Integrated asset modelling allows coupling fluid behavior in the full production system, from the reservoir to the facilities. This approach is crucial when different field development scenarios need to be evaluated during concept selection. Different situations must be systematically examined allowing for the optimal operational constraints (rate and pressure limits) and the dimensions of individual elements to be defined, whilst ensuring that material balance considerations are honoured.

Traditionally, reservoir, production and facilities groups separately conduct field modelling and simulations for each element in the system, as part of an iterative process. Reservoir engineers receive facilities constraints and lift performance curves from production engineers as an input. In return, production and facilities engineers receive production profiles from reservoir engineers and design the appropriate facilities capable of safely processing and transporting the produced fluids throughout the lifetime of the project. Any changes in production configuration affect all the models and leads to a need for each discipline to revaluate their simulation models. This process often results in approximations being adopted and frequently raises challenges in the audit trail, as assumptions may be inadequately documented.

Integrated simulation generates representative field production forecasts and the ability to quantify cumulative production and key performance indicators for each scenario. As an example, rates, erosional velocities, pressures and temperatures profiles, compressor and pump requirements and many other variables may be explicitly studied throughout the entire life of the field. This approach reduces the risk of facilities bottlenecking and flow assurance becoming an HSE issue.

This paper describes some of the integrated asset management studies conducted to evaluate different strategies for the development of an ultra-deep water exploratory block, and the key technical factors considered.

For each concept studied, multi-disciplinary models were created to simulate reservoir, tubing, flowline and surface network behaviour for gas condensate, light oil and water production streams. Subsea separation and surface process facilities options were modelled to coordinate the work streams of the different engineering domains, in a coupled solution.

Some complex development scenarios were included. A gas-reinjection case was modelled, where the separated gas from process simulation model is reinjected into the reservoir. Another scenario considered an ultra-deep subsea separation and boosting unit, which was modelled by process simulation software, connected to both the surface network and the reservoir simulation. All were linked with the FPSO process simulation. A range between 5 to 17% of oil gain was obtained in the different scenarios.

As a result of these studies, the decision making process for future investments in the field development plan was optimized.

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