№7 July - August 2009
№ 8 (August 2008)
At present, wide-scale construction and operation of inter-settlement gas pipelines continues developing in Russia. In all European countries, underground gas pipelines are constructed and reconstructed mainly of polyethylene (PE) pipes and fittings.
At present, wide-scale construction and operation of inter-settlement gas pipelines continues developing in Russia. In all European countries, underground gas pipelines are constructed and reconstructed mainly of polyethylene (PE) pipes and fittings. Now, domestic gas consumers have also appreciated their simplicity of operation, lifetime and efficiency. In Russia, construction of PE high pressure gas pipelines of category I was restricted until recently by a safety factor of Кs=2.5 specified by safety standards developed in 1990s. Proceeding from 15-year experience in operation of PE gas pipelines in Russia and a need to integrate standard vital issues, it was decided to develop a regulatory document that would allow arrangement of activities relating to construction and operation of gas pipelines under pressure up to 1.2 MPa. In the course of developing the mentioned document, Polimergaz relied on advanced domestic and foreign experience in the area of design, construction and operation of PE gas pipelines. Arrangement Standard (STO) STO 45167708-01-2007, Design and Construction of Polyethylene Gas Pipelines under Pressure up to 1.2 MPa and Reconstruction of Worn Gas Pipelines, has become a master permissive document that starts the new era for construction of modern PE gas pipelines. This document was highly estimated by Rostekhnadzor of Russia.
A scope of work performed was justified by urgent practical expansion of the area of PE pipes application, especially for inter-settlement high pressure gas pipelines of category I. A decided and particularly important advantage of this development is that more gas can be transported using the same pipe diameter.
These changes enable new scopes of design and construction operations pertaining to inter-settlement gas pipelines. It is worth mentioning here that Zapsibgazprom gas holding and its industrial and installation subsidiaries have more than once pioneered application of up-to-date solutions in construction of modern PE gas pipelines and demonstrated their professional competence.
One of the largest among such projects is construction of an inter-settlement PE high pressure (up to 1.2 MPa) pipeline from the settlement of Baikalovo to the settlement of Turinskaya Sloboda in Sverdlovsk region. An experienced and reliable general contractor was required to perform the construction. Zapsibgazprom is a reputable company with extensive experience in construction of polyethylene pipelines of various types, including high pressure gas pipelines; that is why it was charged with the task. Construction of this gas pipeline complied with requirements of all regulatory documents. Immensity of the project is confirmed by performance of complicated tasks such as construction of 14 undercrossings of rivers, streams and highways of categories III and IV, by means of directional drilling, with a total length of 1,600 m. Implementation of this non-typical project required an absolutely new approach – arrangement of activities within the framework of improved technology of high pressure gas transportation. It was necessary to improve organizational culture and work performance discipline. Construction rules and regulations were strictly complied with, both for the construction as a whole and for the project’s individual stages. Unique products developed by Sibgazapparat plant, a subsidiary of Zapsibgazprom, were used to construct the gas pipeline. These products include PE pipes of polyethylene grade PE 100 SDR 9 Do=315, 225, 160 mm and permanent connections PE/St, the best in the market of polyethylene pipes designed for gas transportation. At present their large scale production has been launched.
The main linear part of the gas pipeline was installed by June 2007, and then final assembly of all surface structures was carried out. After completion of testing, the gas pipeline Baikalovo – Turinskaya Sloboda was officially put into operation. This high capacity gas pipeline nearly 60 km long is much more than just another large-scale project – it is a vital source of heat continuously supplied to consumers.
OPTIMASS Flow Meters to Enable Crude Fiscal Metering in the Oil and Gas Industry
KROHNE offers a solution for the accurate flow metering in the oil and gas industry. Introduction of OPTIMASS 2000 model has completed the series of Coriolis mass flow meters.
Based on its long experience of straight-tube flow meter production, KROHNE developed OPTIMASS 2000 flow meters with twin-tube for precision metering of high flow rates. All components of OPTIMASS 2000 flow meter contacting with the measurable medium are made of stainless steel UNS 31803. The instrument is supplied complete with standard flanges having diameters up to 12 inches. The instrument is rated for pressure up to 150 Bar at flow rates up to 2,300 tons/hour with 0.1 percent accuracy.
