特低渗砂岩油藏水平缝应力敏感实验研究及产能计算

发布时间：2018-04-18 12:04

  本文选题：水平裂缝 + 产能计算　； 参考：《西南石油大学》2015年硕士论文

【摘要】：特低渗砂岩油藏开发通常进行水力压裂,浅层储层压裂形成的裂缝以水平缝为主,且该类储层本身含有天然微裂缝,如我国大庆油田、延长油田、吉林油田等。在开发过程中随着地层压力下降,基质渗透率与裂缝导流能力均降低,油井生产指标与不考虑应力敏感时有较大差别,如产能、采出程度、地层压力等。此外,应力敏感实验测试方法和评价方法有待改进,考虑应力敏感的压裂水平缝油藏产能计算方法需进一步研究。 本文首先对应力敏感进行理论研究,确定岩石孔隙压缩系数和岩石渗透率有效应力系数；在理论研究的基础上对实验方法和评价方法进行改进,进行了天然岩心、人造裂缝岩心应力敏感实验测试及影响因素分析；最后将实验得到的应力敏感模型应用到油藏工程和数值模拟中,建立考虑应力敏感的压裂水平缝直井产能计算方法,分析了应力敏感和水平缝参数对压裂直井产能及其他开发指标的影响。 本文取得的主要研究成果如下： (1)推导出了岩石孔隙压缩系数表达式,岩石孔隙压缩系数与有效应力系数相关,随着孔隙度的减小岩石孔隙压缩系数降低。 (2)给出了一种简单的有效应力系数理论计算公式及一种简单的实验测定方法,有效应力系数的大小与岩石的孔隙度和泊松比有关,利用孔隙度和岩石泊松比可直接计算出岩石的有效应力系数。 (3)应力敏感实验测试优选采用有效应力系数修正的定内压变围压方法,可准确评价储层应力敏感性,该方法同时可将实际油藏高压条件转化为实验室低压条件进行。 (4)以储层原始有效应力为起点,特低渗砂岩基质应力敏感程度为中等偏弱。人造裂缝未填充时随着围压的增加渗透率急剧下降,卸载围压后渗透率恢复程度很低,应力敏感性中等偏强；裂缝填充后应力敏感性相对变弱,围压卸载后渗透率恢复程度变高,应力敏感性为中等。 (5)温度从30℃增加到150℃岩石渗透率损害增加了3.8%,应力敏感强度随着温度的升高略增大。此外,滑脱效应、时效性、驱替压产等对应力敏感实验测试存在影响。 (6)推导出了考虑应力敏感的压裂水平缝直井产能计算公式,该公式可应用于X油田产能计算,相对于现有的压裂水平缝直井产能计算方法误差更小。 (7)以X油田为例通过数值模拟分析得出：合理穿透比为0.5左右；水平缝临界导流能力为15D·cm左右；压裂水平缝间距为4m条比较合理；水平缝形状对产能影响不大；水平缝对称性对初期产量影响较大,对中后期影响很小。同时得出：只考虑渗透率应力敏感后单井日产量降低、采出程度降低、稳产期下降。
[Abstract]:In the development of ultra-low permeability sandstone reservoir, hydraulic fracturing is usually carried out. The fractures formed by shallow reservoir fracturing are mainly horizontal fractures, and this kind of reservoir itself contains natural micro-fractures, such as Daqing Oilfield, Yanchang Oilfield, Jilin Oilfield and so on.During the development process, with the decrease of formation pressure, the matrix permeability and fracture conductivity decrease, and the production index of oil well is different from that when stress sensitivity is not considered, such as productivity, recovery degree, formation pressure and so on.In addition, the stress sensitivity test method and evaluation method need to be improved, and the productivity calculation method of fracturing horizontal fracture reservoir considering stress sensitivity should be further studied.In this paper, the stress sensitivity is studied theoretically to determine the pore compressibility coefficient and the effective stress coefficient of rock permeability, and the experimental method and evaluation method are improved on the basis of the theoretical study, and the natural core is carried out.The stress sensitivity test of artificial fracture core and the analysis of the influencing factors are carried out. Finally, the stress-sensitive model is applied to reservoir engineering and numerical simulation, and the productivity calculation method of horizontal fractured straight well considering stress sensitivity is established.The effects of stress sensitivity and horizontal fracture parameters on productivity and other development indexes of fracturing vertical wells are analyzed.The main research results obtained in this paper are as follows:The pore compressibility coefficient of rock is related to the effective stress coefficient and decreases with the decrease of porosity.A simple formula for calculating effective stress coefficient and a simple experimental method are given. The magnitude of effective stress coefficient is related to porosity and Poisson's ratio of rock.The effective stress coefficient of rock can be calculated directly by using porosity and Poisson's ratio.3) the stress sensitivity test can be used to evaluate the reservoir stress sensitivity by using the effective stress coefficient modified local pressure variation method. The method can transform the actual reservoir high pressure condition into the laboratory low pressure condition at the same time.(4) taking the original effective stress of reservoir as the starting point, the stress sensitivity of the matrix of ultra-low permeability sandstone is moderate and weak.The permeability of artificial fracture decreases sharply with the increase of confining pressure, the recovery degree of permeability after unloading confining pressure is very low, the stress sensitivity is relatively strong, and the stress sensitivity is relatively weak after fracture filling.The permeability recovery degree becomes higher and the stress sensitivity is medium after confining pressure unloading.The permeability damage of rock increased from 30 鈩，

本文编号：1768298