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川北阆中-南部地区大安寨段油气藏成藏模式以“自生自储”为主,总体上属于常温(74～80℃)、高压(原始地层压力系数>1.3)、构造-岩性复合圈闭、薄层状、低丰度、无边(底)水碳酸盐岩裂缝性未饱和油藏或凝析气藏。由于大部分油气井地层压力下降快,地层压力梯度低,产量递减率高,限制了常规酸化压裂等增产措施的推广应用。本文针对大安寨油气藏的地质特征,并结合油气藏开采效果评价,提出了采用胶凝压裂酸化(酸压)技术改造储层的增产措施。通过室内试验得到了凝胶酸TC4-1的配方:20%(HCl)+3.5%(CT1-9)+1.0%(CT1-3)+1.0%(CT1-7)+1.0%(CT5-9)+1.0%(IV-93)。针对不同类型的储层,对酸压工艺进行了优化,并实施了加液氮酸化、压前预处理等配套措施。现场实施效果表明,研制的酸化配方及配套技术具有良好的适应性和显著的增产效果。
The hydrocarbon accumulation pattern of Daanzhai section in Langzhong-southern area of northern Sichuan is dominated by “self-generative self-storage” and generally belongs to normal temperature (74-80 ℃), high pressure (original formation pressure coefficient> 1.3), tectonic- Trapped, thinly layered, low abundance, infill (bottom) carbonate fractured unsaturated reservoirs or condensate reservoirs. Since most of the oil and gas wells have a rapid decrease of formation pressure, low formation pressure gradient and high rate of decline of production, the promotion and application of stimulation measures such as conventional acid fracturing are limited. In view of the geologic characteristics of Da’Azhai oil and gas reservoir and the evaluation of the effect of oil and gas reservoir exploitation, this paper puts forward an increasing stimulation measures of using gelling fracturing and acidizing (acid pressure) technology to reform reservoirs. The formula of gel acid TC4-1 was obtained through laboratory experiments: 20% HCl + 3.5% CT1-9 + 1.0% CT1-3 + 1.0% CT1-7 + 1.0% ) + 1.0% (IV-93). For different types of reservoirs, the acid pressure process has been optimized, and the implementation of liquid nitrogen, pre-pressure pre-treatment and other ancillary measures. The implementation of the site shows that the acid formulation developed and supporting technology has good adaptability and significant yield increase.