During 94-95, INTEC Engineering had been developing technology for and providing project support to the design of a deep water pipeline, to be laid from Oman to India. Water depth was 3500 m over a major portion of the distance of 1100 km. Neither equipment nor experience was readily available to build such a line, and therefore an extensive engineering exercise was undertaken to establish feasibility and to be prepared for all potential hazards of construction. In October 1995, the project was shelved for several reasons, but not for lack of feasibility. A number of papers on the survey and the technology development was published, among others at the 95 and 96 OTC.

The Russian gas transportation company Gazprom had been proposing natural gas supply to Turkey and in the review of potential pipeline routes, crossing the Black Sea by a straight line from Djubga (Russia) to Samsun (Turkey) seemed attractive. Petergaz BV, the engineering joint venture between Gazprom and Heerema Oil and Gas Development Company, was given the task to investigate the feasibility of such a route. It was clear from the start, that feasibility was not a foregone conclusion. The water depth of 2150 m would be a new world record, and the composition of the seawater (sufficient H2S to be considered sour) was unusual. Reasonable doubt existed with regard to the stability of the seabed in parts of the proposed route. In addition to these technological difficulties, the time scheme was challenging : a fast track project was required aiming at first gas delivery before the end of the year 2000.

When the telephone rang, INTEC Engineering BV was yet small, but firmly established in The Netherlands, and had access to the experience collected with the Oman-India pipeline design project. Therefore the subsequent discussions and negotiations quickly led to an agreement between Petergaz and INTEC to jointly tackle the feasibility questions. In January 97 a small team started at the Petergaz office in Leiden, soon followed by a reconnaissance survey in the Black Sea. Results were generally positive, so that in summer 1997 a next phase of the project was started : the engineering necessary to secure manageable contracts for the procurement, installation and certification of the submarine pipelines. To this end, INTEC and Petergaz formed a cooperative partnership to perform detailed engineering, detailed route survey and technology development as required. The cooperation is still in full swing at the present time, while the "manageable contract" goal is now within close reach.

The results of the feasibility study included a specification of the pipeline dimensions. Ultimately as many as three parallel pipelines may be needed. Initially only one pipe will be laid, with an outside diameter of 24" and a length of nearly 400 km. At an inlet pressure of 25 MPa, this pipe can transport over 8 billion standard cubic metres of gas per annum. Design pressure rating of the pipe is 35 Mpa at the inlet. For withstanding the external pressure during laying and the internal pressure in operation, the pipe wall thickness is 32 mm. The material grade selected is X65, which is a fair compromise between a high grade for strength and a lower grade for corrosion resistance. Even so, only few mills in the world can produce this pipe, which has to be fabricated by the UOE process.

In this Blue Stream project, challenges are plentiful. The initial reconnaissance survey came up with promising results for determining a route, but also unveiled a number of hazards. The abyssal plain was relatively flat and featureless. The continental slope at the Russian side contained gradients of 18 degrees. Free spanning in this area might be a governing design factor. The slope at the Turkish coast had indications of sediment transport and slumping. The shallow seabed along the coast was soft and silty clay with low pressure gas pockets. The currently ongoing detailed survey is collecting extensive information on physical and geo-technical properties, and refining the route definition. More unusual than these concerns are the potential problems with the H2S content of the deep sea. Performance of typical line pipe material, corrosion coating and cathodic protection in such environment was unknown. Some of the world's greatest experts on corrosion protection joined the team temporarily to help define the best direction and the tests needed to select materials. Such tests include laboratory experiments and on site deployment of test frames.

Against this development activity, the laying method might seem a matter of routine. Nevertheless, the two basic options (J lay and S lay) have been carried along in cooperation with pre-selected potential contractors until mid 1998, when the issue of a letter of intent to Saipem finally concluded in favour of J lay. The S-7000 will be equipped with a J lay tower before mobilization to the Black Sea.

