深层碳酸盐岩储层酸压改造后的地质效果评价——以塔河油田缝洞型碳酸盐岩储层为例

深层碳酸盐岩储层酸压改造的目的就是让酸压裂缝与天然缝洞系统沟通。根据酸压改造施工曲线变化模式和酸压改造后的地质效果,提出了4类评价体系,每种体系对应一种酸压模式,包括未压开地层(Ⅰ类)、压开地层即行停止(Ⅱ类)、压开地层未与缝洞沟通(Ⅲ类)及压开地层并与缝洞沟通(Ⅳ类)的酸压模式。利用此方法对塔河油田27口井的酸压改造情况进行了分类评价,56%的井达到了Ⅳ类酸压模式,既压开了裂缝又实现了与天然缝洞系统的沟通,油井能保持较长期的高产稳产;22%的井达到了Ⅱ和Ⅲ类酸压模式;其余22%的井只达到了Ⅰ类酸压模式,此类油井的酸压效果有待进一步改善。该评价结果与油井实际产状具有较好的一致性。

Evaluation of geological effects of acid-fracturing in deep carbonate reservoirs:taking the fractured-vuggy carbonate reservoirs in Tahe oilfield as an example

Acid fracturing treatment of deep carbonate reservoirs is to establish communication between the fractures generated and natural fractures and vugs. Based on the variation modes of operating curves of acid fracturing treatment, and the geological effects of the treatment, 4 appraisal systems have been suggested each of which corresponds to one of the acid fracturing modes, including no fracture have been created (type Ⅰ), fractures have just been created and then stop (type Ⅱ), fracture have been created but have no communication with natural fractures and vugs (type Ⅲ), and fractures have been created and have communication with natural fractures and vugs (type Ⅳ). Acid fracturing treatments in 27 wells in Tahe oilfield have been categorized and evaluated with this method. Of these wells, 56% have reached the type Ⅳ acid fracturing mode and these wells can have high and stable productivities in a relatively long period; 22% are of type Ⅱ and Ⅲ; while the rest 22% are of type Ⅰ, and their acid fracturing effects need to be further improved. The evaluation results are in good agreement with the actual performance of the wells.