Impact of elliptical boreholes on in situ stress estimation from leak-off test data

Abstract

We developed an inversion technique to determine in situ stresses for elliptical boreholes of arbitrary trajectory. In this approach, borehole geometry, drilling-induced fracture information, and other available leak-off test data were used to construct a mathematical model, which was in turn applied to finding the inverse of an overdetermined system of equations. The method has been demonstrated by a case study in the Appalachian Basin, USA. The calculated horizontal stresses are in reasonable agreement with the reported regional stress study of the area, although there are no field measurement data of the studied well for direct calibration. The results also indicate that 2% of axis difference in the elliptical borehole geometry can cause a 5% difference in minimum horizontal stress calculation and a 10% difference in maximum horizontal stress calculation.

Distribution and controls of petroliferous plays in subtle traps within a Paleogene lacustrine sequence stratigraphic framework, Dongying Depression, Bohai Bay Basin, Eastern China

“…It is one of the most petroliferous depressions in the Bohai Bay Basin. Episodic extensional tectonic events and their associated extensional structures and depositional fills have resulted in multiple source rocks (Li et al 2003;Han et al 2018), combinations of reservoirs and cap rocks, and hydrocarbon reservoirs in structural and subtle traps (Li and Pang 2004). High density of exploration wells has provided a good chance to study the distribution and controls of the hydrocarbon reservoirs in subtle traps and to examine the conditions of hydrocarbon migration and accumulation in subtle traps in rift basins within the sequence stratigraphic framework.…”

Effect of Eccentricity on Breakout Propagation around Noncircular Boreholes

“…Using an inverse analysis, Han et al [40] estimated the horizontal in situ stresses around the elliptical borehole using data from the leak-of test, and their studies showed that even a 2% diference in the axis of the elliptical borehole causes a 5% to 10% diference in the estimation of horizontal in situ stresses. Papamichos et al [41] investigated hollow cylinders with diferent geometries experimentally and numerically, and their studies showed that holes with elliptical breakouts are more stable; in other words, the stability of the hole increases as the breakout depth increases.…”

Geomechanical Modeling and Inversion Analysis of the in-situ Stress Field in Deep Marine Shale Formations: A Case Study of the Longmaxi Formation, Dingshan Area, China

“…After nearly a century of development, the reservoir stress state can be determined by various means. At present, the research techniques for determining in-situ stress of oil and gas reservoirs and mines are mainly divided into five categories (Ljunggren et al, 2003): 1) well trajectory analysis methods (Zhao et al, 2015), 2) core test methods (Nian et al, 2016), 3) calculation methods based on logging data (Han et al, 2018), 4) methods of actual measurement of underground in-situ stresses (Fu et al, 2021) and 5) simulation methods, including physical and numerical ones (Bai et al, 2018). In the study (Hashimoto and Matsu'Ura, 2006;Lü et al, 2017), the stress field simulation was performed using a simple three-dimensional geological model, whereas the geological unit was regarded as homogeneous and had constant mechanical parameters.…”