缝洞型碳酸盐岩油藏基质低孔低渗,基本无储油气能力,缝洞为主要储渗空间,但缝洞体空间发育复杂、连通性差,单井钻遇缝洞规模有限。针对常规注水和酸压无法实现远井区高效扩容,导致单井初产高、递减快、采出程度低,开展了高压注水扩容工艺现场试验,以高压注入水为能量载体,突破孤立缝洞体屏障,实现有效扩容。该工艺在塔河S1井现场试验效果显著,该井前期实施常规注水替油3轮次,效果逐渐变差,生产表现为定容体特征。地震显示井周缝洞体规模大,开展了2轮次高压注水扩容试验,累计注水2.98×10 ⁴m ³,最大注水压力23 MPa。注水曲线表明,高压注水沟通井周2套缝洞系统,改善了该井的生产状态,周期含水率由45 %降至4 %,生产压降由29 MPa降至26 MPa,单位压降产液量由201m ³/MPa增至547m ³/MPa。截至目前,已累计增油14 721 t。试验表明,高压注水扩容工艺可以实现定容缝洞型碳酸盐岩井的有效扩容,增加单井产量和储量,同时可为降低近井油水界面创造空间条件,延长单井无水采油期。

The fractured-vuggy carbonate reservoirs with low porosity and low permeability basically have no oil and gas storage capacity. Fractures and caves are the main storage and permeability spaces, but fractures and caves have complex developed space and poor connectivity. Due to the limited sizes of fractures and caves during drilling in single well, and the failure of conventional water injection and acid fracturing reforms to achieve efficient expansion in remote well areas, single well production has high initial production, rapid decline, and low production. Therefore, a field test of the high-pressure water injection volume expansion process was carried out, that is, using high-pressure water injection as an energy carrier to break through the barrier of an isolated fractured-vuggy system and achieve effective expansion. This process was tested in the well-S1 of Tahe Oilfield, and the effect was significant. The well was subjected to conventional water injection and oil replacement for 3 rounds in the early stage, and the effect gradually became worse. The production is characterized by constant volume. The seismic data show large-scale of the fractured-vuggy system around the well. Two rounds of high-pressure water expansion test are carried out, with the cumulative water injection of 2.98×10 ⁴ m ³ and maximum injection pressure of 23 MPa. The water injection curves show that the high-pressure water injection make two fractured-vuggy systems around one well communicate with each other, improving the production status of this well. The cycle water content is reduced from 45 % to 4 %, and the production pressure drop is reduced from 29 MPa to 26 MPa. The production volume per unit pressure drop increased from 201 m ³/MPa to 547 m ³/MPa. So far, the cumulative oil increase has been 14 721 t. The tests show that the high-pressure water injection expansion technology can achieve the effective expansion of fractured-cavity carbonate wells with constant-volume, increase single-well production and reserves, and at the same time, create space for reducing the oil-water interface near the well, so as to extend the dry oil recovery period.