Determination of eaton's exponent in the Gulf of Thailand | |
| Author | Prairaya Somanandana |
| Call Number | AIT Thesis no.OTM-09-04 |
| Subject(s) | Hydrostatics--Thailand, Gulf of Hydrostatic pressure--Thailand, Gulf of Thailand |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering Offshore Technology and Management, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. OTM-09-04 |
| Abstract | Eaton's model, a pore pressure prediction equation utilizing porosity to stress relation, has one of the governed factors known as Eaton's Exponent "EE", acting as enhancing factor of overpressure zones. Via his model this factor obtained empirically and suggests that it should be estimated by region due to differences in area's characteristics, leading to the study of specific EE within the Gulf of Thailand. In Eaton's model overpressure sections buried in deep portion of thick sediments with small heterogeneity. In contrast to the study areas locate in the Gulf of Thailand within Pattani Basin to Northern portion of Malay Basin, abnormal pressure zones are in much shallower portion, in heavy faulting system, with thin sequences of sand/shale interbeded, and influenced by high heat flow. In this paper, EE determination method utilizes actual formation pressure measurements under three major controlling factors of overburden stress, shale normal compaction, and temperature. Most study wells are at normal hydrostatic condition, instead of pore pressure gradient in P/Z now use calculated fluid gradient from RFT/MDT comprises with fluid sample report. The most suitable EE is calculated from fluid gradient in hydrocarbon interval. This resulted from a difficulty in estimating pressure in shale section due to shaly ambiguity and non-linear relation of formation pressure. Furthermore, by calculating using all fluid gradients instead of only hydrocarbon zone will lessen the effect of abnormal pressure. Eaton's exponent is directly affected by temperature but inverses to overburden stress. The calculated EE is estimated according to region where EE in North region (North Pattani Basin) is 0.7, then decreasing to 0.4 in Southern regions (South Pattani Basin and Uppermost portion of North Malay Basin), and then jump to approximately 1 or above in Northwestern flank Malay Basin where well locations lie in close proximity to high heat flow zone (Central Malay Basin). In water wells, EE is approaching o. Predicted pore pressure from Eaton's equation using conventional sonic Eaton's exponent in sonic technique or "3", and using calculated EE, shows 38% and 9% deviation from actual fonnation test pressure, respectively. This evidently proves that predicted EE improves accuracy in the Gulf of Thailand region. |
| Year | 2009 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. OTM-09-04 |
| Type | Thesis |
| School | School of Engineering and Technology (SET) |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Offshore Technology and Management (OTM) |
| Chairperson(s) | Chiu, Gregory L.F.;Jirawat Chewaroungroaj |
| Examination Committee(s) | Worsak Kanok-Nukulchai;Widjaja, Joko H. |
| Scholarship Donor(s) | Pearl Oil (Thailand) Limited |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2009 |