V. Sigitov, D.Batyrbekuly

THE APPLICATION OF EXPANDING CASING TECHNOLOGY

FOR OPEN HOLE LINER

Nowadays the situation of oil and gas extracting world industry is characterized by investigation of remote deposits with severe climate conditions. It means we can observe necessity in increasing of drilling depth and casing length, and complication of the geological quarry conditions. Thus, the most important and actual problem is the preservation of well bore diameter, hydraulic isolation of permeable bed, increasing the exploitation time of the well and its economic workability. The solution of these problems with the help of traditional technologies is becoming more and more difficult and capital-intensive, especially when dealing with complicated geological conditions or deep water drilling. The cardinal solution to the mentioned problems can be the refusal from the traditional wells and the construction of monodiameter wells, applying the technology of expandable casing.

In this article the application of this technology for an open well liner is considered. There's a sequence of expanded liner installation and the principle of the technology. The advantages of the technology are: transition to a new design of a wellbore, providing decrease in diameter and quantity of lowered columns; decrease in a waste of drilling and quantities of materials; possibility of application of smaller geometrical parameters and decrease in expenses of energy and emissions in atmosphere; building the well with the superbig withdrawal from a vertical. In the basis of an expansion principle there are two technologies:one exclusively Russian one hydraulic expansion of a profile part of the pipes, the second is applied everywhere, both domestic, and the foreign companies, mechanical expansion the basis of which is a cold processing, steel pipes are expanded in a borehole of a well till the demanded diameter.

Open hole liner is used for overcoming of working problems, such as instability of walls of a well, incompatibility of conditions of drilling on gradients of bed pressure and pressure of hydrorupture of a layer, influence of saliferous formations or the layers, all these complications in the process of drilling can lead to reduction of diameter of a wellbore. The expanded system goes down through existing casing string, settles down in the range of an open borehole and then extends in a direction from below upwards. From all cases of application of expanded trumpet products the well of one diameter through passage (Monodiameter, Monobore wells, Slender wells) has the greatest potential. The idea consists in establishing expanding liners consistently one after another.

One of perspective directions of monodiameter technology is building of wells with the big deviation of a face from a vertical (Extended Rich Drilling ERD). The system of building the wells of one diameter of a borehole through passage with the big extent in a lateral direction will be used for the same reasons on which usual drilling of wells with the big displacement of a face from a vertical is carried out. The analysis of technical practicability of the project by working out of building of wells has been executed for one

large operator in the North Sea as a part of preliminary engineering study and designing. This analysis covers an existing oil deposit and the project of working out of a deep-water gas deposit planned for the near future with usage of wells with underwater armature. Comparison of usual drilling and usage of expanded casing strings has been thus executed.

Research has shown possibility of increase in extent of lateral boreholes on 25-100 % with reduction of danger of occurrence of problems at drilling on both deposits. Other researches of technical characteristics of drilling and expenses for drilling on the same North Sea deposits have shown that cost of the drilled well and drilling time can be lowered, at least on 25-30 % thanks to application of technology of building of a well of monodiameter through passage.

Expanded trumpet products should meet the demands of strict norms, surpassing norms for usual pipes. Along with metallurgy it is necessary to supervise rigidly deviations from nominal internal diameter. Besides, defects of internal and external surfaces can operate as a point of a priming for formation of cracks at metal expansion. These problems managed to be overcome appreciably partly thanks to the cautious treatment.

Nowadays the solution to a problem of preservation of high resistance to pipe deformation after their expansion is not reached yet. Researches in a direction of working out of stronger, steady and cheap expanded trumpet products with tight connections for gas and the raised durability to rupture from internal pressure, and also improvement of an expanding cone therefore proceed. Till now the practical limit of plastic deformation without risk supposes the degree of expansion of 30 %. This condition imposes restriction on a range of applied pipes.

It must be mentioned that there're not so many foreign companies, investigating the technology of expanding casing, they are primarily large service companies, such as Halliburton, Schlumberger, Enventure, Weatherford, Baker Oil Tools, READ Well Services. The analysis of possible application of technology on Prirazlomniy oil deposit showed a considerable simplification of a design of a well and reduction of expenses as a result of reduction of volumes of dump on 46 % (9,5 thousand ?3, or 25 thousand tons), weights of casing string on 63 % (13,3 thousand tons), cement volumes on 77 % (8,7 thousand tons) is resulted. At technology usage there's a decrease on a derrick from weight of the heaviest column on 33 % (with 450 to 300 tons) and consequently, the increase in length of a borehole of a well on the tool is possible. Besides obvious reduction of the expenses caused by decrease of quantity of wastes, required quantities of a cement mortal and metal consumption, technology application allows to increase the speed, to apply less powerful equipment, to reduce considerably the expenses for transportation of the equipment and materials. Besides a direct economic gain in comparison with traditional multicolumn well, the technology will allow to spend well on the big depths, wells with the big deviation of a face from a vertical in difficult mountain-geological conditions, to build wells in nature protection zones etc.

It is necessary to notice that not only theoretical researches and modeling in the field of building of wells with a monodiameter are proceeded, but also some practical tests. Building of a well with two short expanded liners of one diameter by joint efforts of companies Shell Exploration and Production Co was the first step in experiments on practical application of technology. Shell International Exploration and Production Inc. and Enventure Global Technology in the middle of 2002 in district of Southern Texas applied the technology to a design of a well Thomas Rajf 15. In spite of the fact that experiments on practical introduction of technology were rather labor and time consuming, they have confirmed practical possibility of building of wells with a monodiameter, and after improvement of technology it will allow to reduce expenses for building and to provide conducting of a borehole of reasonably big internal diameter on all length to unprecedented depths. At present rates of works the full introduction of monodiameter technology requires at least five years. Nevertheless, for achievement of this purpose various researches and trade experiments are conducted continuously.

Thus, in the given work possibilities of application of effective technology of drilling and major repairs of wells by means of expanding casing are stated.

References:

1. A. Shvakov, R. Volkov. The latest perspective innovations: technology of monodiameter.// World Oil, July 2006.

2. ВеИ R., McKee R., Zward E., Lewis D., Suryanarayna P.V. Single-diameter technology capable of increasing extended-reach drilling by 50%.

4. Dean B., Cook L, Brisco D. Monodiameter drilling liner from concept to reality, SPE/IADC 79790, SPE/IADC Drilling Conference, Amsterdam, Netherlands, February 19- 21, 2003.

5. Jabs M. Using expandable metal technology to create a monobore well, OTC 16670, Offshore Technology Conference, May 3-6, 2004.

6. Fisher PA. Monodiameter wells continue to expand possibilities. // World Oil, July 2006.