【作者】 孙庆友；

【导师】 刘义坤；

【作者基本信息】 东北石油大学 ， 油气田开发工程， 2011， 博士

【摘要】 大庆外围油田高含水井数多,见水层位多,并且多为主力油层,由于外围油田主要以压裂方式投产,所以多为裂缝型见水,采出程度低,而随着油田开发,高含水井的数量逐年增加。对于这些油井,常规的同井同层重复压裂技术或堵水技术已不利于高含水层的剩余油挖潜,措施效果较差,因此,最终导致高含水井关井。这些油井的关停,不仅影响油田注采结构的调整,而且造成了大量的资产闲置。为了进一步挖掘剩余油,必须进一步探索适用于高含水油井的剩余油挖潜技术。如果要在大庆外围低渗透油田进行规模化施工,还存在选井选层标准、优化施工工艺及其他低渗透油田的适应性等一系列问题,必须通过工业化现场试验加以解决。如果能在试验中解决上述存在问题,将为低渗透油田进入中高含水的有效开发提供技术支持,对提高外围“三低”油藏动用程度,为确保油田持续稳产4000万吨做出重要贡献,有着长远的经济效益和社会效益,具有重要的意义。本文通过大量调研国内外油藏重复压裂造缝机理的研究成果,以前人工作为基础,对大庆低渗透裂缝性油藏重复压裂造逢机理进行了研究,并基于油藏数值模拟建立了数值模拟模型,对剩余油分布进行了分析,根据正交设计法和灰色关联法对措施增油的敏感性进行了分析,并利用盈亏平衡原理求解了压裂措施的经济界限,编制了软件,求出的经济界限结果与油田实际情况吻合。本文的主要研究内容及认识如下：总结了裂缝性油藏的地质特征和开发特征,为研究裂缝转向问题,首先建立了现今总应力场的力学模型,计算10C76-118井周围的总地应力场,并求解了应力场叠加后的总应力场数据。针对裂缝的力学特征,研究了重复压裂裂缝起裂的力学准则。根据重复压裂造新缝的力学条件,对重复压裂产生新缝进行了力学分析,从而确定了在考虑完全拉伸破坏和考虑完全剪切力破坏的启裂角度,进一步确定出裂缝的启裂角θP,应满足的条件：0°<θP,<45°。根据重复压裂裂缝周围的应力分析,结合边界条件计算边界应力影响系数,并对重复压裂裂缝的影响因素进行分析,模拟出C55区块生产1000天后的地应力场分布,从而得到重复压裂裂缝的延伸轨迹。利用Petrel软件建立区块的三维地质模型,利用Eclipse软件建立数值模拟模型,对和产历史进行修正,进而分析区块剩余油分布规律,得出前期的拟合较后期的符合率高,全区拟合符合率达到90%以上,单井符合率在85%以上,压裂后的水淹半径比压裂前的水淹半径略大,这与实际结果足相吻合的。对区块的累积产油量进行单因素分析,结合灰色关联原理和正交分析法,对影响压裂的因素进行了敏感性分析。根据盈亏平衡原理,结合成本、收益、税金的计算公式,确定了不同指标条件下压裂措施的技术经济界限,并编制了软件。更多还原

【Abstract】 There are many high water cut wells and breakthrough layers in the Daqing peripheral oilfields, most of those breakthrough layers are main formations. As peripheral oilfields put into production in fracturing way, fracturing water breakthrough and low recovery are common, and with the oilfield developing the number of high water cut wells increases year by year. For these wells, multiple fracturing and water plugging technology in the same well and layer are not good for remaining oil development of high aquifer, and measure effect is poor which resulting in high water cut wells shut-in finally. The shut-in of these wells not only affected the adjustments of injection-production strategy, but also caused large idle assets. In order to develop remaining oil further, we must explore remaining oil seeking technology adapt to the high water content wells. To operate in the peripheral low-permeability oil fields of Daqing at large scale, there are a range of issues need to be solved by field tests, such as the criteria of selecting well and layer, operation optimization and adaptability to other low permeability oil fields. If problems mentioned above can be solved by field test, it will provide technical support for low-permeability oilfield development during high water cut stage and it will be significant for improving the producing degree of peripheral "three low" reservoir and ensure the oilfield stable yield 40 million tons/a. All of these have long-term economic and social benefits.In this article, according to a large number of researches about reservoir multiple fracturing mechanism at home and abroad, based on the previous work, we studied the multiple fracturing mechanism of low permeability fractured reservoirs in Daqing. Based on the numerical simulation model, we analyzed the remaining oil distribution, according to the orthogonal design method and grey correlation method, we analyzed the sensitivity of reservoir stimulation, by means of breakeven analysis, and we got the fracturing economic limits and developed software. The economic limits resulted coincided to actual field. The main results of the article are as follows:We summarized the geological and development characteristics of fractured reservoirs. In order to study fracture steering, the mechanical model of the total stress field is established, the total stress field around the well 10C76-118 is calculated and the total stress field data after stress field superposition is solved. According to mechanical characteristics of the fractures, we discussed the multiple fracturing mechanics criteria.Based on the mechanical conditions of multiple fracturing for new fractures, we made mechanical analysis on the new fracture, thus the fracture initiation angle is determined under the condition of completely tensile failure and total shear destruction, further determined the condition fracture initiation angle should satisfied with:0°<θn< 45°.According to the stress analysis around the multiple fracturing fractures, we calculated the boundary stress influence coefficient, analyzed factors impacting on the multiple fracturing fractures, the stress field distribution after 1000 days in C55 blocks is simulated, and then we obtained the extension track of multiple fracturing fractures. The 3D geological model of block is built with Petrel software, the numerical simulation model is established with Eclipse software, and we corrected the production history, analyzed remaining oil distribution for the block. We found that the coincidence rate for earlier stage fitting is better than the later one. The coincidence rate of the whole region fitting is more than 90%, and the single well compliance rate is over 85%. The flooding radius after fracturing is larger than the one before fracturing, which is consistent with the field results.We made single factor analysis on cumulative oil production of block, and analyzed the sensitivity of factors affected fracturing combined with the orthogonal design theory and grey correlation method. According to breakeven analysis, the technical and economic limits of fracturing for different index are determined with the cost, revenue and tax formula, and we developed the software for it.更多还原