深层碳酸盐岩储层改造理念的革新——立体酸压技术

酸化压裂是碳酸盐岩油气藏高效开发不可或缺的手段,对于深层、超深层海相碳酸盐岩油气藏,由于其工程地质特征的特殊性,通过现有的酸化压裂技术要形成复杂裂缝网络难度大。为了实现深层、超深层碳酸盐岩油气藏的高效立体开发,从我国深层海相碳酸盐岩油气藏的工程地质特征出发,揭示了该类储层酸压改造的难点;然后,以实现该类油气藏高效立体开发为目标,充分借鉴体积酸压、深度酸压等技术,提出了立体酸压的技术理念,阐明了其技术内涵,并且详述了立体酸压所包含的关键技术,进而指出了下一步的发展方向。研究结果表明:(1)立体酸压技术包括3个基本内涵——根据储层类型选择相应的酸液深穿透技术,实现储层平面上的充分改造;形成在高闭合压力下具有较高导流能力的复杂酸压裂缝体;沿长井段合理部署酸压裂缝体,实现储层在井筒方向上的充分改造。(2)立体酸压包含3项关键技术——多场多尺度多流体耦合作用下酸液有效作用距离预测技术;酸压复杂裂缝体导流能力优化技术;水平井/大斜度井长井段储层精细布酸技术。(3)要推动立体酸压技术的进一步发展,还需要开展3个方面的科研攻关——超深储层破裂压力预测及降低破裂压力技术;强非均质储层酸压裂缝体形态预测技术;深度超过7 000 m长井段储层分段动用技术和新型耐高温、缓速、低摩阻系数液体技术。

An innovative concept on deep carbonate reservoir stimulation: Three-dimensional acid fracturing technology

Acid fracturing is an indispensable technology in the efficient development of carbonate oil and gas reservoirs. As for deep and ultra-deep marine carbonate oil and gas reservoirs, however, existing acid fracturing technologies can hardly create complex fracture networks because of their particular engineering and geological characteristics. In order to realize the efficient three-dimensional development of deep and ultra-deep marine carbonate oil and gas reservoirs, this paper revealed the acid fracturing difficulties of this kind of reservoirs based on the engineering and geological characteristics of deep marine carbonate oil and gas reservoirs in China. Then, taking the efficient three-dimensional development of deep and ultra-deep marine carbonate oil and gas reservoirs as the target, the technical concept of three-dimensional acid fracturing (3D-AF) was put forward based on the techniques of volume acid fracturing and deep acid fracturing. In addition, its technical connotation was illustrated and its key technologies were described in detail. Finally, its development direction in the next step was pointed out. And the following research results were obtained. First, the 3D-AF technology contains three basic connotations: (1) selecting the corresponding acid penetration technology according to reservoir types so as to realize sufficient reservoir stimulation in plane; (2) creating complex acid-fracturing fracture volume with higher flow conductivity under high closed pressure; (3) deploying acid-fracturing fracture volume rationally along the long hole section so as to realize sufficient reservoir stimulation in the wellbore direction. Second, there are three key technologies of 3D-AF, i.e., the technology for predicting the effective acid-penetrate distance under the coupling action of multi-field, multi-scale and multi-fluid, the technology for optimizing the flow conductivity of complex acid-fracturing fracture volume, and the technology for precisely deploying acid in the long section of horizontal well or highly deviated well. Third, in order to promote the further development of 3D-AF technology, it is necessary to carry out researches on three technologies, i.e., the technology for predicting and reducing the fracturing pressure of ultra-deep reservoir, the technology for predicting the geometry of acid-fracturing fracture volume in strongly heterogeneous reservoir, and the staged reservoir production technology and new fluid technology with high temperature resistance, low reaction rate and low friction resistance coefficient for long hole sections (over 7 000 m).