Field Development Plans Optimization by Modeling Fluids Flow Impact and Assessing Intelligent Wells on Reservoir Performance

Abstract

The understanding and accuracy of modeling fluid flow behavior in naturally fractured carbonate reservoir is critical in predicting reservoir sweep efficiency, remaining drilling targets and evaluating field development alternatives. The use of appropriate complex wells design such as Horizontals, (H) Multi-laterals (ML) and completion technology such as equalizers (ICD) or Inflow Control Valves (ICV) are of equal importance. The approach presented in this paper is based on detailed integrated analysis of all available well data including logs, production, pressure transient analysis (PTA), fracture distributions, well flow profiles (PLT) etc, to provide a first-line insight of the fractured reservoir fluid flow mechanism. These first-line insights provide the basis to develop mechanistic or concept reservoir simulation models to fine-tune fluid movement understanding in fractures, reservoir matrix, well types (H, ML) and completion placement to field development strategies. Sector modeling provides further insight to well design in field areas of different rock quality and fracture density. Well type and completion strategy alternatives for each identified field area including intelligent smart well completions are developed and tested in each sector model. The combined developed understanding of fluid flow mechanisms, well type and completion strategy are rolled up and implemented into a full field simulation model, fine tuned through history match and prediction processes. This paper describes the methodology used to study a number of naturally fractured carbonate reservoirs through the integrated "Event Solution"1 study approach. The methodology presented in this paper was applied on a number of large Middle East carbonate fields. The fields studied have naturally fractured reservoirs with two distinct fracture systems. Namely, fracture corridors or clusters and diffuse or layer-bounded fractures. Diffuse fractures are typically horizontal (layer-bounded fractures) inter-connect with the fracture corridors which are normally vertical to sub-vertical. This fracture system combination forms a highly conductive fluid flow and pressure medium which is responsible for observed water movement as well as pressure propagation from the aquifer/injectors into the reservoirs. Background Literature presented some methodologies to numerically simulate fracture corridors and diffuse fractures systems in naturally fractured carbonate reservoirs. Halilu et al.2 presented a method for large fields dominated by clusters of sub-vertical fractures called fracture corridors. In this study, the effective Warren-Root and fracture parameters were adjusted to mimic explicit fracture modeling to represent fractures corridors. The study results showed that fluid flow in these fields is largely influenced by large scale fracture corridors. These large scale fracture corridors were lately named fracture fairways.

Overview of Saudi Aramco's Intelligent Field Program

“…In contrast, the bottom-up approach, uses simulation runs to brute-force explore the solution space. Each decision type (strategy, tactic, operations) is run against each subsurface uncertainty parameter (including combinations of parameters) (Elrafie et al 2008b).…”

Mechanical insights into the development of fracture corridors in layered rocks

“…Fracture corridors are believed to have a considerable practical impact on production in fractured reservoirs, by forming drains for fluids or providing permeability enhancement and/or anisotropy (Fig. 2a; Cosentino et al, 2001;Bockel-Rebelle et al, 2004Elrafie et al, 2008;Caetano et al, 2014). Drilling experience reveals their link to localized enhanced production (Hart et al, 2002), water breakthrough (local intrusion of water), and major drilling mud losses.…”