Thanks to its capability of low flow rate metering, OPTIMASS 2000 makes it possible to prevent formation of static stress while ensuring high accuracy of metering in the oil and gas industry. The capability of low flow rate metering is also an advantage for crude fiscal metering in this sector.
OPTIMASS 2000 is used with MFC 300 converter and can be supplied in the package and separate versions. Signal transformation is performed by the touch-sensitive electronics, directly at the sensing cell, where analog signals are digitized and via MODBUS RTU are transmitted to the signal converter. This architecture enables dual retention of calibration data. In applications requiring no display, this instrument can communicate directly with the system of the processor control by means of DDC (direct digital communication).
Plasma Impulse Excitation Enhances Oil Recovery from Productive Formations
Today in Russia most of large oil fields are characterized by significant recovery of reserves. Besides, a high water cut level considerably increases the amount of idle wells.
There are many methods to stimulate productive formations to enhance hydrocarbon recovery by increasing reservoir pressure, improving in-place permeability, or reducing viscosity of the produced oil. Yet, these methods have one essential disadvantage – all of them are highly specialized and target only specific problems.
In late 1990s, a group of Russian scientists headed by professor А. Molchanov launched a research program. The program’s goal was to find a source of directed impulses with power exceeding reservoir pressure. This power would create high temperature and would be capable of instantaneous compression, expansion and multiple repetition; it would also be controllable and create oscillations in gas-liquid medium with a frequency coinciding with frequencies of the productive formation’s individual layers. The task was set to enable working with any reservoirs, in wells with any water cut level.
In the course of studies and patent research, the scientists abandoned conventional methods of bottom-hole treatment and found a solution to the problem using nonlinear systems including systems with significant energy content and energy liberation, high velocity and high temperature processes, oscillations, and waves with significant amplitude.
First of all, periodic disturbances in gas-liquid medium were calculated and defined; these disturbances lead to an effect of resonance vortex formation, cavitation and flotation. As a result, liquids migrate from stagnation zones (blocks) to wells, improving in-place permeability, and concurrently treated medium is pumped with resonance energy.
This gave rise to an idea of developing a plasma impulse generator that was tested in the fields with complicated terrigenous and carbonate reservoirs in Russia, China and Kazakhstan.
Experience proved that plasma impulse excitation increases bottom-hole zone permeability and improves hydrodynamic communications between the oil formation and bottom-hole, which is also confirmed by geophysical results before and after treatment.
A distinctive feature of plasma impulse excitation is the initiation of resonance oscillations in productive formations, which prompt oil to migrate towards producing wells.
High voltage current (3,000 V) is applied to electrodes isolated by a gage wire, which results in its explosion and creation of plasma in an enclosed space.
Release of directed energy in significant quantity causes the following effect:
release of heat up to 25,000 – 28,000 С (for a period of 50-53 microseconds);
formation of a shock wave with a significant excessive pressure, which considerably exceeds the reservoir pressure;
due to processing limits a shock wave is propagated through perforations directionally along the channel profiles;
being multiply repeated, the shock wave impacts hard formation matrix in the elastic gas-liquid medium and causes longitudinal and transversal (shear) waves, which transform in a series of sequential elastic oscillations with a frequency ranging from 1 to 12,000 Hz;
being in the elastic state, the reservoir represents a combination of oscillating systems, and as a result sequential impulses cause natural formation oscillations within resonance frequencies.
A resonance effect created in the reservoir results in positive flow rates in neighboring wells. Available results prove that wells in terrigenous reservoirs react at a distance of 250-300 meters from each other; in carbonate reservoirs with a high bulk modulus, positive flow rates is registered in wells located at a distance ranging from 700 to 1,500 m. Alongside with that, the water cut level is usually reduced in all wells.
In addition to large scale excitation, creation of plasma makes it possible to solve local problems relating to bottom-holes cleaning. Instantaneous expansion of plasma creates a shock wave and its subsequent cooling and compression results in flow back to the well through perforations, which at the initial stage of well treatment contributes to removal of clogging substances to the well bore.
Since 2007, commercial introduction of the plasma impulse excitation technology is realized by Novas Company.
