Evaluation and Research of Determining Gas Well Deliverability Method by Using Non-stabilized Well Test

The productivity of oil and gas well plays an important role in oil and gas field development, being a basis of design oil and gas field development plan and reasonable proration. Nowadays, the main method of determining oil and gas well deliverability is steady well test, that is back - pressure testing,isochronal testing, revisionary isochron test and single - point test. The demerit of these methods is long testing time. However, using non - stabilized well test method to determine the productivity of gas well, greatly improves the efficiency and economic benefit of assessing productivity. In the text, the theoretical basis and actual meaning of using three non - stabilized well test methods to determine the productivity of gas well are discussed. Meanwhile, its calculation precision and applicable condition, advantage and disadvantage, the inherent relation with some different methods, common point and different point are analysed. Based on these a new method that pressure build - up curve associated with pressure fall - off curve to determining the productivity of gas well is proposed. The calculation example shows that feasibility of this method and reliability of accuracy.