目标区块为典型的裂缝性致密砂岩储层,普遍具有超深、超高压、超高温、储层巨 厚和低孔、低渗,天然裂缝发育且被钙质充填或半充填的特点。如此复杂的地质条件导 致建井周期长、投资大,只有尽可能提高单井产量,才能实现气藏高效开发。但由于钻 井液污染严重,限制产能正常发挥,往往需要对其进行改造才能达到地质配产要求。该 区前期措施主要以基质酸化为主,往往不能有效解除深度污染;也进行了一些井次的小 规模压裂,压后增产23倍、增产潜力大,但施工过程中表现出施工压力高、加砂困 难、施工难度大等特点。针对裂缝性致密砂岩储层增产改造难点,报告提出体积酸压这 一新的改造思路,并通过模拟计算和室内实验对其可行性进行论证,具体内容如下: (1)报告建立了偏最小二乘法+BP神经网络数据分析模型,预测酸压过程中水力 裂缝能否沟通天然裂缝网络,计算结果表明目标储层在给定施工净压力下,作用模式以 水力裂缝转向天然裂缝延伸为主,有利于形成复杂的裂缝网络。 (2)报告研究了体积酸压酸蚀裂缝导流能力形成和保持机理,并以此为基础建立 了一套实验方法来评价形成的裂缝网络是否具备一定的导流能力。研究结果表明,在 30MPa的闭合应力下,目标储层裂缝导流能力可以达到1.50D‘cm,满足体积酸压改造 对导流能力的要求。 (3)报告筛选出可降解纤维辅助转向工艺,以提高储层纵向上改造程度。幵展纤 维封堵能力实验研究,并以实验结果为基础,给出了具体的施工建议。研究结果表明可 降解纤维辅助转向工艺可以有效地提高体积酸压改造效果。 (4)报告在室内实验和模拟计算基础上,完善了体积酸压工艺技术思路,并给出 了具体实现过-。选取典型井,对体积酸压工艺进行了现场验证。 综合分析&上研究结果,体积酸压工艺既能够有效增加储层横向上的泄流面积,又 能提高纵向上的改造程度,同时可以解除储层伤害,对于天然裂缝发育且裂缝中含有一 定充填物(钙质或钻井液)的致密砂岩储层有很好的适应性。本次研究为该类储层高效 开发提供了新的技术思路。 关键词:致密砂岩;裂缝性;体积酸压;可行性研究 I Abstract The target block is a typical fractured tight sandstone reservoir, which characterized by ultra-deep, ultra-high pressure, ultra-high temperature, thick reservoir, low porosity, and low permeability and natural fractures filled or half-filled by calcareous. Complicated geological conditions cause long well construction cycle and great investment. Only by maximizing production per well can achieve efficient development of gas reservoirs. However due to heavy pollution from drilling the normal production is limited. It is often needed to carry out stimulation to achieve its geological proration requirements. Previous measures in the target block are usually matrix acidizing,which cannot effectively remove deep pollution; There are also some small-scale hydraulic fracturing,which the production increases 2-3 times, showing great production potential. However there are some characteristics in construction process,such as high operating pressure,difficulty in filling sand. In order to solve difficulties in fracturing tight sandstone reservoir, this paper proposes a new stimulation ideas—volume acid fracturing, and through simulations and laboratory experiments to demonstrate its feasibility. Specific contents are as follows: (1) In this paper, a partial least squares + BP neural network data analysis model is established to predict whether the hydraulic fracture can communicate natural fracture network. The results show that under the given pressure in the target reservoir hydraulic fracture turning into natural fracture is the main mechanism, which is conducive to form a complicated fracture network. (2) The paper studies the formation and preserving mechanism of acid-etched fracture conductivity to evaluate whether the fracture