Cathelco Corrosion Protection for Arctic Drilling Platforms
Two massive semi-submersible drilling rigs, designed to operate in the arctic conditions of the Barents Sea, will be protected against corrosion using Cathelco Jotun cathodic protection systems. In addition, Cathelco will be supplying marine pipework anti-fouling systems to protect seachests and pipework against bio-fouling.
The rigs will be constructed at the Vyborg yard in Russia for Gazflot, a subsidiary of the Russian energy giant Gazprom. The order for the Cathelco equipment has been won by Marine Bridge & Navigation Systems, the company’s well established agent in St Petersburg.
The semi-submersibles are based on the versatile Moss Maritime CS 50 design. Cathelco Jotun has supplied cathodic protection equipment for Moss Maritime platforms in the past and this experience has led to the new contract.
According to Kevin Ward, Cathelco Jotun’s sales manager, the company is delighted to have received the orders for both the cathodic protection and anti-fouling systems on the strength of its experience in this field and the on-going relationship with Moss Maritime.
The semi-submersibles have a displacement of 55,000 tons and are designed with two 118 meter long pontoons with six stabilising columns supporting the upper hull in conjunction with four horizontal and diagonal trusses.
Because of the arduous operating conditions, the central part of the rig consists of a riser column to protect the riser from damage by pack ice.
According to Aneel Mumtaz of Cathelco Jotun, who has been responsible for the technical aspects of the project, in terms of the cathodic protection system, the riser column increases the size of the surface area and this has been taken into account in this design.
Aneel explained that, “in this rig the complex geometry, especially around the bracings and riser column, might create a potential ‘hot spot’ vulnerable to ‘under protection; despite the ICCP system providing optimum protection to the whole structure. This issue has been overcome by placing sacrificial anodes to the ‘hot spot’ areas eliminating any risk of ‘under protection’ to the structure due to its complex shape.”
He commented that Cathelco Jotun would be supplying four 800 amp ICCP thyristor control panels serving a total of 12 mounted rod anodes and 12 large disc anodes, all designed to be diver changeable. The structure of rig creates complex shapes which cannot be fully protected with an ICCP system alone and therefore the design incorporates the use of sacrificial anodes to provide comprehensive corrosion protection.
In total 780 sacrificial anodes will be supplied to protect the port and starboard water ballast tanks, submerged cross members and seachests. Cathelco pipework anti-fouling systems, using copper and aluminium anodes, will safeguard against bio-fouling in four seachests with flow rates of 2, 280 cu. m per hour.
The first of the platforms will be delivered in 2010 and the second in 2011. They have been designed to operate in the Barents Sea and Kara Sea drilling to a depth of 7.5 kilometers in up to 500 meters of water. It is known that these areas can be threatened by icebergs of up to 4 million tons in weight, a factor which has an important influence on the design and construction of the rig.
StatoilHydro’s Technology to Make a Breakthrough
in Multiphase Metering
Multiphase measurements are important for increasing the recovery rate, taking the correct division of revenue between owners and reporting to the authorities.
StatoilHydro’s high-performance multiphase and wet gas meter is using tomography-based technology (3D Broadband™) to reduce measurement uncertainties in all multiphase and wet gas flow regimes. The 3D Broadband™ technology is used to establish three dimensional measurements of the flow inside the pipe.
The meter can perform up to two hundred complete measurements every second. For each measurement, the meter produces flow rates for all three phases (oil, gas and water) in the multiphase flow. The image is made using very fast electronics, which can analyse up to 27 different measurement planes of the pipe at hundreds of different frequencies, within a few thousandths of a second.
The meter is designed in two versions, one for topside (platforms and floating installations) and one for subsea applications.
Specification for MPM subsea multiphase and wet gas meter qualified in August 2007.
• Design pressure of 15 Kpsi (1,000 bar);
• Design temperature of -50 to +250 C;
• Water depth of up to 3,500 meters.
Lenovo’s Workstations Designed to Process Oil and Gas Exploration Data
Lenovo Company has presented workstations under the new trademark ThinkStation intended for equipping of the design departments, companies involved in digital content development, industrial companies and other areas, where complex problem solution is required; they are designed for specialists whose activity is related to the systems processing large amounts of data: work with 2D and 3D-graphics, video processing, CAD/CAM/CAE systems, oil and gas exploration systems.