Abstract
The main objective of this paper is estimating the horizontal stresses and calibration of the log-derived horizontal stress profiles in deep oil wells according to their wall failure evidences, including both compressive (breakouts) and tensile failures (drilling-induced tensile fractures). Estimation of the horizontal stress profiles using well logs is one of the standard methods in the oil industry. Another method for estimating horizontal stresses is analyzing failure evidences in the wellbore wall. By integrating these two methods, a practical strategy was followed in this research to determine the horizontal stress profiles. By this strategy, minimum and maximum horizontal stress profiles are determined in such a way that the stress concentration at the wellbore wall at the tensile fracture identified depths, exceeds the formation tensile strength, while at the breakouts identified depths it exceeds the compressive strength of the formation. An advantage of this procedure is that does not require to measure in situ stresses. Also, due to the presence of a large number of breakouts and the induced fractures detected in different zones of a deep wellbore, log-derived stress profile calibration is done using the stress state in different zones that causes to increase the accuracy and reliability of the obtained horizontal stress profile. The proposed solution was applied to determine the horizontal stress profiles in a deep oil well in the southwest of Iran as a real case.
Highlights
Orientation and magnitude of principal stresses in hydrocarbon fields in are considered as a very important information in Petroleum Engineering
The main objective of this paper is estimating the horizontal stresses and calibration of the log-derived horizontal stress profiles in deep oil wells according to their wall failure evidences, including both compressive and tensile failures
Minimum and maximum horizontal stress profiles are determined in such a way that the stress concentration at the wellbore wall at the tensile fracture identified depths, exceeds the formation tensile strength, while at the breakouts identified depths it exceeds the compressive strength of the formation
Summary
Orientation and magnitude of principal stresses in hydrocarbon fields in are considered as a very important information in Petroleum Engineering. Knowledge of the stress state is important in the petroleum industry, but it is vital in geotechnical applications and other solid earth sciences. Widespread studies have been conducted and different measurement methods and theories or empirical relationships have been established for estimating the stress state in the earth’s crust. According to Zoback et al (2003), hydraulic fracturing test, leak-off test (LOT), and measurement of pressure while drilling (PWD) are three common methods for the least principal stress measurement in the deep wells. The magnitude of minimum horizontal stress (Sh) in the normal and strike-slip faulting regimes can be measured using the mentioned methods. Measurement of the maximum horizontal stress (SH) using the mentioned methods is not directly
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