Executive Summary:

The Basin Research Group at Penn State University proposes PHASE 2 of their time-lapse (4D) industry consortium. The consortium will last three years and will have an annual cost of $15,000 per company. Penn State research will focus on two core issues: 1) 4D studies that emphasize closing the loop in order to evaluate how 4D can impact exploitation decisions. This work will emphasize how reservoir characterization, seismic differencing, reservoir modeling, and acoustic modeling can be integrated to refine reservoir characterization studies and optimize exploitation programs. 2) Characterizing seismic repeatability with streamer and bottom-cable data. This work will focus on evaluating the improvement of seismic repeatability as one steps from legacy seismic data to ocean bottom cables. Three core field areas will be analyzed: 1) South Timbalier 295; 2) Teal South Field (EI 354); and 3) an unnamed (and unchosen) oil field. Benefits to industry sponsors include: 1) Twice yearly meetings (in Houston or New Orleans); 2) Free license to software and algorithms developed by Penn State; 3) Documented case studies of 4D seismic analyses in 3 oil fields.

Start Date: July 1998

Duration: 3 years

Cost: $15,000/year

Product: Repeatability analysis and integrated reservoir model and 4D analysis

Project Directors:

Peter B. Flemings, Geoscientist James P. Ashbaugh, Petroleum Engineer

Penn State Geosiences Penn State Geosiences

442 Deike Building 407 Deike Building

University Park, PA 16802 University Park, PA 16802

814-865-2309 (w) 814-863-2474 (w)

814-863-7823 (fax) 814-863-7823 (fax)

http://hydro.geosc.psu.edu http://hydro.geosc.psu.edu

Introduction:

Over the last three years, Penn State has developed considerable expertise in time-lapse seismic analysis. Our skills extend from reservoir characterization, to time-lapse differencing, to reservoir simulation. We believe that our major contributions have been two fold. First, we have participated in one of the most successful efforts to date to accomplish time-lapse seismic analysis on legacy seismic data (3D seismic data not shot for 4D analysis) in the South Timbalier 295 field. This effort included reservoir characterization, production analysis, time-lapse differencing, and reservoir modeling. Second, we have developed a methodology to quantify repeatability of seismic data by characterizing the correlation between seismic data sets, proposed a statistical model to describe the distribution of noise in these data sets, and then used this characterization to establish prediction bands that quantify the probability that a given seismic difference is real or due to noise within the seismic data sets.

Research for Time Lapse (4D) Phase II:

We now propose to extend these efforts in two manners: 1) demonstrate the utility of 4D in reservoir exploitation using an integrated work flow and 2) evaluate the cost/benefit relationship between various levels of data processing and the resulting correlation between data sets.

Time-Lapse Workflow: Demonstrating the Utility of 4D:

We will continue our efforts to integrate the work flow of time-lapse (4D) seismic analysis. Figure 1 illustrates the basic work flow pursued by Penn State over the last three years. We have been most successful in the first half of this cycle where we have stepped from reservoir characterization through reservoir modeling. What remains is to close the loop by integrating our reservoir simulation, acoustic modeling, and seismic differencing into a more refined reservoir characterization and then documenting how this characterization could be used to modify exploitation programs. The core research goal will be to understand how the integration of these tools can be used to refine our reservoir characterization and lead to better reservoir management and development drilling.

Figure 1. Combining Geologic Modeling, Reservoir Simulation, and 4-D Seismic to improve reservoir characterization

Quantifying and Characterizing Repeatability: Cost/Benefit Analysis of Different Seismic Data Sets:

We will further pursue the characterization of repeatability, and the development of algorithms to quantify that repeatability (Figure 2). Figure 2 illustrates improvement in correlation gained from post-processing of legacy seismic data over the ST295 field. The left line represents the correlation between the data sets prior to any processing, whereas the right line shows the correlation after band-pass filtering, cross-correlation, and cross-equalization. A key question that remains is how much can this correlation be further improved by reprocessing of streamer data, or by acquiring the data differently (e.g. ocean bottom cables). The core issue here is to establish the economic benefit vs. the cost of acquiring 4D seismic data.

Figure 2. Each step of normalization increases the correlation. How will correlation and repeatability improve as new processing and acquisition techniques are applied?

What is the cost/benefit of improving correlation?We will address these questions in two areas. In South Timbalier 295, swaths of 3-D seismic data will be re-processed to optimize the correlation between the seismic data sets. The improvement in correlation will be compared to the effort of re-processing to better understand the benefits of re-processing legacy seismic data for 4D analysis. Second, in South Teal (Eugene Island 354), we will characterize the repeatability of bottom-cable data and compare this repeatability to that acquired in legacy seismic data for this field.

Data Sets:

South Timbalier 295:

As part of the Lamont-Penn State 4D consortium Penn State has developed an extensive data base for the ST295 field. This includes: 3 vintages of 3D seismic data and a full well suite and production history. Penn State has approached Shell over the possibility of releasing pre-stack seismic and they are supportive of this effort. Penn State has also approached Western Geophysical and they have indicated that this could most likely be worked out.

Teal South (EI-354):

As part of the Lamont-Penn State 4D consortium, Penn State has developed an extraordinary data base in the EI-330 region. In addition, Penn State is currently negotiating to be part of a developing T4D-4CU acquisition consortium directed by HARC on TexacoUs Teal South field. Flemings has met with representatives from TexacoUs asset team for the Teal South field and with the Texaco research lab. Both are very supportive of Penn State’s effort to pursue a 4D analysis of the Teal South field.

Unknown Field:

Penn State looks forward to examining a 3rd field and looks forward to working with industry partners to determine this field.

Figure 3. Location of proposed study areas

Personnel:

Penn State has a team of professionals with expertise in reservoir characterization, geophysical processing, and reservoir simulation. In addition, we are currently recruiting graduate students to pursue this study.

Peter B. Flemings (Associate Professor, Penn State):

Peter B. Flemings will direct the consortium. He has skills in three and 4D seismic analysis and reservoir characterization.

James P. Ashbaugh (Research Associate, Penn State):

Jim Ashbaugh is a reservoir engineer with 5 years of industry experience. Jim has an extensive background in production data analysis and reservoir simulation using Eclipse.

Students

We currently have 1 M.S. student and 1 Ph.D. student working on time-lapse seismic-related research projects. These students have experience analyzing seismic data and have interests in seismic interpretation and reservoir characterization. Penn State is currently recruiting a new group of masters and doctoral geoscientists for matriculation in the fall of 1999. We have identified a minimum of 4 prospective students that are highly interested in time-lapse seismic problems.

Benefits to Companies:

Benefits to industry sponsors include: 1) twice-yearly meetings (in Houston or New Orleans); 2) free license to software and algorithms developed by Penn State; 3) documented case studies of 4D seismic analyses in 3 oil fields.

Schedule of Consortium:

Penn State would like a declaration of intent over the course of the spring and would like to have a formal commitment in July, 98. The Penn State Time Lapse (4D) Phase II consortium will last 3 years with an annual commitment of $15,000 per year. Figure 4 records Penn State’s expenditures over the last 3 years. It is a good indicator of how costs will be distributed over the next three years.

Budget & Costs:

Figure 4. Overview of monies spent to date on Time-Lapse Consortium: Phase I