- 期刊
油氣採收技術探討－油管尺寸評估
The Study of Developing Techniques-Optimum Tubing Size Selection for a Gas Field
摘要
本研究利用氣井液體聚積評估方法、節點分析理論及物質平衡桶狀預測模式，篩選油氣採收之最佳油管尺寸，研究結果顯示，氣田於生產早期（氣層靜壓大於6000 Psig），在最低井口流壓1250 psig之限制下，採3－1/2＂油管生產，產率可達1000 mscm/d以上，在氣層靜壓高於4000 psig狀況下，亦可輕易地提供500 mscm/d天然氣之要求。此外採3－1/2＂油管生產時，在中水驅型氣田（Rr=5）、弱水驅型氣田（Rr=2）及耗竭型氣田三種氣田型式中，以中水驅型氣田穩產500 mscm/d之時間最長，但總生產年限則以耗竭型氣田最長，三者平均採收率為71%。採4－1/2＂油管生產時，亦以中水驅型氣田穩產1000 mscm/d之時間最長，總生產年限則以耗竭型氣田最長，平均採收率則為69%。總而言之，未來生產單位針對C地塊氣田生產井若有較大天然氣產量之需求（如長時間產率需達1000 mscm/d），則生產井採4－1/2＂油管應較符合要求；但若未來生產單位對氣井產量設計之需求量不高（如長時間產率低於500 mscm/d，尖峰短時間需達600～1000 mscm/d），則3－1/2＂油管已足以達到要求，無需採用4－1/2＂油管，如此除了可以避免生產末期採大油管較易液體聚積壓死氣井外，並可提高整體氣田油氣之採收率。
並列摘要
The optimum tubing size is screened by the technique of liquid loading up in gas well, nodal analysis, and material balance calculations. Based on our results, using the 3-113＂ tubing can reach the rate of 1000 mscm/d in the early production time, which the reservoir pressure is 6000 psig and minimum wellhead pressure is 1250 psig. After the field pressure drops to 4000 psig, using the 3-1/3＂ tubing still can produce at the rate of 500 mscm/d easily, Assuming a water influx is a driving force for this field, two cases with moderate (Rr=5) and weak (Rr=2) water drive and depletion type were considered. Average recovery factor is 71%. Moderate water driving case maintain plateau production rate (500 mscm/d) longest. The depletion type case has the longest total production life. If 4-1/2＂ tubing is used, similar trend was observed and average recovery factor is 69%. In summary, one can use 4-1/2＂ tubing to obtain large production rate, especially a rate of 1000 mscm/ d is required for a long period. If the production rate of 500 mscm/d is common production rate and the rate between 600 to 1000 mscm/d is produced in a short time, 3-1/2＂ tubing can be considered as an optimum size of tubing due to lower liquid load up rate and higher recovery factor.