(164d) Effect of Availability on Multi-Period Planning of Oil and Gas Production Systems

Natural gas and petroleum are non-renewable and scarce energy sources. Although, it is well known that hydrocarbon reserves are depleting through the years, oil and gas remain the principal source of energy upon which our society is strongly dependent. Hence, the optimization and accurate planning of hydrocarbon production are the main keys to making it safer, more efficient, and cheaper. One of the tools commonly used to evaluate the optimization of oil/gas production system is the process simulation modeling.

A hydrocarbon production system typically consists of at least one underground reservoir where several wells have been drilled into the hydrocarbon-bearing rock to conform a fixed topology network. Wells are interconnected with manifolds to transport the gas or oil to a storage or sale location. The process simulation consists of calculating the total hydrocarbon production for the given production system. The pressure in the wellbore is the main variable to determine in the process. When oil/gas is produced, this pressure decreases until the production cannot be sustained. Then, the production decreases until the wells stops producing. If the well is shut down, the pressure at the wellbore increases because of the natural gas flow coming from the reservoir. In addition, artificial lift techniques, such as water injection, gas lift and pump systems can be incorporated into the simulation program. The oil/gas production has been also modeled as a multi-period optimization case to incorporate the possibility of different demands, cost and overall time behavior. The current field optimization approaches do not take into account the availability of the equipment, adding to the planning a lot of uncertainty.

In this work, we have integrated the availability analysis to the above model description. The availability of a system is analyzed by Monte Carlo simulation, which involves the modeling of the probabilities of failure, the type of failure, the time to repair associated with each failure, and time of occurrence for a field system. As a result, a new production planning is accomplished in the effective work period. It is known that availability is the ability of an item to perform its required function over a stated period of time. Thus, an accurate measure of the availability will reduce the uncertainty on a multi-period planning production of either oil or gas. Furthermore, this efficient approach will have beneficial use in financial risk decisions.