Study On The Technology Of Fiber Suspension To Acidification In Horizontal Wells Of Fractured Carbonate Rock

Northeast Sichuan YuanBa Changxing group gas reservoirs is a deep marine carbonate gas reservoirs. Its ultra-deep (approximate7000m vertical depth), high temperature (about150℃), high content of H2S and other features such as most new wells are horizontal and deviated wells, coupled with the presence of natural fractures, makes strong heterogeneity between layers, causing uniform acidizing difficult. Therefore, making a reasonable distribution of acid fluid and reducing the costs and the risk of acidizing is the problem now to be solved.Through analyzing the reservoir geological characteristics, the difficulty of acidizing has been clear. This paper also optimized acidizing techniques and proposed fiber temporary plugging acidification technique to applied in target wells. Moreover, considering the actual situation of reservoir, this paper carried out a lot of laboratory experiments, studied many theoretical models, optimized the construction parameters and provided theoretical guidance for the acidizing, mainly carried out the following works:(1) Considering the actual situation of reservoir, the factors of fiber dispersed suspension have been studied by using dissolution method. Fiber degradation also has been studied. Moreover, this paper studied fiber plugging performance by using DL-2-type loss instrument for optimizing the length and concentration of fiber and proposed a theoretical formula of construction site fiber dosage.(2) The mechanism of fiber temporary plugging has been revealed, the fiber cake model has been established and the length and concentration of fiber has been optimizing by using basic parameters obtained from laboratory experiments. A horizontal well variable mass flow acid distribution model has been established. The influence factors of acid distribution, such as horizontal length, acid injection speed, acid viscosity has been analyzed. A fiber cake resistance model of skin factor has also been established. The effects of the fiber temporary plugging acidification has been analyzed by combined the two models.(3) Acidizing on site shows that the pressure rose significantly in temporary blocking phase, fibers temporary plugging turning effect is remarkable and yields improved significantly after acidification.The theoretical study and field application shows that fiber can greatly improve acid absorption profile of horizontal well. The technique is simple and easy to operate. This research provides a new idea for the ultra-deep, high temperature, high pressure and fractured carbonate horizontal well to exploit safety, economically and efficiently.