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№ 11 (November 2006)
Established in 1992, Russian Innovation Fuel-and-Energy Company (RITEK) has been focused on provision of high-quality services to the Russian hydrocarbon-producing companies.
It became an adequate competitor to the western companies in the area of rehabilitation of the inactive (temporarily shut-in) wells. The profit of the innovation company increased due to incremental production, achieved by using RITEK's advanced development works at the oil fields of LUKOIL, Tatneft and Rosneft. When RITEK made a decision to create its own mineral resources base, it received fields with a complex reserve structure. Then the experience gained in the course of this contractual work and the considerable stock of developed technologies proved useful. At present, RITEK possesses the right to 55 objects of intellectual property. Being one of the leaders in the oil sector in the oil production growth rates (20-30 percent a year), RITEK leaves behind many big companies.
One of the largest acquisitions of the company - Sredne-Khulymskoye field, is located in almost impassable swamps, in the permafrost zone of the Yamalo-Nenetsky Autonomous District. This field, having been placed in production in 2002, provides considerable incremental oil production compared to the other fields of the company. Almost 1 mln tons of oil was produced from this field last year. High performance is ensured not only by the so-called "early age" of the field, but also by the application of advanced technologies.
To improve the oil recovery factor and increase volumes recovered at the Sredne-Khulymskoye field, in 2004, researchers of the Institut Francais du Petrole developed an engineering design for drilling of horizontal wells, which took into account a number of technical and economic parameters. The first horizontal well in the most complex central part of the southern block of the field was drilled in 63 days and completed with the participation of the general contractor for the project - the Schlumberger service company. The well put in operation by RITEKNadymneft produced daily 420 cu. m of oil. This number is 10 times higher, compared to the estimated performance of a straight directional hole in this license block. The first well enabled verification of the geological structure of the field and improvement of the production level. It was followed by two more wells drilled in 2004, with 800-900 m horizontal hole length. Another two wells were drilled early the next year.
Successful experience in horizontal hole drilling enabled the Company to initiate development of the hard-to-recover reserves of the Sandibinskoye field, also located in the Yamalo-Nenetsky Autonomous District. In September of that year, the First National Drilling Company completed drilling of a development well with a horizontal bottomhole section on the Ob Bay shore. Its depth exceeded 3,000 m, and the length of the horizontal section along the pay bed exceeded 400 m.
However, RITEK did not stop at this point. Utilizing the experience in horizontal drilling, they performed operations on rehabilitation of 15 oil wells by sidetracking.
"The company's well stock is not very large that is why we are fighting for every well," said Alexander Ivanenko, head of the well drilling technical support department at RITEK. "We have got a 90 percent water encroached well at the Sredne-Khulymskoye field, with water present in the upper horizons. All attempts to 'cure' this well failed. Then a decision was made to sidetrack the well in the other strike. We drilled the hole eastwards, and the well produced clean oil." This rehabilitation of well No. 579 by drilling of a lateral horizontal hole was performed by the First National Drilling Company for RITEK in August of 2004. The operations were performed from the mobile drilling rig ARB-100. Total depth of the lateral horizontal hole was 3,070 m, its length - 580 m.
"Finally we realized that existing not-depleted zones should be developed with the use of sidetracking, whenever possible," said Ivanenko. "We fixed up wells with downhole problems, rehabilitated wells, production from which had not been profitable (amounting to 2-3 cu.m per day). As the result, we came to the practice of preliminary planning: the direction of the lateral hole is defined beforehand. The Company's Research and Production Center on Geology, Design, and Improvement of the Field Development Technologies provides recommendations on potential efficiency of this drilling method."
Apart from the First National Drilling Company, such companies as Kogalymnefteprogress, Krasnoleninskneftegaz, and Aznakaevsky Horizon are contracted for sidetracking operations.
RITEK's subsidiary, Kogalymnefteprogress, came to sidetracking specialization after performing operations in well workover. "Early in 2004, RITEK management made a decision on organizing operations related to lateral hole drilling in Kogalymsky region of West Siberia. Therefore, we had to train our specialists in technology and drilling practices, to run-in and adjust drilling equipment, and to select a contractor for navigation support," said Mindiyan Khalimov, first deputy general director of Kogalymnefteprogress. Eight lateral holes with horizontal bottomhole sections were drilled from 2004 to 2006 at the fields of RITEKneft. One crew has been working in the stable regime, two more crews are at the stage of gaining experience.
During nine months in 2006, operations on well rehabilitation by drilling of lateral holes with horizontal sections have been performed in three wells of the Company at the Kurraganskoye and Vostochno-Perevalnoye fields.
"We spent the longest period of time (60 days) on drilling a well at the Kurraganskoye field, but this was due mostly to a complicated meteorological situation: very low temperatures were observed at the beginning of the year," said Yaroslav Legaev, head of the geological department of Kogalymnefteprogress. "Originally the well was directional. By the moment of shut-in, its production rate was 2 cu. m/day, and water cut - 87 percent. Early in March, based on the results of the fluid level buildup, we managed to run in the downhole equipment, pressurize the wellhead, perform pressure testing and start the well." After relocation of the drilling equipment to the Vostochno-Perevalnoye field, wells No. 412 and No. 501 were sidetracked that took 48 and 40 days respectively.
At present, RITEK is performing sidetracking not only at the oil fields in West Siberia, but also in Tatarstan. Wells in Tatarstan are not so deep; therefore, drilling operations are easier and take less time.
"The process is labor-consuming, and sidetracking takes about from 30 to 50 days. If just one crew performs such operations in the region, it would be difficult to drill more than ten holes per year. However, these numbers correspond to RITEK's actual demand in this technology. Our well stock amounts to several hundred wells, which is much less than Surgutneftegas', for example. The more wells we drill in future, the more probable it will be that one or two wells out of the ten drilled will not be profitable. They will have to be sidetracked," says Ivanenko regarding the potential of this line of activity for the company.
At the same time, the specialist believes that selection of a drilling method depends on the field in which it is supposed to be applied. "If there are beds with good reservoir properties, then drilling of horizontal holes will be really promising, as production rates could increase three to five times. But most of the reservoirs have a complex structure; therefore, one cannot state undoubtedly that sidetracking or horizontal hole drilling is a "cure-all" solution. All methods should be used." .