Study On The Law Of Decreasing Yield Of Gas Well In Shaxi Temple Gas Reservoir

Xinchang Shangshaximiao gas reservoir is that of a tight and low permeability and it belongs to the low permeable reserves,which are hard to exploit in present development sorts. Due to their low single layer deliverability and individual well producing rate, there is a major difference from conventional gas reservoirs in the production method and development model. In developing conventional gas reservoirs, we can use the method of drilling specified layer wells to enhance the gas reservoir deliverability by decreasing interlayer interference. But for in developing tight and low permeability gas reservoir, we can only use the method of multi-layer produce to satisfy the gas wells’industrial production. The filtration feature of low permeable gas reservoirs is different from that of conventional gas reservoirs, and its proration plan is also different. The analysis of production decline is seeking the law of production changes when oil and gas fields(wells) go into the decline stage, and predicting future production. By deep understanding of the law of production decline the main factors of production decline are analyzed and further effective measures are taken to slow the production decline in order to increase ultimate recovery, thus obtaining scientific and rational exploitation.Based on a large amount of literature research and analysis, this article has attained the affection of Shangximiao gas field flow characteristics to the gas wells deliverability, by analyzing the exprimental data of stress sensitivity and actuating pressure gradient. On the bass of conventional proration method, from the point of view of optimizing, according to the physical model of multi-layer producing gas wells and flowing from wellbore to the wellhead of the tight gas reservoirs, we have established a staged optimal production allocation mathmatic model and its solution, considering kinds of factors to the gas wells producibility. By analyzing, we have found the right way of stable time prediction and recovery in different proration. With the productivity decline law of different kinds gas wells and the research of numerical simulation, we have determined the key factors of affecting decline law and rate maintenance capability of gas wells, and proposed some development technology policies so as to decrease the gas reservoir decline.The research results indicate that:(1) stress sensitivity of low permeable gas reservoirs has a great affection to the gas wells deliverability, the stable time of different proration changes greatly. Adopting the stage rational proration method of this article, the pressure decline rate could be decreased and the gas reservoir’s stable time could be extended; (2) The decline law of Shangsha gas field is mainly index decline and hyperbolic decline. The key fators of affecting gas wells’stable production include the following points:①proration production;②single well controlling reserves;③measures used and construction parameters;④gas production rate;⑤well spacing pattern;⑥reservoir stress sensitivity(including closure of fracture). The development technology policies of slowing down the gas reservoir’s decline should be considered from these aspects.