In this paper, the sensitivity factors of CO2 huff-n-puff for multifractured horizontal wells (MFHWs) in tight oil reservoirs were investigated through an experimental test and numerical simulation. The pressure-volume-temperature (PVT) experiment and the slim tube experiment are used to understand the interaction mechanism between CO2 and crude oil, and the minimum miscibility pressure (MMP) of the CO2-crude oil system is 17 MPa. The single-well model was firstly established to analyze the sensitivity factors on production performance of MFHWs by using CO2 huff-n-puff. The controlling factors of CO2 huff-n-puff for MFHWs in tight oil reservoirs were divided into three categories (i.e., reservoir parameters, well parameters, and injection-production parameters), and the impact of individual parameter on well performance was discussed in detail. The range of reservoir parameters suitable for CO2 huff-n-puff of MFHWs is obtained. The reservoir permeability is from 0.1 mD to 1 mD, the reservoir thickness changes from 10 m to 30 m, and the reservoir porosity is from 7% to 12%. Based on the reservoir parameters of the target reservoir, the reasonable well and fracture parameters are obtained. The sensitivity intensity was followed by the horizontal well length, fracture conductivity, fracture spacing, and fracture half-length. CO2 injection-production parameters are further optimized, and the sensitivity intensity was followed by the single-cycle cumulative CO2 injection rate, the soaking time, the injection rates, and the production rates. It provides a reference for parameter optimization of CO2 huff-n-puff for MFHWs in tight oil reservoirs.

中文翻译：

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致密油藏多压裂水平井CO2 Huff-n-Puff性能优化

本文通过试验和数值模拟研究了致密油藏多压裂水平井(MFHWs) CO2吞吐的敏感性因素。通过压力-体积-温度（PVT）实验和细管实验了解CO2与原油的相互作用机理，CO2-原油体系的最小混相压力（MMP）为17 MPa。首次建立单井模型，分析了CO2 huff-n-puff对MFHWs生产性能的敏感因素。将致密油藏MFHW的CO2 huff-n-puff控制因素分为三类（即油藏参数、井参数和注采参数），详细讨论了各个参数对井性能的影响. 获得了适合MFHWs CO2 huff-n-puff的储层参数范围。储层渗透率0.1 mD~1 mD，储层厚度10 m~30 m，储层孔隙度7%~12%。根据目标储层的储层参数，得到合理的井和裂缝参数。敏感性强度依次为水平井长度、裂缝导流能力、裂缝间距和裂缝半长。进一步优化CO2注采参数，敏感性强度依次为单周期累积CO2注入量、均热时间、注入量、采出量。为致密油藏MFHWs CO2 huff-n-puff参数优化提供参考。