6),comprehensive damage coefficient(95%-98%)of fracture,and combining optimized fracture length and linearity sloping sanding programming,the optimization method of sanding concentration in fracturing design was formed.

For fracturing design,ahead fluid volume is an important operation parameter,which directly influences fracture morphology,fracture results or even results the success or failure of the operation.

According to such conditions as complicated geology, fracture development and low efficiency of fracturing stimulation in Daqingzi oilfield, which is one large oilfield with hundred million tons of reserves, the article describes the methods of fracturing design for naturally fractured reservoirs and difficulties of fracturing treatment .

Based on analysis of testing data interpreting the influence on factor of fracture op- eration,true friction of fracture fluid in stem is calculated accurately,pressure grade of fracture and temperature profile of crack are determined which direct fracture design and provide a reference for optimum of it.

The efficiencies of closure pressure and fracturing fluid in the reservoir are accurately obtained by using the new method, with which the main fracture design is made, proper proppant volume and total fracturing fluid volume are designed with successful field application.

On the basis of the characters of the reservoir, the classification criteria of fracturing optimization design was established and the optimization design was done to different reservoir.

In this paper,based on the fuzzy matter-element analysis and combined with concept of decision-making,a new method is proposed for evaluation and optimization of fracturing design program,which is called the decision analysis of optimal grade fuzzy matter-element.