Well logging interpretation for a fractured igneous rock resevoir in the Wihcian Buri Subbasin, Thailand | |
| Author | Tanadech Kanjanapan |
| Call Number | AIT Thesis no.GE-16-18 |
| Subject(s) | Reservoir--Thailand--Wician Buri Subbasin Logging--Thailand--Wician Buri Subbasin |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Geotechnical and Earth Resources Engineering with Area of Specialization in Geo-System Exploration and Petroleum Geo-engineering, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis;no. GE-16-18 |
| Abstract | Igneous reservoirs have been found in various parts of the world for example in Vietnam, Venezuela, and Japan etc. In Thailand, an oil field from Wichian Buri subbasin operated by ECO energy (Thailand) has produced oil from both clastic and igneous rock reservoirs. The instrusion of magma during Oligocene-Miocene into sedimentary layer may have contributed to maturation of hydrocarbon and became another reservoir when it was fractured by tectonic force in the later time. It this study, concept of petroleum system of igneous rock reservoir was reviewed. Thin section analysis from rock cutting was conducted to understand more on the rock type of the fractured igneous reservoirs. Thin section analysis was performed for four well (denoted as X1 to X4) on cutting samples since there is no core sample available. Most of particle found in thin section image are opaque and oxidized mineral. Four of rock forming minerals were found i.e. Plagioclase (47 – 66%), Hornblende (16 – 37%), Biotite (4 – 15%), and Pyroxene (0 – 24%) that indicate an intermediate to mafic composition. Based on this composition, matrix density and travel time were calculated with the former from 2.83 – 2.97 g/cc and the latter from 49.69 – 51.25 s /ft. These values are used to calculate density and sonic porosity. The calculated porosities show good agreement with neuron porosity. Well X1 has two fractured igneous reservoirs. The first is diorite at 733.22 mTVD with thickness of 3.36 m. This zone has total porosity 0.3, shale content 0.76, water saturation 0.44, and fracture permeability 993.19 mD. The N/G ratio is 0.38 and net pay thickness becomes 1.26 m. This zone was sealed by top and bottom claystones (Wichian Buri unit 3) which also act as source rock with TOC 3.04 %wt at top and 4.22 %wt at bottome. The second reservoir is diorite intrusion at 743.38 mTVD which has total porosity of 0.36, shale volume 0.36, water saturation 0.74, and fracture permeability 7,919.48 mD. The N/G ratio is 0.52 and net pay thickness becomes 13.56 m Well X2 has an igneous reservoir as diorite intrusion located at depth 755.93 mTVD with 36.394 m thickness. The average reservoir properties are total porosity 0.29, shale content 0.52, water saturation 0.24, fracture permeability 0.11 mD. The N/G ratio is 0.79 and net pay thickness is 27.97 m. The source rock of this well is Wichian Buri unit 3 located at depth 748.86 - 755.93 mTVD with TOC 1.47 %wt. Well X3 has two igneous reservoirs as diorite intrusion. The first reservoir is at depth 675.96 mTVD and thickness about 1.5 m. This zone has total porosity 0.19, shale content 0.09, water saturation 0.17, and fracture permeability 1139.07 mD. The N/G ratio is 0.86 and netpay thickness is 1.28 m. The second reservoir is at depth 683.43 mTVD and thickness of 17.928 m. This zone has total porosity of 0.09, shale content 0.12, water saturation 0.07, and fracture porosity of 0.05. The N/G ratio is 0.97 and net pay thickness is 17.37 m. Two zones of source rock (Wichian Buri unit 3) were observed at depth 647.58 - 675.96 mTVD and 677.46 - 683.43 mTVD with TOC 2.64 and 0.35 %wt respectively. Well X4 has one igneous reservoir. This reservoir is diorite intrusion at depth 592.27 mTVD and thickness 29 m. This zone has a total porosity of 0.16, shale content of 0.21, water saturation of 0.2, and fracture permeability of 0.52 mD This zone has N/G ratio 0.99 and net pay thickness is 28.62 m. The source rock of this well is Wichian Buri unit 3 located at depth 574.87 - 592.27 mTVD and 621.27 - 667.67 mTVD with TOC 0.88 and 0.34 % wt respectively. Finally, the interpretated results were compared with stratugraphic unit in presious studies. Source rock found in each well are interpreted as Wichian Buri unit 3. Wichian Buri unit 1 is found in Well X4 only which act as clastic reservoir. Wichian Buri unit 2 were observed in well X2 and X3. This unit act as seal and shows high water saturation. A set of tables showing well log response and petrophysical properties of each stratigraphic unit is done for futher study on well correlation. |
| Year | 2017 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis;no. GE-16-18 |
| Type | Thesis |
| School | School of Engineering and Technology (SET) |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Geotechnical Engineering (GE) |
| Chairperson(s) | Pham, Huy Giao; |
| Examination Committee(s) | Noppadol Phien- wej;Chao, Kuo Chieh; |
| Scholarship Donor(s) | Royal Thai Government Fellowship; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2017 |