NUMERICAL SIMULATION OF PRESENT GEO-STRESS FIELD AND ITS EFFECT ON HYDRAULIC FRACTURING OF FUYU RESERVOIR IN GAOTAIZI OILFIELD
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摘要: 利用微地震资料和岩石波速各向异性实验数据计算统计了高台子油田扶余油层相关井点的现今地应力方向, 并通过水力压裂资料及岩心古地磁定向、差应变、声发射实验得到井点的现今地应力数值; 结合岩石三轴抗压实验确定扶余油层的岩石力学参数, 在此基础上利用ANSYS软件建立研究区的有限元模型, 以井点现今地应力参数为约束条件, 对扶余油层现今地应力场进行数值模拟, 并分析了水力压裂施工时现今应力场及天然裂缝活动性对人工压裂缝的影响。研究结果表明, 高台子油田扶余油层水平最大主应力集中在34 MPa附近, 呈北东东-南西西向, 水平最小主应力为26~30 MPa, 方向北北西-南南东。断层带内有较高的应力值, 研究区西北部的背斜翼部水平主应力值较大, 而东部、南部较为平缓的背斜核部则是水平主应力的低值区。西部的背斜翼部及断裂带是天然裂缝的活跃区域, 天然裂缝对压裂缝的延伸方向影响较大; 东部的背斜核部平缓地带天然裂缝的活动性较低。Abstract: In the research of present geo-stress of Fuyu reservoir in Gaotaizi oilfield, the micro seismic data and the experimental data of rock velocity anisotropy are used to get the directions of present geo-stress of wells. On the other hand, hydraulic fracturing data and rock dynamic experiment including paleomagnetic experiment, differential deformation experiment and acoustic emission experiment are employed to determine the value of present geo-stress of wells. Triaxial rock mechanical test is conducted to get rock mechanics parameters of Fuyu reservoir. On these basis, we have built up the three-dimensional finite element model by ANSYS software, which utilized the present geo-stress parameter of wells as constraint condition to proceed the numerical simulation of present geo-stress of Fuyu reservoir and to analyze the impact on artificial fractures in the fracturing operation created by the activity of natural fracture and present geo-stress. The results prove that the value of maximum horizontal principal stress stays in 34 MPa and its direction is NEE-SWW and the value of Minimum horizontal principal stress varies from 26 MPa to 30 MPa and its direction is NNW-SSE. The stress value in fault zone and anticlinal flanks in the northwest is much higher. However the gentle anticlinal core in the eastern and the southern part are low value zones. The anticlinal flanks and fault zone in the west are the active zones of natural fracture. The direction of artificial fractures are mainly affected by the natural fractures; in the eastern anticlinal core, the activity of natural fracture is lower.
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Key words:
- Gaotaizi oil field /
- present geo-stress /
- numerical simulation /
- artificial fractures
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表 1 微地震监测及波速各向异性测试结果
Table 1. The results of microseismic monitoring and velocity anisotropy test
井号 测试方法 深度/m 水平最大主应力方向 模拟结果 高27-35 微地震监测 1654.2 NE 67.1° NE69.3° 高45-16 微地震监测 1844.1 NE 69.2° NE65.4° 高55-36 微地震监测 1749.3 NE 85.2° NE73.1° 高39-36 微地震监测 1686.2 NE 68.2° NE71.0° 高111-2 微地震监测 1776.5 NE 70.5° NE72.5° 高171 微地震监测 1779.4 NE 89.0° NE76.4° 太10-16 微地震监测 1739.6 NE 66.8° - 太46-30 微地震监测 1717.4 NE 67.5° - 高171 波速各向异性 1766.4 NE 87° NE76.4° 芳122 波速各向异性 1664.3 NE 79° - 太30-1 波速各向异性 1699.5 NE 33° - 葡51 波速各向异性 1693.4 NE 37° NE 42.6° 表 2 现今地应力数值测试及模拟结果
Table 2. The numerical value of the test and simulation results of present geo-sress
井号 测试类型 深度/m 垂向主应力/MPa 水平最大主应力/MPa 水平最小主应力/MPa 测试结果 模拟结果 测试结果 模拟结果 测试结果 模拟结果 高12-3 水力压裂 1775.2 - - 39.1 35.1 27.5 27.9 高12-斜2 水力压裂 1710.5 - - 38.0 34.9 27.4 27.3 高X1 水力压裂 2032.1 - - 38.5 - 29.5 - 太21-7 水力压裂 1553.4 - - 28.0 - 21.4 - 高171 差应变 1767.6 39.8 42.5 32.6 34.1 30.6 28.1 高171 声发射 1768.1 38.9 43.6 29.8 34.1 27.4 28.1 高171 声发射 1768.9 40.7 45.7 32.7 34.1 29.8 28.1 芳122 差应变 1649.9 37.2 41.9 30.4 - 26.5 - 表 3 地质模型岩石力学参数
Table 3. Rock mechanics parameters of geological model
地层 岩性 密度/(kg·m-3) 弹性模量/GPa 泊松比 扶一上 细砂岩 2440 15.57 0.170 扶一中 细砂岩 2460 15.17 0.169 扶一下 砂岩 2510 18.81 0.150 扶二上 砂岩 2550 23.97 0.204 扶二下 细砂岩 2550 20.91 0.136 断层 2200 12.00 0.250 -
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