations made up the basis for those forecasts as at the time no wells at Romashkinskoye field had been staked yet. However, when drafting of the master plan for Romashkinskoye field’s development was still at the commencement stage, the target numbers became much higher as the country leaders became aware of the discovered field’s actual value.
Scientists understood that given the need to achieve maximum production with minimum investment, initiation of flooding would be the most rational method to use. It suggests water injection into formation at the very start of development to extend the period of well flowing. The idea appeared at the beginning of the 20th century, but the first lab and later production tests were initiated only in 1930s both in the Soviet Union and in the U.S. Since 1936, the East Texas field in the U.S. has been developed using the edge water flooding, but it was employed as the secondary field development method. Since 1946, they started using that method at the USSR’s then largest oil field – Tuimazinskoye, and later at several other large fields.
Development of huge oil bearing area without water flooding would have taken hundreds of years. Application of edge water flooding would reduce that period, but the field’s central part would be suspended for a long time. In 1952, maths professor at the National Research Institute of the Oil and Gas Industry (today A.P. Krylov VNIIneft) N. Piskunov offered a bold idea: to inject water in the very center of the oil pool. Injection wells were supposed to divide the field into several dozens of separate areas. Thus appeared the idea of boundary water flooding, which made up the basis for the Master Plan of Romashkinskoye field development.
The first Master Plan (in total, there were four of them) was prepared by a group of VNIIneft specialists and was approved on May 18, 1956. Technically, it was based on the following elements: the initial boundary water flooding, a wide well spacing, a two-stage drilling, and consolidation of production targets.
Professor G. Vakhitov, director of VNIIneft in the 1980s and former director of Tataria institute TatNIPIneft, noted that all elements of the Master Plan were “new, not self-evident and required serious trial in the field.” However, the designers did not have sufficient time for such a trial, given the grand oil production goals. Still, according to Prof. Vakhitov, implementation of the main elements at the first stage “enabled stimulation of oil production and improved the country’s economic status considerably.”
The first Master Plan of the Romashkinskoye field’s development gave rise to a wide discussion, which benefitted not only the Soviet, but also the world petroleum science. The main issues under consideration included well spacing and its effect on the reservoir recovery; selection of production targets and hydrodynamic connectivity account for different oil bearing horizons; the amount of water produced together with oil; the injection pressure value, chemical composition and treatment of water to be injected into formation, etc.
Well spacing remained the core issue. At that time scientists all over the world, the U.S. included, believed that well spacing had no effect on the oil recovery. That is why they thought that it did not make any sense to drill really close-spaced wells. Why should more money be invested in drilling, if oil will be recovered anyway? It was proposed to use a denser well pattern for the highly productive central areas of Romashkinskoye field, and a wide well pattern for less productive marginal areas. On the whole, it was planned to drill one well per 41 hectares of the field area, but actually the area appeared to be even larger. The first Master Plan envisaged drilling of 9,200 wells, including 2,900 reserve ones. Yet, Professor R. Muslimov, who headed Tatneft’s geological service for many years, suggested based on estimates that over 24,000 wells had to be drilled to get the planned oil recovery factor.
Right from the start, insufficient amount of wells resulted in lower efficiency of the field development system, as only half of the initial recoverable reserves were swept by the water flooding system. A single injection front quickly disintegrated into various “break-throughs”, when oil was displaced from the most permeable zones, and great amounts of oil were “sealed up” in the low-permeable zones. The water cut of the produced oil increased significantly and, in consequence, the load on the field pipelines became higher, and considerable investment was required to build oil demulsification facilities, etc.
Compared to the first Master Plan, all subsequent development plans had been amended significantly. Of the 11 main principles initially included in the design work, only the boundary water flooding and the order of injection wells completion remained in the Plan. The aim of all amendments was to make the flooding process more controllable and efficient.
Specialists of Tatneft and the company’s R&D institute, TatNIPIneft, were the main force to deal with the task. Tataria’s scientists and engineers offered new methods of water flooding including focal, block-contour, repeating-pattern, selective, and other methods, which would make it possible to take into account the reservoir heterogeneity and to control water movement and oil displacement.
As a result of application of new technologies for oil field development, the targets set by Joseph Stalin were exceeded. In 1960, over 147 milion tons of oil were produced instead of 60 million. As the oil industry historian M. Slavkina stated, thanks to “cheap” oil of the Ural-Volga region, the so-called “transport revolution” took place in the country, with rapid development of automobile and air transport, as well as of machine-building sectors of the economy. The motor industry, aircraft construction, and related metallurgic sectors moved to a higher level; freight turnover and passenger operations increased; and on the whole, the living standard of Soviet people improved considerably.
In 1962, the group of designers of the Romashkinskoye field’s development plan was awarded the Lenin Prize, one of the most prestigious Soviet awards.
The Unfading “Romashka”
The mature field continues to surprise people with new discoveries. Today it plays a test field part for extensive pilot projects to help scientists resolve problems of carbonate reservoir development. At present, various enhanced oil recovery methods are used for field development, based on flow-deflecting technologies, wave methods of formation treatment (vibrators, etc.), physical methods (hydraulic fracturing, horizontal and multi-wellbore drilling). But the actual proof of the field’s reserves replenishment came as the biggest surprise to Tatarstan petroleum experts. Following ten-year studies, Professor Muslimov has reached a conclusion that Romashkinskoye field’s reserves are increasing due to hydrocarbon migration from the crystalline basement, the zone “a priori” closed for oil. Thus, this petroleum “asset” will provide us with the valuable raw stock for many more years. But as any asset, it needs care.