Abstract
A giant oil field offshore has been developed to date using vertical and then horizontal wells drilled off-shore from wellhead platform towers. In order to reduce costs reducing the number of wells required to drain the reservoir with improving recovery, further development of the field was planned using extended-reach long horizontal wells with throws greater than 18,000 ft and measured depths greater than 25,000 ft with some wells exceeding 35,000 ft.
This paper will discuss how to reach an integrated robust completion design methodology to maximize performance of these long horizontal wells. The methodology considers a combination of two essential designs; Lower completion design and Stimulation design.
While the key objective of lower completion and stimulation designs has been to connect wells to reservoirs at their best performances with the most effective and economical way, productivity/injectivity from every foot of these long laterals as well as long term performance are the keys to successful well design and reservoir development strategy. The design methodology incorporates several constraints from reservoir such as heterogeneities in permeability, pressure and porosity, and uncertainties in those properties prediction including presence of faults/thief zones. The design methodology also incorporates the objective to be able to perform well surveillance, such as PLTs, as well as manageable installation of lower completion. The paper will give examples of application of this methodology in designing a10,000+ ft long limited-entry liner which facilitates bullhead high pressure – high rate stimulation – high acid concentration in order to place acid across the entire lateral and maximize stimulation effectiveness of every foot of the lateral. The paper will also discuss actual well performances of available long lateral wells along with lessons learned.
