Reservoir Management Workflow for Optimizing CO2 Injection to

Enhance Oil Recovery in Mature Oil Fields:

A Preliminary Study for a Field Pilot ProgramZachary P. Alcorn University of Bergen

zachary.alcorn@uib.no

A multidisciplinary reservoir management workflow is proposed to improve oil recovery in mature

oil fields. The workflow involves integration of traditional reservoir management methods with a

real-time optimization approach.

ReferencesAlcorn, Z.P., Fernø, M.A., and Graue, A. 2016. Workflow for Optimal Injection of CO2 to Enhance Oil Recovery in Mature Oil Fields: A Preliminary

Study for a Field Pilot Program. Presented at the SPE Bergen One Day Seminar, Bergen, Norway, 20 April 2016. SPE-180029

AcknowledgementsThe authors acknowledge the Norwegian Research Council CLIMIT program and NorTex Petroleum Cluster for financial support. We also

acknowledge Shyam Panjwani and Michael Nikolaou, both at the University of Houston, for their valuable input.

Workflow

Optimization Strategy

Robust closed loop reservoir management and optimization allows real time data

acquisition through the integration of history matched reservoir models with

mathematical models to determine operational decision making for the life of the

reservoir.

Abstract

This study proposes an integrated reservoir management workflow to

improve oil recovery in mature oil fields. The early phase field pilot research

program management strategy is composed of several key components,

including: improved reservoir characterization, generation of reservoir and

simulation models, history matched simulation models, and development of a

real time approach to optimize enhanced oil recovery reservoir

performance. An improved reservoir characterization provides the framework

for the generation of geologic and reservoir simulation models. The optimization

strategy allows decision making at two different time scales, both aiming to

optimize net present value. Several realizations of a reservoir model were

history-matched to field performance and subsequently used to predict and

optimize future performance. Assimilation of newly obtained data removes the

cumbersome task of manually updating reservoir models to forecast operations.

Reservoir ModelingCorrelation of flow zones through construction of cross sections results in a

stratigraphically layered reservoir with distinct variations in horizontal and vertical

permeability. Four flow zones are identified which correspond to laterally continuous

subtidal deposits and provide the framework for the simulation model grid. Shaley

mudstone layers limit vertical communication throughout the reservoir and are

modeled as barriers to flow.

Conclusions

1. An improved reservoir characterization further defines the complex architecture of

the San Andres reservoir.

2. A ten year history match validates the simulation models and permits their use

within the real time reservoir management approach.

3. The implementation of a real time strategy allows operational decision making to

be better informed and updated in real time.

4. Comparison of simulation model prediction cases to current field CO2 EOR

operations demonstrate the favorable reservoir response to CO2 injection and

establish the reservoir as a good candidate for CO2 foam for EOR.

5. Utilization of data-driven proxy models, trained from production-injection data,

allow this strategy to be easily applied for other oil recovery methods.

6. Application of the reservoir management plan provides essential information for

the ongoing field pilot research program.

Well log correlation

Idealized lithologic column

Static geologic model10 years of observed and simulated production data

• Identify reservoir zones

• Petrophysical properties

• Idealized model

• Generate horizons

• Stratigraphic layering

• Kv/kh

• Base static model

Problem Statement

Enhanced oil recovery (EOR) from mature oil fields presents unique challenges,

as it requires well designed workflows for the injection of water, gas, or

chemicals. Determining the optimal injection and production plan for more

developed fields can both maximize hydrocarbon recovery and reduce cost.

The proposed workflow is being adopted within a current field pilot research

program. Implementation of such a reservoir management plan allows

operational decision making to be better informed and updated in real time.

Field Pilot ProgramThe objective of the field pilot research program is to establish CO2 foam

mobility control for EOR by conducting onshore field pilots in the United States.

The program is an international collaboration with 13 universities and research

institutions and 10 oil and service companies.