致密气藏压裂水平井反卷积试井模型

致密气储层的渗透率非常低，通常在0.1 mD以下，使得此类气井压裂后长时间无法达到地层径向流动状态，因此通过单个试井测试段数据无法解释出储层有效渗透率，进而无法确定水力裂缝有效半长；此外，井筒储集效应往往掩盖早期裂缝中的流态，导致裂缝导流能力这一关键完井参数求取困难。在缺失早期裂缝中流态和中期径向流态的情况下，如果强制拟合试井曲线，往往获得不唯一且偏差过大的参数解。针对这一问题，进行了反卷积试井分析方法研究。通过改进Schroeter反卷积数学模型并编制求解算法，实现了用短期试井数据和长期产量数据反演气藏瞬态压力响应历史的过程。数值试井算例验证了提出的反卷积模型及算法的正确性，反卷积后的瞬态压力响应去除了井筒储集效应，使裂缝线性流和地层径向流获得有效恢复。现场实例应用验证了提出的反卷积压力恢复试井分析方法的可行性，并证明短期的压力恢复试井数据亦能用于裂缝和储层动态参数计算，从而定量评价致密气藏水平井水力压裂施工效果。

Deconvolution-based well test model for the fractured horizontal wells in tight gas reservoirs

Tight gas reservoirs generally have low permeability (< 0.1 mD), in which the gas can hardly reach the radial flow state after well fracturing for a long time. As a consequence, the effective permeability of these reservoirs cannot be explained using the single-well test data, and then the effective half-length of hydraulic fracture cannot be determined. Besides, the gas flow state in early cracks is always unclear due to the well bore accumulation effect, thus causing great difficulties in the calculation of fracture conductivity (a key well completion parameter). When the flow state in early cracks and the medium-term radial flow state are unknown, the mandatory fitting of well-test curves may easily result in the non-unique parameter solutions with large deviations. To overcome this problem, this study proposes a deconvolution-based well-test analysis method. By modifying the Schroeter deconvolution mathematical model and formulating the solution algorithm, the transient pressure response history of gas reservoirs can be retrieved based on the short-term well test data and long-term production data. Furthermore, the correctness of the proposed deconvolution-based model and algorithm is verified using the numerical well test calculation equations. Results show that the transient pressure response after deconvolution can successfully eliminate the well bore accumulation effect and effectively recover the linear flows in fractures and radial flows in formation. Finally, the feasibility of the deconvolution-based pressure buildup testing method is proved through field application, but also demonstrate that the short-term pressure buildup well test data can also be used to calculate the dynamic parameters of fractures and reservoirs, and further quantitatively evaluate the hydraulic fracturing construction of horizontal wells in tight gas reservoirs.