不同開發方式下礁灰巖油藏驅油效率研究

王亞會 閆正和 張曉林

摘 ? ? ?要：南海東部礁灰巖油田具有儲量開采程度低、裂縫發育復雜、非均質性強等特點，優化開發方式是提高開采效果的有效途徑。以南海東部裂縫性中高滲礁灰巖L油田為例，選取目的層段的4塊全直徑密閉巖心，拼接成直徑10 cm，長度30 cm的長巖心組，在實際油藏條件下，模擬頂部注氣、底部注水、底部注水驅至殘余油后轉頂部注氣和底部高含水轉注氣段塞驅等實驗，深入分析影響不同驅替方式下開采效果變化原因。結果表明：①頂部注氣0.78 HCPV時，注入氣處于臨界突破點，大量形成油、氣互溶混相驅，凝析混相驅和重力穩定驅效果明顯，驅油效率高達70.7%，注入氣突破臨界點后，入口壓力下降，驅油效率趨于穩定;②底部注水量從0到0.37 HCPV，驅油效率增長較快，最高僅為43.3%，較頂部注氣效果差;③底水驅油后，不論頂部注氣或底部注氣段塞驅，滲流優勢通道中氣水混合流動均易形成賈敏效應，波及范圍變大，隨著注氣倍數增加，驅油效率可提高3.0%～6.4%。該研究成果可為裂縫性中高滲礁灰巖油藏合理高效開采開發提供技術支持。。

關 ?鍵 ?詞：全直徑巖心;裂縫性高滲;礁灰巖;開發方式;驅油效率

中圖分類號：TE327 ? ? ? 文獻標識碼： A ? ? ? 文章編號： 1671-0460（2020）05-0821-05

Abstract： The reef limestone in the eastern South China Sea has the characteristics of low recovery， complex fracture development and strong heterogeneity. Therefore， optimizing the development mode is the key factor in determining the exploitation results. In this paper， L reef limestone reservoir in the eastern South China Sea was set as the target reservoir， and a long core set （diameter 10 cm and length 30 cm） consisting of 4 full diameter cores was selected from this reservoir. Crestal gas injection experiments， bottom water flooding experiments， experiments by converting bottom water flooding to crestal gas injection and experiments by converting bottom water flooding to gas slug injection were carried out，and the results of different development modes were analyzed. The results showed that ① When 0.78 HCPV gas was injected from the top， the injected gas reached the critical breakthrough point and the oil-gas miscible flooding statement was achieved. Condensing miscible flooding and gravity stable flooding were effective in this stage and the displacement efficiency reached 70.7%. After the injected gas broke through， the inlet pressure declined and the oil displacement efficiency tended to be stable. ② When bottom water was injected from 0 to 0.37 HCPV， the oil displacement efficiency increased rapidly but the final oil displacement efficiency was only 43.3%， which was lower than that of the crestal gas injection. ③ After the bottom water flooding， the gas-water mixture tended to cause the Jamin effect and the scope of sweeping was enlarged. With the increase of injection pore volume multiple， the oil displacement efficiency increased by 3.0%～6.4%. These experiments can give base data and technical support for the development of fractured reef limestone reservoirs.

Key words： Full diameter cores; High permeability with fracture; Reef limestone; Development modes; Oil displacement efficiency