Degree

Doctor of Philosophy (PhD)

Department

Petroleum Engineering

Document Type

Dissertation

Abstract

Excessive water production problem is more troubling in naturally fractured reservoirs (NFR) than matrix-only deposits. In NFR, fluid flow through fracture conduits substantially differs from that in the rock matrix. Development of fractured hydrocarbon reservoirs require good understanding of fluid flow in the network of fractures. In NFR with bottom-water drive, mitigation of excessive water is always a challenge.

This dissertation presents an experimental and numerical study of dynamic water control in fractured basements using downhole water sink (DWS) well technology. A DWS well is a dual-completed well with the top completion used for oil production from payzone and a bottom completion designated for water drainage below oil-water contact (OWC).

The experimental study investigates the effect of production rate and fracture inclination on water coning and its controlling mechanism using the DWS. Physical models are designed and fabricated with embedded fracture grooves in a bench-top Hele-Shaw cell. Physical models were built to represent fluid flow and exchange between fractures and matrix similar to a field-case NFR. The results show that at optimum operation conditions, DWS deployment resulted in successful coning control and incremental oil increase by 69-percent. The experimental study is supported by two simulation studies.

The first parametric simulation study applied in a dual-porosity dual permeability (DPDP) sector model to study the effect of fracture conductivity and spacing on water invasion and its controlling likelihood. This study assessed the severity of water coning and feasibility of DWS technique in vertical wells for water coning control. It confirms that bottom water invasion in NFR systems with highly conductive fractures are very challenging to be controlled with DWS. Nevertheless, the parametric sector model study reveals substantial water-cut reduction (by 80-percent) and six months of water breakthrough delay.

The second field-case reservoir simulation study evaluated potential advantage of in-situ water drainage for water cresting control in horizontal wells using Bi-lateral Water Sink (BWS) well variant. The study shows up to 40-percent reduction of water production from the two candidate wells. An economic evaluation of the BWS technology in this oilfield estimates that BWS investment could return 60.6 million USD in 10 years.

Date

3-18-2019

Committee Chair

Wojtanowicz, Andrew

Available for download on Monday, March 16, 2026

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