The purpose of frac fluid flowback is to outflow the fracturing fluid and prevent the proppant backflow, which determines the effect of fracturing fluid flowback. The fracturing treatment in field lacks relevant theoretical models for prediction. Therefore, this work focuses on establishing the flowback model of hydraulic fracturing for multilayer fractured wells. Then the wellhead pressure and fluid flowback volume are predicted based on the actual parameters of fracturing treatment in the process of flowback and are compared with the field data of frac fluid flowback. Results show that the wellhead pressure and fluid flowback volume calculated by the model are consistent with the field data. The sand production ratio of the three wells during the flowback process is lower than 1% indicating that the optimized parameters achieve the purpose of flowback operations and reduce the flowback volume of the proppant.

Hydraulic fracturing is an effective measure to increase oil production for the development of low permeability reservoir. The selection of perforating parameters has a direct effect on the fracture expansion, formation fracture cracking pressure and even the implementation success of fracturing in that the fracturing processing fluid and artificial fracture all need to pass through the extension of perforation. In field application, the selection of perforating parameters is usually determined base on experience without combining with the actual data of the hydraulic fracturing wells. This work focuses on analyzing the influence of perforating parameters on the productivity of fractured well based on an established productivity prediction model through analytical method.Results show that, take a specific area of Changqing oil field for example, the perforation diameter has little effect on the productivity after fracturing, the other optimized perforating parameters are as follows: the perforation degree 30~40%, perforation density 8~12 perforation per meter, perforation depth 0.2~0.3m. The results are helpful to guide the optimization of perforating parameters in low permeability reservoir.

In general, the scale of production, exploitation period and the economic benefits of oil and gas field are, to a large extent, depended on the selection, deployment and adjustment of well patterns, especially for tight reservoir. So far, some problems exist in Changqing low permeability oil field, such as the effective displacement system is not easy to be established, a low utilization efficiency of injection water, low oil production and so on. Therefore, five kinds of different well pattern schemes are designed. Then, the well pattern schemes are optimized through numerical simulation method based on the exploitation index including the daily oil output per well, moisture content and oil recovery. Results show that the well patterns of horizontal-vertical wells have better development efficiency than the well patterns of vertical wells. For the optimized well pattern, when the horizontal segment length of horizontal well is 300m, the optimalizing well spacing is 400m and the optimalizing row spacing is 100~150m.

The future of the energy sector in the coming years is expected to be significantly affected by unconventional gas resources. Flow through porous media has many applications in the chemical, petroleum, gas, and pulp and paper industries, as well as in soil remediation and material characterization. In petroleum and natural gas production, flow through porous media has significance in the production of gas and/or oil. There are many characteristics of tight reservoir rock resulting in high and complex water saturation such as tiny pore throat, poor sorting, high displacement pressure, and so on. The one hand, the gas seepage is affected by the slippage effect, resulting in the abnormal gas relative permeability. On the other hand, the residual water of the tight core is controlled by displacement pressure. This study is directly related to gas reservoir engineering and is specifically focused to obtain fundamental information for two phase flow through low permeability porous media (Tight Sand Gas).