Advance Seismic Interpretation Project Missouri University of Science & Technology Geology & Geophysics Department Prepared & Presented by Ibrahim E Ahmed Amari & Jude Ichoku 2011

1- Introduction 2- The objectives of the project 3- Geological Setting of the study area 3.1 Regional Geology of Stratton field 3.2 Structural Framework 3.3 Stratigraphic setting 4- Data And Methods 4.1 Three-Dimentional seismic Data 4.2 Well Log Data 4.3 Interpretation Workstation 4.4 Methodology 5- Seismic Interpretation 5.1 Data Loading 5.2 Generation of Synthetic Seismograms 6 - Prospect Evaluation 7- Volumetric Calculation 8- Conclusion

1- Introduction 1- INTRODUCTION Texas,which at the northern end of the FR-4 gas play (Fig 1.1). The Stratton field is a large mature gas field located in the northwest Gulf Coast of south Texas. (Hardage el al., 1994) This study was based mainly on a set of three-dimentional seismic data and 3 well logs within area less than 2 square miles. ( Well # 1, Well # 4 & Well # 11). According to (Galloway, 1998) The Frio Vicksburg Formations are the two major gas-producing horizons in the Stratton field and other major fields of the FR-4 gas play (Figure 1.1).

2- Objectives of the project 1- Understanding the geological setting of the Stratton field of the study area. 2- Interpreted the horizons & possible prospects. 3- Importing out well logs to analysis the reservoir characterization in the middle Frio Formation. 4- Identifying prospects area within the middle Frio Formation and estimating their volumetric gas.

3. Geological Setting 3.1 Regional Geology of Stratton field The formation is a sediments-supply-dominated sequence characterized by rapid deposition and high subsidence ( Galloway el al., 1982, Morton and Galloway, 1991). The thickness of the Frio Formation ranges from less than 2,000 ft near the Vicksburg faults zone to greater than 9,000 ft towards the central part of the Rio Grande embayment (Galloway el al., 1982). 3.2 Structural Framework: The Frio Vicksburg Formations of the Stratton field are characterized by a dip-oriented seismic line crossing the Vicksburg fault zone and extending across the study area ( Al-Azhar and Marfurt, 2008). 3.3 Stratigraphic setting The Frio Formation is generally divided into lower, middle and upper section. The lower parts in the Stratton field occurs at depth between 7000 and 7400 feet. The middle Frio Formation is composed of interbeded mudstones and sandstones. It is about 200 to 2500 feet thick (Kerr and Jirik, 1990). The upper Frio Formation consists of interstratified mudstones and laterally continuous sandstones about 40-80 feet thick. ( see Figure 4.1)

4- Data And Methods 4.1 Three-Dimentional seismic Data The three-dimentional seismic data for this project are from less than 2 square miles of Stratton field in south Texas. The migrated three-dimentional data volume was a SEG-Y format and comprises 100 inlines & 200 crosslines & the bin spacing was 55ft. The minimum ([inline, crossline] = [1,1]) position was set at (x,y) (0,0), and the maximum ([inline, crossline] = [100, 200]) was set at (x,y) (10945, 5445). 4.2 Well Log Data Data from 3 wells logs were provided, as shown in Table 1,2 & 3. The log suites varies in type of logging tools used in quality of data acquired. GR, density & resistivity logs were used in this project to generate synthetic seismograms.

Well logs of Well # 11 Figure 4.1

4.3 Interpretation Workstation

4.4 Methodology See Figure 3.2

5- Seismic Interpretation 5.1 Data Loading Loading of the 3D seismic and well log data into the Kingdom Suite workstation involves a number of steps that must be carried out with care. First a new project must be created for the study area. The wells location (see Figure (5.1), seismic & well logs data can then be imported. To ensure that the data has been correctly uploaded it is necessary to display a vertical seismic section of the study area (Figure 4.2). Table 4.1 shows the list of parameters for loading the well log of well #11. Finally upload the formation tops & T-D chart to create the synthetic seismogram. Figure (4.1) shows the synthetic seismogram of well # 11.

Well logs, T-D charts, Synthetics & locations ( 1, 4 & 11) Figure 5.1

Synthetic seismogram of Well # 11 Upper Frio Formation Middle Frio Formation Lower Frio Formation Figure 4.1

5-2 Generation of Synthetic Seismograms

6- Prospect Evaluation Within the created grid map which showed a structural high “closure”, one prospect ( area A) was selected. In evaluating this prospect in terms of recoverable reserve, the following data will be needed from both well logs and seismic maps: 1-The thickness of the reservoir 2- The rock volume of the prospect ( Digitized area from grid map) 3- The porosity of the reservior. 4- The water saturation for the reservior.

7. Volumetric Calculation

Time Structure Map

Prospect Area ( Grid Map)

8. Conclusion Grid map reveal one prospect area, the study area has average porosity of 25% & average water saturation of 22%. Prospect evaluation and volumetric calcualtion indicate the reservior in-place gas reserves of 593,233.300SCF. This reservoir gas mainly located within the middle Frio Formation. The Stratton field is located in the Gulf Coast Basin of south Texas,which at the northern end of the FR-4 gas play