In context with the low productive fields of Western Offshore where the production in the range of 500 to 1000 BOPD the field specific completion techniques in commensurate with the reservoir characteristic is a big challenge.
The main reservoir of Western Offshore is a fractured limestone reservoir with high degree of heterogeneity. In general, such reservoirs offer the best prospects for open hole completions that offer several benefits including cost effectiveness and ease of execution. But these long horizontal open hole adds major risk component to well design for such heterogeneous, water flooded carbonate reservoirs and increases the potential risk of exposing undesirable geologic portions such as water filled fracture networks, zones of high water saturation, high permeability thief zone intervals etc. and decline in production generally happens due to the sudden increase in water break-through and hole collapse attributed due to the following reason:
High degree of Resistivity difference (heterogeneity) along the horizontal open hole.
Presence of shale in some portion of the open hole section.
Water coning from heel due to high drawdown.
In some reservoir of Bassein field there are thin oil rim with a huge overlain gas cap and underlain water.
It is important to establish a cost effective completion techniques to exploits such grey fields comparing highly expensive smart wells.
A Coil Tubing Friendly Segmented Completion with open hole packer along with coil tubing operated Sliding Sleeve or without sliding sleeve / Perforated liner has been established as an economic and successful completion to mitigate the aforesaid problems. The use of uniform flow system in conjunction with open hole packer may be an appropriate and economic method for exploiting oil from thin oil rim.
This paper contains cost effective case histories of reservoir specific completions and looking for future challenges.