Study on an Acid Soluble LCM Used for Multi-Target Well in Tahe Oilfield
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摘要: 塔河油田碳酸盐岩油藏欠发育区储层缝洞规模小,单井难以实现经济开发,通过采用“一井多靶”钻井穿过多个缝洞储集体,可有效提高单井产能,而钻遇的复杂缝洞漏失问题制约了钻井工程提速提效。针对碳酸盐岩储层堵漏技术难点,分析储层漏失特征及堵漏需求,研制了一种可酸溶凝胶颗粒,酸溶率大于86%,膨胀倍数为3~5倍,膨胀后具有良好的韧性和变形性。基于凝胶颗粒堵漏机理,采用正交实验方法,形成了与可酸溶凝胶颗粒协同复配可酸溶的矿物柔性纤维、片状等材料的可酸溶凝胶复合堵漏剂,抗温150 ℃,酸溶率大于85%,适应0.1~3.0 mm裂缝和4~10目的孔隙,正向承压强度大于9 MPa,反向承压强度大于5 MPa,现场应用效果表明,该堵漏技术可解决碳酸盐岩储层复杂的缝洞漏失问题,应用前景广。Abstract: The underdeveloped carbonate reservoirs in the Tahe Oilfield have fractures and vugs that are small scaled and production through a single well generally cannot realize its expected economy. Use multi-target well to penetrate multiple fractured reservoirs or reservoirs with vugs through one well, the production potential of a single well can be economically increased. The problem with the multi-target well drilling is mud losses in the complex fracture structures, which restrict the realization of fast and high efficiency drilling. By analyzing the characteristics of the mud losses taking place in fractured reservoirs and the difficulties encountered during drilling, an acid-soluble gel particle lost circulation material (LCM) was developed to solve the mud losses in reservoir drilling. Percent acid solubility of this LCM is 86%. After swelling, the volume of the LCM can be 3-5 times of its original volume, and the swollen LCM has good toughness and deformability. The acid soluble gel particle LCM, through orthogonal test, was mixed with an acid soluble flexible fiber and a flaky material to form a compound acid soluble LCM based on the mechanisms of mud loss control with gel particles. The compound LCM can be used at temperatures up to 150 ℃ and has percent acid solubility of 85%. It can used to stop mud losses through fractures of 0.1-3.0 mm in width and pores of 4-10 mesh. The pressure bearing capacity of the LCM layer is 9 MPa on the front side and 5 MPa on the opposite. Field application has shown that this compound acid soluble LCM can be used to solve mud losses into the complex fractures developed in carbonate rock reservoirs and should have broad application prospects.
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表 1 凝胶颗粒的酸溶率
m实验前/g m实验后/g 酸溶率/% 平均值/% 2.00 0.278 86.10 86.20 2.01 0.277 86.22 2.02 0.277 86.29 表 2 实验因素与水平表
因素 凝胶
颗粒A/%牡蛎壳
B/%柔性
纤维C/%超细
碳酸钙D/%水平1 1 4 1 4 水平2 3 6 2 8 水平3 5 8 3 12 表 3 实验方案及结果
序号 因素 结果 A B C D 流动度/
cm漏失量/
mL驻留长度/
cm封堵强度/
MPa1 1 4 1 4 27 154 15.3 3.2 2 1 6 2 8 24 132 13.4 3.5 3 1 8 3 12 19 123 12.3 4.4 4 3 4 2 12 19 94 8.5 7.3 5 3 6 3 4 23 101 10.1 6.6 6 3 8 1 8 20 82 9.4 7.6 7 5 4 3 8 17 54 7.2 9.4 8 5 6 1 12 15 35 4.1 11.8 9 5 8 2 4 18 43 6.4 8.7 表 4 各指标实验结果极差法分析
指标 流动度/cm K1 70.0 63.0 62.0 68.0 K2 62.0 62.0 61.0 61.0 K3 50.0 57.0 59.0 53.0 K1* 23.3 21.0 20.7 22.7 K2* 20.7 20.7 20.3 20.3 K3* 16.7 19.0 19.7 17.7 R(极差) 6.7 2.0 1.0 5.0 指标 漏失量/mL K1 409.0 302.0 271.0 298.0 K2 277.0 268.0 269.0 268.0 K3 132.0 248.0 278.0 252.0 K1* 136.3 100.7 90.3 99.3 K2* 92.3 89.3 89.7 89.3 K3* 44.0 82.7 92.7 84.0 R(极差) 92.3 18.0 3.0 15.3 指标 驻留长度/cm K1 41.0 31.0 28.8 31.8 K2 28.0 27.6 28.3 30.0 K3 17.7 28.1 29.6 24.9 K1* 13.7 10.3 9.6 10.6 K2* 9.3 9.2 9.4 10.0 K3* 5.9 9.4 9.9 8.3 R(极差) 7.8 1.1 0.4 2.3 指标 封堵强度/MPa K1 11.1 19.9 28.8 18.5 K2 21.5 21.9 28.3 20.5 K3 29.9 20.7 29.6 23.5 K1* 3.7 6.6 9.6 6.2 K2* 7.2 7.3 9.4 6.8 K3* 10.0 6.9 9.9 7.8 R(极差) 6.3 0.7 0.4 1.7 表 5 不同实验指标的最优水平组合
实验指标 主 次 指标描述 最优水平组合 流动度 A>D>B>C 流动度越
大越好A1B1C1D1 漏失量 A>B>D>C 漏失量越
小越好A3B3C2D3 驻留长度 A>D>B>C 驻留长度
越长越好A1B1C3D1 封堵强度 A>D>B>C 封堵强度
越高越好A3B2C2D3 表 6 可酸溶凝胶复合堵漏剂的酸溶率
实验前
样重/g实验后烘干
残样重/g酸溶率/% 平均值/% 5.00 0.741 85.18 85.24 5.01 0.735 85.30 5.02 0.738 85.24 表 7 可酸溶凝胶复合堵漏浆对不同尺寸裂缝的封堵性能
裂缝/
mm驻留长
度/cmt封堵/
s正向承压
强度/MPa反向承压
强度/MPa0.1~1.0 3~4 25 12.3 6.5 1.0~2.0 7~10 33 10.5 6.1 2.0~3.0 9~12 39 9.1 5.2 注:堵漏浆为4%的膨润土浆+20%可酸溶凝胶复合堵漏剂 表 8 可酸溶凝胶复合堵漏浆对不同尺寸砂床的封堵性能
砂床/
目数侵入长度/
cm漏失量/
mL正向承压
强度/MPa反向承压
强度/MPa4~10 7~8 27 >15 7.5 10~20 5~6 17 >15 7.1 注:堵漏浆为4%的膨润土浆+10%可酸溶凝胶复合堵漏剂 -
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