Study On Evolutionary Process Of Ground Stress Field In Different Geological Periods

The ground stress research occupies the important position in exploration and development of oil and gas field. This paper has studied evolutionary process of ground stress field in different geological periods to the paleo-central uplift belt of northern Songliao basin. According to predecessor's research results, this paper has used the 3-D seismic data and geological information with key layer interface of the paleo-central uplift belt fully, summarized the paleo-central uplift belt structure characteristic, reproduced evolution course of the paleo-central uplift belt through structure development history profile map. Meanwhile, carried on the ground stress experiment on the core sample, it obtained that the typical layers of mechanical properties (modulus of elasticity, poisson's ratio and so on) and the ground stress size and the direction of the key well position to provide the basis for the numerical simulation. On this basis, by simulating ground stress field of the typical layers in three geological period with thin plate-bending trend surface method and 3-D finite element method, which are Denglouku group's bottom and Quantou group's bottom nowadays, Yingcheng group's deposit in latter stage Yingcheng group's bottom, Shahe group's deposit in latter stage Shahe group's bottom respectively, it obtained that the paleo-central uplift structure is the primary factor that affects this area overall ground stress field distribution, but the fault has greater influence on the local area stress field's size and the direction. Through two kinds of simulation methods results and actual comparison, it is analyzed and obtained that the simulation stress field is basically coincided with the actual stratum stress field nowadays, and infered the simulation stress field of the ancient geological period also to coincide with the real ancient structure stress field. Finally, based on the distribution of the stress field which the 3-D finite element method has simulated, this paper predicted the fracture of the paleo-central uplift belt in Griffith and Coulomb-Navier rupture criterion quantitatively, and the results indicated that the fault (regmagenesis) had an important influence on the fracture growth.