Page 37: of Offshore Engineer Magazine (Jun/Jul 2013)

36 38

Subsea

Umbilicals bring new production to China’s Liuhua feld

The larger project extended LH back into service and reconnected. It

After a major storm crippled 11-1’s working life by 15 years and ex- was then that Liuhua 4-1 feld could production from Liuhua panded the capacity of the FPS Nanhai be brought into production through a feld, a major life extension

Tiaozhan and FPSO Nanhi Shengli to tieback to the Liuhua 11-1 FPS. handle new production from devel- LH 4-1 feld is about 11km northwest project and new umbilicals opment of the LH 4-1 feld. LH 4-1 of LH 11-1 in 260-300m water depth from JDR Cable systems produces to the LH 11-1 FPS through and about 215km from Hong Kong. The renewed an aging property; an 11km, 18in.-diameter pipeline. feld was discovered in 1987, but could not be developed due to technical

Victor Schmidt explains.

limitations at the time. The feld is an

Background ecently, JDR Cable Systems The LH 11-1 development is in the eight-well development; seven hori- deployed several subsea produc- South China Sea is 200km southeast of zontal wells produce from a reservoir

R tion umbilicals and power cables for Hong Kong and produces heavy crude at 1622m below mudline, and one well electrical submersible pumps (ESP) from 25 wells in 310m water depth. produces from two zones at 900m and in a South China Sea, subsea-tieback The main reservoir is 914m below 1465m. Future expansion can accom- project for China National Offshore Oil mudline. The feld began producing in modate four additional wells, which,

Corporation (CNOOC). The project was 1996 and was initially designed for a when drilled and completed, will pro- part of a much larger feld-life exten- feld life of 10 years. duce through a separate manifold. sion effort by CNOOC for the Liuhua The FPS Nanhai Tiaozhan semisub- The feld is controlled by a compos- 11-1 development (LH 11-1), which mersible provides power to downhole ite electro-hydraulic system tied-back included the tieback and start-up of the ESPs and engineers onboard control to the FPS, from which control signals

Liuhua 4-1 oil feld (LH 4-1). the subsea equipment and production regulate hydraulic power and chemical rate of the feld. The heavy API-gravity injections. Each well has dual ESPs for crude is moved by the ESPs to the redundancy; production can continue

Umbilicals were loaded onto a single

FPSO Nanhi Shengli through two if an ESP fails. This capability delays carousel, similar to this operation on a 13.5in.-diameter production pipelines. the expense of a semisubmersible in- Source: JDR Cable Systems.

different project.

Liuhua11-1 feld was developed and tervention to replace failed equipment. produced until 2006, when a major Production is pumped 11km through tropical cyclone, Chanchu, broke three an 18in.-diameter pipeline to the main fexible risers and six of the ten moor- LH 11-1 manifold, where the crudes ing lines. After a riser repair and recov- are comingled and sent to the FPSO ery project, and drydock for life exten- through the two existing pipelines.

sion, the FPSO Nanhi Shengli was put This arrangement requires variable frequency power to individually control each ESP and bal- ance output among the wells. The FPS was also upgraded as part of the life exten- sion project to pro- JDR’s Hartlepool, UK facility was chosen for the LH 4-1 umbilicals, so that all could be manufactured concurrently.

Source: JDR Cable Systems.

oedigital.com June 2013 | OE 39 039OE_0613_Subsea-Umbil.indd 39 5/27/13 4:01 PM