The Maleo Producer is a converted Bethlehem JU250 mat-supported jack-up unit, which was installed in July 2006, on a soft, normally consolidated clay foundation some 40 km (25 mi) south east of Madura Island and approximately 25 km (16 mi) south of Puteran Island, offshore Indonesia. The unit was connected to a wellhead platform, and gas production began in late 2006. An initial site investigation performed in 2003 indicated that the undisturbed soil conditions consisted of a soft normally consolidated clay profile, with an undrained shear strength of 2 kPa (40 psf) at the mudline, linearly increasing with depth at a rate of 1.22 kPa/m (7.83 psf/ft) down to a depth of around 14 m (46 ft), below which a slightly stronger clay was encountered. The issue of on-bottom stability of the unit and its resistance to overturning were questioned by the classification society (ABS) as part of the reclassification of the rig. The behavior of the foundation under extreme storm loads and seismic events could be more reliably predicted by the designer, and more readily accepted by ABS, if new soil data were available. Two types of soil data were required 1) soil data for foundation design and re-analysis under and around the mat and 2) soil data for seismic analysis of the installation. This paper describes the extensive site characterization undertaken to prove the stability of the Maleo Producer facility during both the design storm and seismic events.
The Maleo Field is located in Indonesian waters about 40 km (25 mi) south east of Madura Island and approximately 25 km (16 mi) south of Puteran Island (Figure 1), within the Madura Offshore Production Sharing Contract (PSC) area.
The Maleo Producer is a converted Bethlehem JU250 mat-supported jack-up unit (formerly the CD10) ABS Class Number 7900120. The unit was installed in July 2006, and was connected to a wellhead platform. Gas production began in late 2006 (Figure 2).
The installation is in approximately 57-m (187-feet) water depth. The hull is supported on three cylindrical steel legs, 3.66-m (12-ft) in outer diameter. The legs are supported on an "A" shaped mat (Figure 3) that rests on the seafloor. The mat is 64 m (210 ft) long, 52 m (170 ft) wide and 3-m (10-ft) thick. It has 0.6-m (2-ft) deep skirts (extensions of the mat side walls) that extend along all edges of the mat (around the outside mat edges, inside the slot at the aft end and around the inside edges of the 18 m × 33m (59 ft × 108 ft) cut-out within the three legs beneath the hull (Figure 3).
A 14-in (366-mm)-diameter gas export seafloor pipeline connects the installation (from the starboard side of the mat) to the 26-in. (660-mm) East Java seabed pipeline approximately 7 km (4.3 mi) to the south.
Details of the structure's geometry, preload history, and design load conditions were provided by Stewart Technology Associates (2006 a&b), as documented in Ooley and Stewart (2008).
