A Study On Evaluation And Application Of Well Pattern On Fuyang Reservoir In Yushulin Region

The low permeability reservoirs in our country are mainly composed of sandstone, with natural fractures varying degrees. The low permeability reservoirs can be brought on stream by hydraulic fracturing, and make hydraulic and natural fractures coexist. The open of natural fractures and the hydraulic fractures direction are obviously controlled by the greatest principal-stress orientation of ground stress field, and together make horizontal permeability of these types of reservoirs heterogeneous. Therefore, the well placement and optimization of the low permeability reservoirs must be combined with fracture system. In this paper, taking Yushulin ultra-low permeability reservoir as an example, the finished research contents are as follows.1. The finite element computation module of two-dimension stress field considering fractures after first fracturing is established. The change law of stress field varying with time has been studied, and the extended distance of fractures has been determined, which provide theoretical guidance for reasonable well pattern arrangement.2. The well pattern arrangement for fractured ultra-low permeability reservoir is preliminarily studied. The anisotropy of permeability, filtrational resistance and effective driving distance of Yushulin ultra-low permeability reservoir caused by hydraulic fracturing, is analyzed. The well spacing and the row spacing on the condition of different permeability and different permeability ratios are calculated.3. The equivalent medium model of fracturing ultra-low permeability sandstone reservoir is established, and the influence of different fracture densities and matrix permeability on equivalent permeability in different directions is analyzed. On the basis of the seepage characteristics of developed naturally fracturing ultra-low permeability reservoir, the relationship between critical spacing and row spacing is studied and derived.4. Taking Yushulin ultra-low permeability reservoir for example, the appropriate allocation between flooding well network and fracture system of fracturing ultra-low permeability reservoir. The influence of permeability ratio and different well pattern on the development effectiveness of low permeability field is analyzed. And the adjustment and deployment of vertical flooding well network system in some developed areas in Yushulin field is researched.