Recently, the Engineering Institute of North China Oil and Gas Branch completed part of the section construction by using 30/50 mesh quartz sand instead of 20/40 mesh ceramsite proppant in the fracturing reconstruction of dense reservoirs in Niudi Gas Field, and achieved good production. Dense reservoir belongs to unconventional reservoir. Among the cost components of fracturing in tight sandstone reservoir, the cost of fracturing proppant accounts for 20% to 25% of the total fracturing cost. Reducing the cost of fracturing material is the key to cost reduction.
　　In order to reduce cost and expense, the engineering institute, through investigating the application of quartz sand in North America and reef dam shale gas reservoirs, combined with the closed pressure characteristics of tight reservoirs in Daniudi gas field and a large number of laboratory experimental results, on the basis of guaranteeing the effect of reservoir transformation, determined the reservoir with depth less than 2700m, and adopted the ratio of quartz sand to ceramsite. The field test scheme of value 3:7 is put forward, and a two-step technical idea is put forward. Firstly, some wells are selected to carry out the test, and their production performance is tracked after half a year and one year, and the subsequent application is determined according to the evaluation results.
　　As of April 17, three horizontal wells have been tested in situ. From the initial production, the output after pressing is not affected by the conductivity of quartz sand. The next step is to follow up and evaluate the long-term effect. The quartz sand instead of ceramsite test will be carried out step by step, which will help North China Branch to ensure efficiency and reduce cost.
　　Remarks:
　　In deep oil and gas wells, after fracturing treatment of high closed pressure and low permeability deposits, hydrocarbon-bearing strata are fractured, and oil and gas are gathered from the channels of fracture formation. At this time, it is necessary to inject fluid into the rock base to exceed the pressure of the formation rupture strength, so that the rock around the wellbore produces cracks, forming a channel with high laminar flow capacity.
　　The commonly used proppants are quartz sand, bauxite ceramsite sand and resin-coated composite particles. Quartz sand is widely used because of its low cost, low density and easy pumping. However, it is not suitable for deep wells with high closure pressure because of its low strong bottom and poor sphericity, which reduces fracture conductivity.