Liuhua 11-1 Development - Batch Drilling Program is Successful in the South China Sea
Authors: Gray George E. , Hall Kenneth H. , Mu Huang Chang 
Published: October 2008

This paper focuses primarily on the rig-of-opportunity phase of the Liuhua 11-1 Development Project, a multi-well sub sea development in the People's Republic of China. This phase was comprised of batch drilling operations for 30-in., 13 3/8-in., 9 5/8-in. and 7-in, casing intervals. The emphasis of this paper is the batch drilling operations below the 30-in. conductors. Operational details are presented by hole section. The project team achieved exceptional results during this phase due to the efficiency of batch operations, and the appropriate use of technology, teamwork, and preplanning.

Introduction

The Liuhua 11-1 Development Project is the development of an offshore oilfield located in Contract Area 29/04 of the South China Sea. It is being developed by Amoco Orient Petroleum Company (AOPC), China Offshore Oil Nanhai East Coloration, and Kerr-McGee China Petroleum Ltd., with AOPC as the operator. This field is located approximately 120 miles (200 km) southeast of Hong Kong, An overview of the development is presented in OTC 8172 (Ref. 1).

The Liuhua 11-1 Field was discovered in January 1987, and was thoroughly tested during an extended drill stem test in 1989 of the Liuhua 11-1-6. The test was of a horizontal delineation well that was drilled in 1988. The resemoir is comprised of carbonates of the Lower Miocene Zhujiang Formation. The section above the reservoir is a thick sequence of Lower Miocene to recent marine clay stones. The overall development program calls for drilling and completing 20 sub sea, horizontal wells. The rig-of opportunity phase was the initial phase of this development, and employed a contract rig to establish up the sub sea wellhead array and initiate drilling of the development wells. The sub sea wellhead army was the first eritieal step, and was the foundation for the 'building block' construction process used to create Liuhua's sub sea production system on the seabed as reviewed in OTC 8175 (Ref. 2).

On October 1, 1994, the semi-submersible drilling rig of opportunity began the tow to location from Hong Kong. The water depth at the Liuhua site is 1,020 ft (310 m). Once the rig was on location, a sequence of batch operations were performed to set twenty-five 30-in. conductors as detailed in OTC 8174 (Ref. 3). The rig drilled fifteen 13 3/8-in. surface hole sections and ten horizontal wells to TD, After running the blowout prevented (BOP), the wells were drilled to total depth (TD) by setting 9 5/8-in. casing into the top of the Zhujiang Carbonate, and setting approximately 2,500 ft of slotted 7-in. liner in the horizontal pay interval. Atl wells were temporarily abandoned awaiting future completion operations. The rig was released 154 days later on March 3, 1995. Fig. 1 reviews the complete rig-of-opportunity opemtion schedule.

Preplanning and Teamwork

Amoco brought drilling, operations, and sub sea installation personal, including contractor personnel, together early in the projeet to perform sufficient preplanning for this deepwater development.