Openhole horizontal oil producer well successfully recompleted with AZIP Packers combined with active ICDs in Libya.
The packers were successfully expanded and set with 5,000 psi. The workover was effective and allowed recompleting the well with ICDs and Xpandable AZIPs. The client benefitted from effective means of shutting off watered out zones, reducing water inflow and getting control of the well production.
Zelten field mature wells characteristics
With known reserves of 43.1 billion barrels of oil equivalent (36.7 billion barrels of oil, 37.7 trillion cubic feet of gas, 0.1 billion barrels of natural gas liquids), the Sirte (Sirt) Basin province ranks 13th among the world’s petroleum provinces.
Ageing horizontal wells from the Zelten field tend to face excessive water breakthrough. The client experienced a similar case in one of his open hole porosity producer wells. Production tests showed a severely reduced oil rate of 210 barrels of oil per day (BOPD), and they noticed an increase in the water cut from 50 to 80% on natural flow. Zelten field as any other carbonates reservoirs are facing similar challenges:
- Permeability variation along the wellbores
- Multi-fractures and/or tight reservoirs
- High water mobility rates
The above reservoir challenges typically lead to the following risks;
- Unbalanced production profile
- Early water breakthrough
- Internal cross-flow and under-production
- Un-swept regions with oil bypassed
The client well performance charts showed Water Cut (WC) increased up to 75% with oil production declined from to 348 BOPD over one year well life.
Completion Design Philosophy and Objectives
The philosophy of the proposed new generation of Inflow Control Devices (ICD) completion designs, is to incorporate Schlumberger lessons learned and best practices of ICD technology, resulting in systems that are efficient to deploy, that address reservoir challenges and allow intervention where necessary to reduce water cut.
This proposed completion design also allowed the client to improve reservoir sweep efficiency, optimize oil production and increase recovery factor.
Preference has been given to field proven equipment and technologies, the Schlumberger design approach and associated technologies leverage confidence gained through the use of proven technology. There were no solution gaps or engineering/qualification requirements necessary to meet the client’s challenges.
Therefore our completion design objectives could be summarized as follows:
- balanced inflow profile along entire horizontal section
- improve sweep efficiency
- maximize oil recovery
- decrease rate of high-mobility fluids
- delay early water breakthrough
- Isolate “shut-off” watered out zones
Active ICDs combined with openhole packers for a drastic water cut resorption
Schlumberger recommended a workover to recomplete the well with active in-flow control devices (ICD) and open hole packers, to reduce drastically the water cut, and take control of the production. The following recompletion string was recommended:
- 5in x 7in Liner hanger with Liner top packer
- 5 Saltel Xpandable AZIP-W 4.5in
- 12 Premium Port ICDs
Successful Open Hole Packers installation
Associating Xpandable Steel well Packers with active inflow control devices was a worldwide first materialized and field-proven effective in the Sirte Basin in Libya.