Paleo structural stress field simulation for middle lower Ordovician in Tazhong area and favorable area prediction of fractured reservoirs

Key words:  Tarim Basin  Tazhong area  lower middle Ordovician  tectonic stress field  fractured reservoirs

Abstract:

Based on the fracture systems interpreted from seismic data, paleo tectonic map of bottom and top surface of middle lower Ordovician and cores fracture parameters statistics from over 40 wells, the middle lower Ordovician carbonate reservoirs in Tazhong area were studied from analysis of acoustic emission, stress measurement, rock mechanics parameters and uniaxial tensile test. Considering the influence of faults on the fracture forming, 3 D finite element method was applied to simulate paleo structural stress field of the middle Caledonian in Tazhong area. The simulation results show that during fracturing the maximum principal stress effective value ranges from 51.8 to 62.4 MPa, with the average value of 57.0 MPa, and the tensile strength ranges from 4.13 to 8.02 MPa, with the average value of 5.75 MPa. High value area of effective tensile stress is the favorable area for structural fractured reservoirs development, and most distributed in the interchange area of large fractured belts and part of the section of fractured zone. The distributed zone coincides with oil and gas wells and the Ordovician fracture developed zone defined by fracture linear density statistic data from actual drilling, which provides new geological evidences for oil and gas exploration of the area.