Research On Fracture Developing Characteristics Of Chang 6₃ Reservoir, Yanchang Group In Huaqing Area, Changqing Petroleum Field

Super-low permeability is the basic characteristic of the reservoir in the Ordos Basin. The fractures play an important role in enlarging the reservoir capability and improving the oil and gas production. So the deep research of the fracture developing characteristics would be much meaningful for directing the oil and gas exploration in the low permeable reservoir and exploiting reasonably.The chang 63 reservior is acted as the research aim in Yanchang group, Huanqing area, the Ordos Basin. The research is processing on the tectonic fractures combining with the traditional fracture research way, rock experiments and finite element modeling and the research area is firstly divided into the follow six types of districts:high deliverability of high fractural density districts, mid-high deliverability of high fractural density districts, low-mid deliverability of high fractural density districts, mid-high deliverability of low fractural density districts, low-mid deliverability of low fractural density districts, and low deliverability of low fractural density districts.Through the analysis of the rock experiments of different stain analysis, acoustic emission, rock compression, palaeomagnetism and hydrafracturing, conclusions are as follow:Through the analysis of the rock experiments of different stain analysis, acoustic emission, rock compression, palaeomagnetism, acoustic wave speed, polished slice, cast slice, and scanning electron microscope, percentage of voids and permeability, image logging, and drilling bore breaking, two conclusions are gained:on one hand, the direction of the maximum principal stress of Yanshannian tectonic stress field is NWW, the dominant direction is 116°-296°, the value is 74.06-105.31MPa, the average value is 84.53MPa; the direction of the present maximum horizontal principal stress is NEE—SWW, the dominant direction is 76°-256°, the value of the present minimum horizontal principal stress is 28.86-36.65MPa, the average value is 31.85 MPa; on another hand, the direction of chang 63 reservoir of Yanchang group in Huaqing area is mainly trending NE-NEE and EW-NWW.Base on the analysis attainment of the experiments, applying for the finite element modeling method, the distribution pattern of the aim reservoir tectonic stress field from later Mesozoic has been imitated. Simultaneously, according to the quantitative counting data of the fractures developing in the rock cores, the prediction mathematical model of the tectonic fractural density is founded to predict the fractural distribution rules. Pursuant to the above outcome, the model of reservoir fractural distribution network is established.