低成本致密油层水平井重复压裂新方法——以吐哈油田马56区块为例

吐哈油田马56区块致密油层水平井体积压裂后高产期短、一次采收率低，必须通过重复压裂提高产量，但常规重复压裂难以实现低油价下的水平井增产需求。为探索水平井低成本重复压裂新方法，通过分析区块前期生产特征，从提高采收率与体积压裂结合的方向出发，开展了岩心润湿、长岩心驱替、数值模拟以及注水现场试验等4项基础试验，验证大排量注水结合体积压裂工艺有助于恢复水平井产量，最终形成压前大排量注水蓄能（注入量为2倍采出量），再以高于初次压裂的排量进行全程滑溜水+小粒径支撑剂重复压裂，最后闷井5~15 d的重复压裂新方法。现场压裂试验取得成功，6井次压后平均日产油18.1 t/d，恢复到首次压裂产量77.4%；成本较首次压裂降低140万元/井次。该方法将笼统注水与重复压裂相结合，为致密油层水平井重复压裂探索出一条新途径。

A new low-cost refracturing method of horizontal well suitable for tight oil reservoirs: A case study on Ma 56 Block in Tuha Oilfield

When stimulated reservoir volume (SRV) of horizontal well is used in the tight oil reservoirs of Ma 56 Block in Tuha Oilfield, the high-yield period is short and the primary recovery factor is low, so it is necessary to increase the production rate by means of refracturing. However, the conventional fracturing can hardly satisfy the horizontal well stimulation requirement at low oil price. therefore, a new low-cost refracturing method of horizontal well was explored. Firstly, the previous production characteristics of Ma 56 Block were analyzed. Then, in order to combine EOR with SRV, 4 basic tests were conducted, i.e., core wettability test, long core test, numerical simulation and field water injection test. It is verified that the combination of high-rate water injection and SRV is beneficial to the production recovery of horizontal wells. Finally, a new refracturing method was developed. In this method, water is injected before SRV at high rate to store the energy (injection rate is 2 times of production rate), then slick-water+small-size proppant refracturing is carried out in the whole course at the rate higher than that during the initial fracturing, and finally well soaking is performed for 5-15 d. Its field fracturing test is successful. After 6 times' fracturing, the average daily oil production is 18.1 t/d, which is 77.4% of the oil production rate after the initial fracturing, and its cost is RMB1.4 million/well time lower than that of the initial fracturing. This method combines the commingled water injection with the refracturing, and it provides a new way for horizontal well refracturing of tight oil reservoirs.