双水平井SAGD间歇式吞吐强化扩腔技术

强非均质储层条件下，超稠油双水平井SAGD开发中普遍存在注采井间窜扰、水平段动用不均匀、蒸汽腔规模小且扩展缓慢等问题，导致SAGD井组长期处于低产、低效状态。为了改善开发效果，提出双水平井SAGD间歇式吞吐强化扩腔技术策略。以新疆风城油田M区实际井组为例，采用数值模拟对吞吐操作方式、注采参数、转轮时机等关键参数开展了系统研究。研究结果表明，采用注汽井注汽(生产井关井)，焖井后生产井采油(注汽井关井)的方式，在合理注采参数条件下，间歇式吞吐能有效改善开发效果，采收率达53.8%。SAGD间歇式吞吐强化扩腔技术主要作用机理为:(1)吞吐期间注汽井高速注入，蒸汽热损失减少；(2)注汽时消除了汽窜和压差影响，有助于扩大蒸汽波及和动用较差区域；(3)注汽期间重力泄油持续进行，建立的液面在开井生产时能有效防止汽窜，实现高效泄油。采用该技术在风城M区开展了2井组试验，措施后日产油水平提高了1.5 t/d，且生产稳定，研究成果为同类油藏改善开发效果提供技术参考。

Reinforced expansion of dual-horizontal-well SAGD steam chamber: An intermittent huff-and-puff approach

In highly heterogeneous ultra-heavy oil reservoirs, the dual-horizontal-well SAGD commonly suffers from interference between injection and production wells, uniform production profile of the horizontal wellbore and a small steam chamber with slow expansion, which leads to long-term low production and low efficiency of SAGD well groups. To improve the recovery performance, this research proposed a reinforced SAGD steam chamber expansion technology for dual horizontal wells, based on the intermittent huff-and-puff operation. A case study of numerical simulation was performed for the M block of the Xinjiang Fengcheng oilfield to systematically investigate key parameters, such as the huff-and-puff operation scheme, injection-production parameters and operation switch timing. The results showed that with proper injection-production parameters, the recovery performance can be effectively improved by the intermittent huff-and-puff, in which the steam is injected into the steam injection well (with the production well being shut in) and the production well starts to produce (with the injection well being shut in) after some time of steam soaking; the resultant recovery factor reaches 53.8%. The mechanisms of this technology are as follows: (1) high-rate injection of steam during the huff operation reduces the heat loss of steam; (2) the effects of steam channeling and formation pressure difference are eliminated for steam injection, which helps steam to sweep the insufficiently-recovered zone; and (3) gravity drainage continuous to work during steam injection and the resultant liquid level in the production well can effectively prevent steam channeling during production and facilitate high-efficiency oil drainage. The field testing of this well has been performed in two well groups of the M block, the Fengcheng oilfield. The resultant production is stable, with an increment of daily oil production of 1.5 t/d. The research results provide references for improving the recovery performance of analogous oil reservoirs.