Although the synergism provided by the interaction between geology and
reservoir engineering has been quite successful, reservoir management has
generally been unsuccessful in recognizing the value of other disciplines
(e.g., geophysics, production operations, drilling, and different engineering
functions).
The prime objective of reservoir management is the economic optimization
of oil and gas recovery, which can be obtained by the following steps:
- Identify and define all individual reservoirs in a particular field and their physical properties.
- Deduce past and predict future reservoir performance.
- Minimize drilling of unnecessary wells.
- Define and modify (if necessary) wellbore and surface systems.
- Initiate operating controls at the proper time.
- Consider all pertinent economic and legal factors.
Thus, the basic purpose of reservoir management is to control operations
to obtain the maximum possible economic recovery from a reservoir based on facts,
information, and knowledge. The engineering system of concern to the petroleum
engineer as being composed of three principal subsystems:
- Creation and operation of wells.
- Surface processing of the fluids.
- Fluids and their behavior within the reservoir.
The first two subsystems depend on the third because the type of fluids
(oil, gas, and water) and their behavior in the reservoir will dictate how many
wells to drill and where, and how they should be produced and processed to
maximize profits.
The suggested reservoir management approach emphasizes interaction between various functions and their interaction with management, economics, proration, and legal groups.
The reservoir management model that involves interdisciplinary functions has provided useful results for many projects.
- When
should reservoir management start?
The ideal time to start managing a reservoir is at its discovery. However, it is never too early to start this program because early initiation of a coordinated reservoir management program not only provides a better monitoring and evaluation tool, but also costs less in the long run. Most often reservoir management is not started early enough, and the reservoir, wells, and surface systems are ignored for a long time. Many times, we consider reservoir management at the time of a tertiary recovery operation. However, it is critical and prerequisite for an economically successful tertiary recovery operation to have a good reservoir management program already in place.
What, how, and when to collect data?
To answer this question, we must follow an integrated approach of data
collection involving all functions from the beginning. Before collecting any data,
we should ask the following questions:
- Are the data necessary, and what are we going to do these data? What decisions will be made based on the results of the data collection?
- What are the benefits of these data, and how do we devise a plan to obtain the necessary data at the minimum cost ?
The reservoir management team must prepare
a coordinated reservoir evaluation program to show the need for the data
requirement, along with their costs and benefits. It must be emphasized that
early definition and evaluation of the reservoir system is a prerequisite to
good reservoir management. The team members must convince the management to
obtain necessary data to evaluate the reservoir system. In addition, the team
should participate in making operating decisions.
What kinds of questions should be asked if we want to ensure the right answer in the process of reservoir management?
- What does the answer mean ?
- Does the answer fit all the facts; why or why not ?
- Were the assumptions reasonable ?
- Are the data reliable ?
- Are additional data necessary?
- Has there been an adequate geological study ?
- Has the reservoir been adequately defined ?
Setting a reservoir management strategy requires knowledge of the reservoir , availability of technology , and knowledge of the business , political and environmental climate .Formulating a comprehensive management plan involves depletion and development strategies , data acquisition and analyses , geological and numerical model studies , production and reserves forecasts, facilities requirements, economic optimization, and management approval .
Implementing the plan requires management support , field personnel commitment , and multidisciplinary, integrated teamwork .
Success of the project depends upon careful monitoring /surveillance and thorough, ongoing evaluation of its performance. If the actual behavior of the project does not agree with the expected performance, the original plan needs to be revised , and the cycle (implementing , monitoring , and evaluating ) reactivated .
Successful reservoir management requires synergy and team efforts. It is
recognized more and more that reservoir management is not synonymous with reservoir
engineering and / or reservoir geology. Success requires multidisciplinary,
integrated team efforts. The team members must work together to ensure
development and execution of the management plan.
All development and operating decisions should be made by the reservoir
management team, which recognizes the dependence of the entire system upon the nature and behavior engineer;
in fact, a team member who considers the entire system, rather than just the
reservoir aspect, will be a more effective decision maker. It will help
tremendously if the person has a background knowledge of reservoir engineering,
geology, production and drilling engineering, well completion and performance,
and surface facilities.
Team approach to reservoir
management can be enhanced by the following:
- Facilitate communication among various engineering disciplines, geology,
and operations staff by:
- meeting periodically,
- interdisciplinary cooperation in teaching each other’s functional objectives, and
- building trust and mutual respect. Also, each member of the team should learn to be a good teacher.
- To some degree, the engineer must develop the geologist’s knowledge of
rock characteristics and depositional environment, and a geologist must cultivate
knowledge in well completion and other engineering tasks, as they relate to the
project at hand.
- Each member should subordinate their ambitions and egos to the goals of the reservoir management team.
- Each team member must maintain a high level of technical competence.
- The team members must work as a well-coordinated. Reservoir engineers should not wait on geologists to complete their work and then start the reservoir engineering work.
In summary, the synergism of the team approach can yield a “whole
greater than the sum of its parts “.
Today, it is becoming common for large reservoir studies to be integrated through a team approach. However, creating a team does not guarantee an integration that leads to success.
Team skills, team authority, team compatibility with the line management structure, and overall understanding of the reservoir management process by all team members are essential for the success of the project. Also, must reservoir management teams be being assembled only at key investment times.
One model of the team approach follows:
- Functional management nominates team members to work on project team with specific tasks in mind.
- The team reports to the production manager for this project. Also, the team selects a team leader, whose responsibility is to coordinate all activities and keep the production manager informed.
- The team members consist of representatives from geology and geophysics, various engineering functions, field operations, drilling, finance, and so forth.
- Team members prepare a reservoir management plan and define their goals and objectives by involving all functional groups. The plan is then presented to the production manager; and after receiving the manager’s feedback, appropriate changes are made. Next the plan is published and all members follow the plan.
- The team members performance evaluation is conducted by their functional heads with input from the team leader and the production manager. The performance appraisal, in addition to various dimensions of performance, includes team work as a job requirement.
- Teams are rewarded recognition /cash awards upon timely and effective completion of their tasks. These awards provide an extra motivation for team members to do well.
- As the project goals change (e.g. from primary development to secondary process), the team composition changes to include members with the required expertise .Also , this provides an opportunity to change / rotate team members with time .
- Approvals for project AEE’s (Appropriation for Expenditures) are initiated by the team members.; however, the engineering /operations supervisor and /or production manager have the final approval authority.
- Sometimes conflicting priorities for the team members develop because they essentially have two bosses (i.e., their functional heads and the team leader). These conflicts are generally resolved by constant communication among the team leader, functional heads, and the production manager.
The success of reservoir management depends upon the reliability and
proper utilization of the technology being applied concerning exploration,
drilling and completions, recovery processes, and production. Many
technological advances have been made in all of these areas.
