Application of rock physics in characterization of a gas hydrate reservoir | |
| Author | Pham Hong Trang |
| Call Number | AIT Thesis no.GE-18-19 |
| Subject(s) | Natural gas|xHydrates Rock mechanics |
| 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 Geosystem Exploration and Petroleum Geoengineering |
| Publisher | Asian Institute of Technology |
| Abstract | In this study, two study sites, i.e., site 01 (UBGH-2-10), site 02 (C0002) were selected for estimating gas hydrate saturation, and GH characterization, taking into account the effect of gas hydrate morphology based on the available public and published well log data. Well log analysis was performed to select the gas hydrate zone. At site 01 (UBGH-2-10) gas hydrate bearing sediment was found within 4m thick from 130 to 134 mbsf, which has GR of 45 API, RHOB of 1.4 g/cc, LLD of 9 ohm.m, and Vp from 1,623 to 2050 m/s. Gas hydrate zone is characterized by Vsh of 8%, high porosity of 75%. At site 02 (C0002), gas hydrate zone was detected from 218 to 400 mbsf, which has GR=50-100 API, RHOB=1.3-1.9, LLD=1.5-3.0 ohm.m, and Vp=1,800-2,100 m/s. GHBZ is underlain by Vsh of 44%, porosity of 55%. Gas hydrate saturation is estimated by using different methods: Archie’s equation, rock physic modelling. Gas hydrate saturation computed by Archie’s method (60%) is higher than that computed by rock physics modelling (35%) at site 01. By contrast, gas hydrate saturation predicted by Archie’s approach (15.5%) is lower than that predicted by rock physics modelling (18%) at site 02. The results of rock physic modelling application found that gas hydrate at site 01 is modeled by simplified three phase equation (STPE), and which predict GH acts as a part of fluid and a part of matrix with gas hydrate saturation of 52% on maximum at 133 mbsf, and average of 35.14%. Matrix-supporting model is used to predict hydrate morphology at C0002, considering as load-bearing type, which has a good agreement with the core measurement. The average concentration of gas hydrate is about 17.4%. For GH characterization, shear wave velocity were predicted to construct RPT by using various relations. The best performed model to predict shear wave velocity at UBGH-2-10 is STPE, while Greenberg Castagna (1992)’s empirical relation is the most suitable model to predict S-wave velocity at the site 02, matching well with the GH morphology taken from core measurement. Based on the results of RPT, gas hydrate bearing zone at site 01 has Vp/Vs = 4.5-5.5 and PI = 2,500-2,700 m/s * g/cc, while at site 02 Vp/Vs= 2.6 to 3.6 and PI = 2,500 to 4,300 m/s * g/cc. Water bearing zone at site 01 is characterized by Vp/Vs= 6 to 6.8 and PI = 2,200 to 2,400 m/s * g/cc, while at site 02, Vp/Vs = 3.2-7 and PI= 1,700 – 2,700 m/s * g/cc. |
| Year | 2019 |
| 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) | Chao, Kuo-Chieh;Noppadol Phien-wej; |
| Scholarship Donor(s) | AITCV Anniversary Scholarship; |
| Degree | Thesis (M. Eng.) - Asian Institute of Technology, 2019 |