Research On The Classification Evaluation And The Development Law Of Extra Low Permeability Reservoir In Yushulin Oilfield

Yushulin oilfield belongs to a typical large oil field of extra low permeability, low abundance, low yield. Fu Yang oil layer is the main exploitation. According to the two block water cut rising fast, three blocks to establish effective driving system, the classification evaluation and development law of extra low permeability reservoir is studied.In this paper,the reservoir characteristics and seepage law about Fu Yang oil layer of Yushulin oilfield blocks is studied. The method of reservoir comprehensive evaluation and classification is given. The parameter chart about Fu Yang oil layer of Yushulin oilfield reservoir is set up.the movable fluid percentage, movable oil percentage, starting pressure gradient can be obtained from the chart and permeability. Through the study of the pore structure, the gap of the pore radius distribution of different permeability core is not big,the average throat radius and permeability show a good linear relationship, the percentage of movable fluid and permeability show a good semi logarithmic relationship, the starting pressure gradient and permeability show a good power relationship. According to the five element classification method, combining with the initial stable oil production intensity, the Fuyang oil layer of Yushulin oilfield is divided into three categories.In this paper, the development law of different reservoir is given, and the adaptability of different reservoir was evaluated. The production decline formula and water drive characteristic equation of the special low permeability reservoir are derived. And fitting the production data, the change law of production in each block is in accordance with the law of exponential decline. By water drive characteristic curve fitting, the water cut rising rate in each block is evaluated. According to the characteristics of non Darcy flow, a model of the nonlinear seepage flow in a special low permeability reservoir is established. Using reservoir engineering methods, the use coefficient of different blocks was calculated in Fu Yang oil layer, reasonable well spacing of typical blocks is evaluated.