Study On Adaptability Of Controlled Pressure And Water Release Technology In High Pressure Saline Layer In Kelasu Structural Belt

The Krassu structural belt is located in the northern part of the Kuqa depression in the Tarim Basin.It is about 220 km from east to west,30 km wide from north to south,and covers an area of about 3,500km2.It is the most abundant oil and gas area in the Tarim Basin and is the main battlefield for exploration and development in recent years.The geological conditions of the Krassu tectonic belt are very complicated.The Bashikiqik group of the Cretaceous is the main gas-bearing section.The upper part of the Kumgeri wood group generally has a thick salt layer,and the salt layer contains a set or Multiple sets of high-pressure salt water layers and weak layers mainly composed of shale and siltstone have narrow safety density windows,and leakage and spurt often occur during drilling.At present,although the pressure-control and water-discharging technology can effectively reduce the formation pressure of the high-pressure brine layer,widen the safety density window,and reduce the risk of complex accidents in the underground,the whole process technology is still in the initial exploration stage,lacking corresponding theoretical understanding and water release effect.The difference is great,the water release efficiency is not high,and the water discharge period is long.In view of this situation,this paper studies the applicability of the controlled pressure and water release technology of the salt water high pressure brine layer in the Krassu structural belt.Firstly,this paper investigated the drilling technology of high-pressure brine layer at home and abroad,and understands the current treatment methods of salt-to-salt highpressure brine layer,and statistics and summarized the distribution law of salt-salt layer and salt-to-salt high-pressure salt layer.Pointing out the problems in drilling in this block.Then,this paper establishes a controlled pressure and water discharge experimental device,and carries out indoor simulation experiments to analyze the effects of initial formation pressure,formation permeability,bottomhole pressure difference and wellhead back pressure on the water release effect.At the same time,the corresponding physical model is established for the water release process.The mathematical model explores the relationship between the vertical pressure,the casing pressure,the cumulative water discharge and the formation pressure during the pressure-controlled discharge process,and simulates the water discharge process of the Keshen A well.Finally,the main factors affecting the efficiency of water discharge are analyzed,and the evaluation method of whether the pressure-controlled water release technology is applicable is given.With the formation permeability,the original formation pressure,the increase of the bottomhole pressure difference and the decrease of the wellhead back pressure,the discharge rate and the formation pressure reduction rate are significantly increased,which is conducive to the implementation of pressure-controlled discharge,but the pressure reduction of the brine layer mainly depends on The cumulative amount of water released.By analyzing the non-drainage time and the ultimate casing pressure of the back pressure valve,it is the two main factors affecting the water discharge efficiency.When a well is suitable for pressure-controlled water release technology,it can be judged by using the method of trial-release water to avoid unnecessary economics in the oil field.loss.