TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThis paper introduces an optimization method for multi-zone or multi-lateral flow control completions. This is developed around a real application, in the world first Extended Reach Multilateral well at Wytch Farm.The flow control completion is described before the theoretical framework is set out against the background of the specific Wytch Farm well. Then the optimization plan is sketched, with detailed graphical explanation of how the optimization is performed and the assumptions and analytical relationships described. Some Wytch Farm data is presented and analyzed, showing that more work is still needed to complete this important work which is attempting to fill up a gap left by the fast development in flow control hardware over the past 5 years.The key issues in optimization are discussed along with the lessons learnt. In the closing remarks the authors state that the main objective of this paper is more to push the industry to put some much needed effort in this area than to develop a reliable tool first time round.

Acoustic cementation logging tools have been run in a full-scale cement flow loop and the logs compared to a physical examination of the cement in the annulus. In the flow loop the complete cycle of cementing operations -mud and spacer circulation, and cement placement -was carried out. The flow loop included artificial formation and double string sections.Three tools were used in the flow loop: a sonic tool and two ultrasonic pulse-echo tools. The sonic tool measures the attenuation of sonic waves along the casing and is sensitive to shear coupling between casing and cement. The ultrasonic tools measure the damping of a thickness-mode resonance and the acoustic impedance. One ultrasonic tool samples every 45 degrees in azimuth; the other provides complete coverage using a rotating probe.Conditions such as channeling, good and contaminated cement, mud and water were created in the flow loop. The logs were consistent with the subsequent physical examination, within the resolution limits of each tool. Very thin annulus and highly contaminated cement posed interpretation problems. Of the tools investigated, the rotating ultrasonic tool provided the most accurate predictions of cement distribution and quality.The results illustrate the advantages and limitations of the different types of tools, and will be a useful aid in the interpretation of cementation logs.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractA brief review of Down Hole Flow Control technology shows that it is still far from mature. Efforts on characterizing DHFC valves highlight some fundamental challenges, and indicate that DHFC valves are flow control devices, not pressure control devices as chokes are. The DHFC valve requirements are then detailed, including the functionality, mechanical, and reliability requirements and other considerations, and an attempt is made to dispel some of the misconceptions. Some simple guidelines for system/valve design and selection are also presented, providing a useful tool for the user. An example is given, demonstrating the complexity of the interactions of multiple well and reservoir parameters and some of the design basics, and the use of a simple spreadsheet simulator.It is concluded that while the DHFC technology has proved itself as viable and capable of delivering huge value to the industry, there remain some serious technical challenges, which call for continued and concerted efforts. The complex requirements should be managed with a system approach not just focusing on discrete components. Analytical tools are needed for proper system design and validation in the given application environment to achieve success.

Summary This paper discusses the novel application of technology in the cementing and bond evaluation from the world-record breaking ERD (Extended Reach Drilling) wells in Wytch Farm, where horizontal liners of the order of 800m to 1300m at TvD of ca 1600m have been successfully cemented and perforated. Detailed analysis of the conditions by a multi-disciplinary team provided some practical procedures which enabled us to achieve our objectives of zonal isolation and cement bond evaluation successfully. Important aspects of zonal isolation, such as the use of spiral-blade centraisers, rotating the liner, and trials of the ECPs (External Casing Packer) are discussed in detail. Cement bond evaluation is also detailed, involving CT (Coiled Tubing) deployment and various bond logging tools, including ultrasonic tools. The CBL was found to be surprisingly reliable if used correctly. Introduction Cementing horizontal wells and evaluating the cement integrity encounter new challenges when the horizontal section of the well becomes longer and longer, i.e. in the ERD (Extended Reach Drilling) wells. How to face up to these challenges is the subject of this paper. Cementing and its integrity evaluation of the horizontal liners in several Wytch Farm ERD wells have provided us with some good lessons and experiences. These are discussed and presented with case studies. Some brief background information is provided first. Techniques used in cementing the horizontal liners are then presented in detail, followed by discussion on the cementing evaluation including CT (Coiled Tubing) operations, logging tool selection and centralisation, and log interpretation. Case studies are then presented before the conclusions. Background Wytch Farm is the largest onshore oil field in Western Europe, and is situated on the southern coast of England, about 100 miles south-west of London. The discovery and development history of this field is briefed in paper SPE 28558. Briefly, a second reservoir (the Sherwood Triassic sandstone) was discovered in 1978 at the time the Bridport Jurassic sandstone reservoir was being developed. The Sherwood reservoir formations, at ca. 1600 m TVD, extend offshore into Poole bay, up to ca. 9 km from the existing onshore drilling sites.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractA brief review of Down Hole Flow Control technology shows that it is still far from mature. Efforts on characterizing DHFC valves highlight some fundamental challenges, and indicate that DHFC valves are flow control devices, not pressure control devices as chokes are. The DHFC valve requirements are then detailed, including the functionality, mechanical, and reliability requirements and other considerations, and an attempt is made to dispel some of the misconceptions. Some simple guidelines for system/valve design and selection are also presented, providing a useful tool for the user. An example is given, demonstrating the complexity of the interactions of multiple well and reservoir parameters and some of the design basics, and the use of a simple spreadsheet simulator.It is concluded that while the DHFC technology has proved itself as viable and capable of delivering huge value to the industry, there remain some serious technical challenges, which call for continued and concerted efforts. The complex requirements should be managed with a system approach not just focusing on discrete components. Analytical tools are needed for proper system design and validation in the given application environment to achieve success.