Early-Stage Field Layout Design of Subsea Production System Considering the Reservoir and Geological Uncertainties

The objective of this research is to present an early-stage field layout design of subsea production system while considering the reservoir and geological uncertainties. It incorporates two random variables: well flowrate and well target location, both associated with reservoir and geological randomness. This research employs a comprehensive simulation framework for subsea layout design, which minimizes the overall development cost while accounting several real-world factors such as seabed topography, flowline curvature and crossings, pigging requirements, manifold slots, and process host types. The effect of detailed flowline routing is also considered. A novel strategy is used to generate correlated and uncorrelated input samples for the well flowrate and well target location, respectively. The simulation framework decomposes the overall design problem into various decision problems such as well grouping, locating manifolds and process-hosts, and flowline network and its route design. An algorithmic approach is used for each decision problem. Additionally, an iterative approach is used to find the optimal flowline route configuration while considering the bathymetry, exclusion area, and laying curvature. The analysis results are summarized using statistical methods. The proposed approach is applied to the design of hydrocarbon field from Angola. This field consists of nineteen production wells. The generated random input samples for the well flowrate maintain a consistent correlation strength of 0.9 with an assumed triangular probability density function, reflecting reservoir-specific characteristics. The sample generation technique also respects the flowrate capacity constraints. For each sample, the design generates sixty-eight preliminary layouts, out of which the top designs undergo iterative flowline design to obtain the optimized flowline configuration. These designs are evaluated based on flowline length and total cost index. This is composition of drilling cost, subsea structure cost, and flowline cost. The robust designs are identified based on frequency of occurrence. The results show that the proposed method can select the robust design considering the reservoir and geological uncertainties. The novelty of the present approach is in incorporating both random and deterministic variables into the early-stage design of field layout, considering the stochastic nature of the reservoir and geological conditions. Also, modeling of the propagation of uncertainties across various subproblems while considering the detailed flowline route is novel. This approach provides subsea layout engineers with crucial insights, allowing them to evaluate unique designs while considering uncertain design variables.