Study On The Technique Of Controlling Hydraulic Crack Height Extension

At present, the low permeability oil and gas reserves make up the majority of total resources in our country. They can be developed and utilized economically only after fracturing, however, in order to get high fracture, conductivity, it must be long fractures, at the same volume of fracturing fluid and proppants, for getting long fractures, we must control the fracture height extension. The fracture height is excessive, the main hazards are:connected the gas cap in the upper reservoir, connected the water at the bottom of the reservoir, connected different pressure systems of reservoir and waste of fracturing fluid and proppants, increase the cost of fracturing treatment, and proppant support effect is not ideal. So the control of fracture height extension technique is one of the key technologies in the economic and effective exploitation of low permeability oil and gas fields.In this paper, base on the study of fracture height extension control technology, obtained the following results:(1) Investigate the research status of control the fracture height extension technology at home and abroad, and analyzes the factors that influence the fracture height extension, it provides a theoretical basis for study of fracture height control technology.(2) Established the crossing or slippage criterion when fracture extension to the discontinuous interface (natural fractures and bedding plane, etc.), and program to predict fracture extension behavior at the interface. If fractures cross the rock interface, the fracture height is not controlled, it is needed to use the fracture height control technology to control the fracture height extension; If fracture slip along the interface, the fracture height under control to a certain extent, it is not needed artificial barriers fracturing technology to control the height of fracture.(3) The wellbore and fracture temperature field model, quasi three dimensional fracture propagation model are established, using VB to compile conventional hydraulic fracturing fracture extension procedures without artificial barriers, it can be used to calculated hydraulic fracturing fracture geometry under the condition of different pump injection considering fracturing fluid temperature change.(4) Set up the diverter migration model, fracturing fluid filtration model, artificial barrier thickness calculation model at different pump stop time and fracture propagation model after joining artificial barrier, using VB to compile artificial barrier control the fracture height extension procedures.(5) Set petrophysical parameters and in-situ stress in XX oilfield for example, use the program to calculate the fracture extension behavior, and analyzes the influence of various parameters on the fracture height; And the contrast of fracture geometry shapes between joining artificial barrier and without artificial barrier, verify the validity of the artificial barrier to control the fracture height extension technology.This paper mainly has carried on the theoretical research to control the fracture height extension technology from the above five aspects, it has certain guiding significance for fracture height control fracturing treatment.