network has a certain conductivity. A unified evaluation method is founded on the base of the established mechanism. The results show that under closure stress of 30MPa,the target reservoir fracture conductivity can reach as high as 1.50D-cmmeeting the requirement of conductivity in volume acid fracturing. (3) In order to improve the modification of reservoir vertically, this paper optimizes the degradable fiber diversion technique. Based on the result of experiment of fiber plugging ability, the practical suggestions are put forward. The result of research shows that the degradable fiber diversion technique can significantly enhance the effect of volume acid fracturing stimulation. (4) On the basis of simulations and laboratory experiments, the paper improves technical ideas of volume acid fracturing and gives specific implementation process; Selecting typical well, we carried out on-site verification for volume acid fracturing II Comprehensive analysis of the above research shows Hie volume acid fracturing technology can not only effectively increase the discharge area in landscape and the improvements in vertical, but also can remove the damage in reservoir at the same time. The technology has strong adaptability in tight sandstone reservoir that natural fractures developed, which contains certain fillings (calcium or drilling fluid). The study provides a new technology for the efficient development of the reservoir. Key words: tight sandstone; fracture; volume acid fracturing; feasibility research III 目录 第1章绪论 1 1.1研究的目的与意义 1 1.2国内外研究现状 1 1.2.1裂缝性致密砂岩储层改造工艺研究 1 1.2.2裂缝性储层水力裂缝延伸模式研究 3 1.2.3体积改造工艺研究现状 5 1.3主要研究内容及思路 6 1.3.1主要研究内容 6 1.3.2研究思路 8 第2章目标储层改造前评估 9 2.1储层地质特征分析 9 2.2储层裂缝发育及分布特征分析 9 2.3储层伤害特征分析 10 2.4目标区块前期工艺措施分析 10 2.4.1水力压裂施工参数统计及效果分析 10 2.4.2酸化施工参数统计及效果分析 11 2.5目标区块储层特点及改造要求 12 2.6体积酸压基本思路及定义 13 第3章体积酸压缝网形成可行性研究 14 3.1岩石脆性指数初步判断缝网形成难易程度 14 3.1.1岩石脆性指数方法简介 : 14 3.1.2目标储层岩石脆性指数计算 16 3.2水力裂缝与天然裂缝相交作用准则分析 16 3.3数据分析技术预测目标储层水力裂缝与天然裂缝作用模式 21 3.3.1方法简介 : 21 3.3.2确定输入层变量 22 3.3.3确定输出层变量 25 3.3.4预测结果表征方法 27 3.3.5获取训练样本数据 27 3.3.6训练样本数据 28 3.3.7预测结果分析 32 I 3.4本章小结 35 第4章体积酸压酸烛裂缝导流能力研究 36 4.1力学作用机理分析 36 4.1.1自支撑裂缝导流能力评价实验步骤 36 4.1.2实验结果分析 37 4.2化学作用机理分析 38 4.2.1酸液对韩质充填缝作用效果 38 4.2.2酸液对粗糙张开裂缝作用效果分析 40 4.2.3酸液对剪切滑移裂缝作用效果分析 42 4.2.4酸液对钻井液伤害缝作用效果研究 45 4.3本章小结 47 第5章目标储层体积酸压改造工艺研究 48 5.1体积酸压转向工艺研究 48 5.2纤维辅助转向压裂机理研究 48 5.2.1纤维辅助转向压裂技术原理 48 5.2.2实验用纤维性能分析 49 5.2.3可降解纤维封堵能力研究 51 5.3可降解纤维辅助转向压裂工艺设计 60 5.3.1纤维用量设计 :.60 5.3.2纤维携带液 61 5.3.3泵注排量 62 5.4体积酸压工艺技术思路及实现过程 62 5.5体积酸压工艺现场验证 63 5.5.1施工井储层基本情况 63 5.5.2体积酸压施工设计原则 63 5.5.3现场施工泵注程序 63 5.5.4体积酸压施工效果分析 64 第6章结论与建议 65 6.1结论 65 6.2 MiX 66 mm 67