Abstract We analyzed drilling induced tensile fractures from resistivity image log data to ascertain the orientation of maximum horizontal stress (SH) from the eastern Illizi basin, Algeria. An average SH azimuth of 150°N (± 10°) has been interpreted from B-quality induced fractures, as per world stress map guidelines. The overall NW-SE orientation of SH translates to the relative plate motion of the African and Eurasian plates. Vertical stress (Sv) gradient of 1.07 PSI/ft has been derived from density log. Pore pressure estimated from sonic slowness reveals overpressure in Silurian shale, deposited in a transgressive depositional environment, whereas Devonian and Ordovician hydrocarbon reservoirs have been seen to be normally pressured. Poroelastic strain model has been employed to quantify maximum and minimum horizontal stress (Sh) magnitudes. An effective stress ratio of 0.6, interpreted from leak-off test has also been used to model Sh. Using frictional faulting theory, upper limit of SH has been quantified. SH/Sv ratio of 1.04 (1.01–1.26) has been seen in the study area. Based on the relative stress magnitudes (SH > Sv > Sh), a present day strike-slip faulting regime has been inferred in the eastern Illizi basin, Algeria. Fault reactivation potential at reservoir level has been inferred from stress polygon analysis.

中文翻译：

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阿尔及利亚伊利齐盆地东部水平应力分量的现今地应力大小和方向：地质力学模型

摘要 我们从电阻率图像测井数据中分析了钻井诱发的拉伸裂缝，以确定阿尔及利亚伊利齐盆地东部的最大水平应力 (SH) 的方向。根据世界应力图指南，已从 B 级诱导裂缝中解释了 150°N (± 10°) 的平均 SH 方位角。SH 的整体 NW-SE 方向转化为非洲和欧亚板块的相对板块运动。1.07 PSI/ft 的垂直应力 (Sv) 梯度已从密度测井导出。根据声波慢度估计的孔隙压力揭示了志留系页岩中的超压，沉积在海侵沉积环境中，而泥盆纪和奥陶纪油气藏已被视为正常加压。多孔弹性应变模型已被用于量化最大和最小水平应力 (Sh) 的大小。从泄漏测试解释的 0.6 的有效应力比也已用于模拟 Sh。使用摩擦断层理论，已经量化了 SH 的上限。在研究区已经看到 SH/Sv 比率为 1.04 (1.01–1.26)。根据相对应力大小 (SH > Sv > Sh)，在阿尔及利亚伊利齐盆地东部推断出现今的走滑断层机制。已从应力多边形分析中推断出油藏层的断层再活化潜力。在阿尔及利亚伊利齐盆地东部推断出现今的走滑断层机制。已从应力多边形分析中推断出油藏层的断层再活化潜力。在阿尔及利亚伊利齐盆地东部推断出现今的走滑断层机制。已从应力多边形分析中推断出油藏层的断层再活化潜力。