The current project team of some 35 people, most of them INTEC staff, is working hard to solve the engineering problems and to perform the research needed to establish confidence in the preliminarily chosen methods and materials. Like in every real world project, the pinch of time and budget constraints is clearly felt. An important milestone is to be reached early November 1998, when the letter of intent for laying needs to result in a contract. For INTEC, the major milestone had been passed two years earlier, when Petergaz placed their confidence in our company to help them develop this unprecedented project.

The MLNG-Tiga pipeline system is designed to transport a two-phase mixture of gas and condensate from the Jintan and Helang Production Platforms to the intermediate E11R-C Riser Platform. The commingled gas and condensate is then piped via two trunklines to an onshore slugcatcher, from where the gas is transported to the proposed MLNG-Tiga Plant in Bintulu, Sarawak (East Malaysia).

The total length of the offshore pipeline system is 485 km, consisting of 148 km of 36-inch pipe, 99 km of 22-inch pipe and two 32-inch trunklines each 119 km in length. The internally-coated, Grade X-65 pipelines are designed for sour service conditions, with a design pressure of 123 bara. The maximum water depth is about 128 metres at the Jintan Production Platform.

INTEC was responsible for the detailed design of the pipeline system extending from the riser hanger flanges on the platforms (with the exception of the Jintan riser) to the onshore tie-in points at the slugcatcher facility. This included the design of two subsea tie-ins and associated protective frames on the 36-inch pipeline, for the future tie-in of proposed field developments.

In addition to the route selection, hydraulic analysis and mechanical design of the pipeline system, INTEC's scope of work included the preparation and design of:

• the offshore and onshore cathodic protection systems;
  
• the internal corrosion management program;
  
• the pre-commissioning and commissioning philosophies;
  
• the operating and pigging manual;
  
• the pipeline materials, fittings and installation specifications.
  

Tuah Mohd Alip	Roslinda Abd. Aziz
Steven Berg	Gustavo Cavallo
Andrew Easton	Richard Hempsall
Graham Parker	Todd Phillips
Reveriano Rivera, Jr	NG Yew Seng
Naomi Stein	Christopher Tam
Vincent Vetter

The following employees were recently promoted to new positions. We appreciate their hard work and congratulate them on their success:

Barbara Castellese - Accounting Supervisor
Paul Kronfield - Business Development Coordinator
Indu Mahendran - General Manager S.E.A.
Basim Mekha - Project Engineer/Engineering Specialist
Gene Mullee - Executive Engineer
Graham Openshaw - Operations Manager
David Sumner - Project Manager

ISOPE

• "Link Beam Model for Dynamic Buckle Propagation in Pipelines," - Andre Nogueira
  
• "Effect of Ramp Duration on Response of Spars to Irregular Waves" - Basim Mekha with J.M. Roesset of the Offshore Technology Research Center
  

• "Statistical Response of Spar Platforms to Irregular Waves" - Basim Mekha with J.M.Roesset of the Offshore Technology Research Center

For Texaco Group, Inc.., FPS/FPSO Historical Record Study

For Aker Maritime (Exxon), Concepts for Subsea and Pipeline Systems for Exxon in Angola

For Mariner Energy, Inc., Ewing Banks 966 Flow Assurance Study

For Christiani and Nielsen, TARP - Berth 3 Modification Conceptual Design

For Texaco, Study to Identify, Develop and Select Best Option to Support Gas Liquids Process Plant Offshore West Africa

For Stork Contractors & Engineers, Assistance for the Shell Shri Lanka Terminal Project

For Aker Maritime (Exxon), Concepts for Subsea and Pipeline Systems for Exxon in Brazil

For Texaco Group, Inc., Gorgon Trunkline Study

For Christiani and Nielsen, TARP - Berth 3 Modification Detailed Design

For Saga Petroleum UK Ltd., Feasibility Study for Corrib Field Tie-back

For British Gas International, Assistance in Tendering for the West Delta Deep Scenario Studies

For Esso Production Malaysia, Inc., EPMI, Tapis-E Pipeline Project Offshore Support for Span Support Installation

For Texaco Group, Inc., Coordination of Texaco ISTT Workshop

For Shell Deepwater, QA/QC of Umbilicals