Study On Complex And Multi - Crack Production Capacity Of Fractured Horizontal Wells In Strip Reservoir

Inrecent years, several large tight sandstonegas reservoirs are discovered in upper Palaeozoic of OrdosBasin, Xu jia he Formation of Sichuan Basin and deep formations of Kuqa,TarimBasin.There serve and production of tight sandgas have both experience drapid growth. andat that timethetight sandstone gas would become the key role innatural gasindustry. Multi-stage fracturing of horizontal wells (MFHW) is the main effective means to develop tight gas. Fracturing parameters optimization is an important part of the MFHW design, and production simulation of MFHW is the basis for optimization of fracture parameters.Though there are a lot of research of MFHW production simulation, some limitations exist in the following two aspects:As the fracturing technology is more and more elaborate, the way that treating the single frature as a whole to optimate is too simple and not consistent with the formation actual case.In order to adapt to the inflow pattern, sectional optimization of the fracture parameters along the different sements of fracture need to be more research. On the other hand with the continuous homogeneous large sandstone reservoir depletion, the banded linear composite heterogeneity resever of channel deposit become the important field of the development of tight gas. In the complex geological conditions, fracture location optimization aiming at maxiam productivity is an important problem.On the basis of point fource function, by Newman multiplication principle and superposition principle this paper builds a production prediction model of varying fracture width in heterogeneous reservoirs. The model can simulate varying width from fracture heel to the toe, non-uniform inflow along the fracture surface. With this modle this paper analyze the impact from the wedge fracture width to the production in different inflow patterns. On the basis of the varying fracture width model, this paper builds production prediction model of muti-wells and complex fracture system of MHFW. Then this paper analyzes the change law of fracture production at different locations in multi-well system and the fracture spacing optimization, the impact from the banch fractures to the whole production in different inflow patterns and the suitable geological conditions for complex fracrures and so on. On this basis, this paper puts forward some suggestions about flow conductivity optimization along the frature, the fracture parameters optimization of muti-well system and complex fracture system of MFHW.On the basis of heterogeneous reservoirs fractured horizontal well productivity prediction model,combing the point source function with the boundary element method, this paper build a MFHW production prediction modle which is suitable to banded heterogeneity reserves along the wellbore direction, which can be used to calculate the non-uniform inflow along the wellbore and the production of every single fracture. To highlight the heterogeneity of the reservoir, this model treat the crack as a whole. With this modle, thi paper analyze the inflow changes law along the wellbore and fracture production changes law in both homogenous and heterogeneity reserves, and then discuss the impact from factures to wellbore inflow and the impact from heterogeneity reserve to fracture production and so on. On this basis, this paper summarized the fracture spacing optimization sugguestion in banded heterogeneity reserves and apply it in the example muti-fractured horinzontal well.In summary, this paper expands the productivity prediction model of MHFW from the varying fracture width and heterogeneous reservoir, provides some guidance for fracture parameter optimization.