Complex analysis of both drilling-induced tensile fractures and stress-induced borehole breakouts for estimating of 3-D in situ stress state

Hydraulic fracturing has been widely used as a method of measuring in-situ stresses in a borehole. It is generally assumed that one principal stress is parallel to the borehole axis and the magnitude is equivalent to the weight of overburden. Also it is sometimes hard to apply the method to a hostile environment such as geothermal. In the present paper, we describe a new method for determining the three-dimensional in-situ stress field using drilling-induced tensile fractures and stress-induced wellbore breakouts which are observed from a log such as the borehole televiewer (BHTV). We will show how we interpret the data in order to estimate the three-dimensional stress fields. Then we describe the results of interpretation at Rosemanowes well RH-15 and compare them with the results of overcoring tests conducted at South Crofty mine. The overall agreement between the proposed method and overcoring indicates the validity of the proposed method, which is applicable at a greater depth in a practical well.