Study And Application Of Stimulatiing Technology On Deep Fractured Reservoir With Complex Lithology In Qingxi Oil Field

The average buried depth of Xiagou group in the major reservoir of Qingxi oil field is at about 4500m.The reservoir lithology is complex,carbonatite,clasolite(quartz and feldspar) and clay mineral content are different from conventional carbonatite and sandstone,the mineral composition of rock is complex,the matrix porosity and permeability of the rock core are considerably low,the permeability of the untracked rock core is hard to measure.It is difficult to explore such fault block oil reservoir which have characters of high temperature,high voltage,low porosity and low permeability.Because of the reservoir lithology and mineral composition change too fast the corresponding layers of each well are different,furthermore the lithologies are mutual conductance on the profile of the same well.The water-sensitive and stress sesitivity conditions are strong,the natural fracture is prone to be polluted in the process of drilling and completion.Meanwhile some extent of mineral such as pyrite,siderite and calcite which will decline the connectivity conditions of fractures are existing in the natural fracture.The worse thing is that it will forms some isolation apertures which only could be reformed by fracture acidizing to release the fracture polluting and improve the conductivity of network of fracture. But the conventional acidification and acidizing fluid are not suit to the Qingxi fractured reservoir.According to the requirement of production of exploration,we have to study the enhanced recovery techinique aimed at this kind of reservoir.This paper do some research on the key fracturing technology of Qingxi deep complex lithology fractured reservoir and get the fruits as follows.1.Analyse a lot of data such as indoor test result and,a comprehensive recognition of engineering geology characteristic and present the technology difficulties and requirements of reservoir engineering geology to acid fracturing.2.On the basis of analysis of rock core observation and imaging well-log information, get the log response characteristics of corrosion holes,horizontal fracture and high angle fracture,present the recognition technology of the horizontal open fracture,potential horizontal fracture and bedding plane,establish recognition technology of the effective reservoir of argillaceous dolomite fractured reservoir,calculate fracture porosity and permeability according to conventinal log data and interpret the 13 wells.3.Test the mechanical properties of dolomitic mudstone,argillaceous dolomite and conglomerate aiming at the specific rock type of Qingxi oil field,get the related mechanical parameters which provide data base for fracture acidizing design.4.Finding the stress direction of Qingxi oil field according to the analysis of viscous remanent magnetization,the restoration of thermal elastic strain,borehole avalanche and drilling-induced fracture.Study the value of stress on the basis of test of stress value, characteristics of borehole avalanche,data of fracture acidizing.Obtain integrated styloid profile using the measured data to correct and calculate the value on the basis of get parameter by the interpreting of well-log information.5.By considering the combined influences to crack propagation form the influential factors such as pressure drawdown alone the fracture,fluid gravity,crustal stress gradient, stress contrast and so on,built the triaxial fracture extension model to simulate the dynamical fracture extension during the acid fracturing,at the same time by considering the acid longitudinal mass transfer,built the triaxial acid flowing reaction model which can simulate the alteration of acid concentration by the change of length,width,height and orientation of fracture and has a better performance in accommodation.6.Aiming at HTHP complex lithology fault block oil reservoir of Qingxi oil field, develop combination of acidizing fluid system which is organic synthetised by Gelled acid and emulsified acid,this kind of system is helpful to Qingxi oil field.7.Through acid rock conductivity experiments,has accessed adaptability of several major acid system and the process of acid pressure for the lithology of Qingxi oil field,then the type of acid and acid fracturing process model which aimed at the lithology have been proposed; underground construction tools and string combination Which adapt to acid and facture in deep well of Qingxi oil field has been Studied successfully,the supporting measures better meet the needs of the deep well and high-temperature reservoir acid fracutre.8.Through practice for years,the seven kinds of typical acid pressure technology modes that aimed at the formation of a different lithology and different degree of fracture are built up and have been applied successfully in the field,have achieved remarkable economic and social benefits.The technologies have made good help to add the production of Qingxi oil field.