| With the deep well drilling work, drilling fluid technology under deep well and high temperature has been development. The need for drilling fluid under deep well is a new kind of drilling fluid system and matching techniques different from the shallow well. The technology of drilling fluid above 200℃ especially 220℃ is an urgent problem. Foreign workers use oil based drilling fluid were motivated by it’s good temperature stability, inhabitive property and low filtration, but we consider to use water based drilling fluid for low cost and environment friendly. The major different problem of ultra-temperature drilling fluid is control over rheology property and filtration, as well as the key technology is the colloidal stability. Along with the geological condition is very complex, the properties of drilling will be more difficult to control when there are both high temperature, high salinity and so on. To ensure the safety and quickly drilling job, we need to establish drilling fluid system which has good temperature-tolerance under ultra-high temperature. The rheological model study is also an essential part of drilling engineering, it can provide reference for rheological paremeters.This research focus on the sub-topic of the research foucus on optimization and application of high temperature resistant water based drilling fluid:drilling fluid system designof Well Songke 2. According to the information of wells in adjacent area and geothermal gradient, the bottom hole temperature of well Songke2 above 240℃. it is necessary to set up a ultra-high temperature drilling fluid system to meet the requirements of project. This paper discussed the control mechanism of water-base drilling fluid on the base of analysis the effect of high temperature on drilling fluid. Develop a high-temperature stabilizing agent and a filtrate loss reducer, then bulid a drilling fluid formula. Based on this formula sutdy it’s rheological mathermatical model.This article first provides an overview of high temperature resistant treatment agent and drilling fluid,look at the problem of them. Then briefly covered the impact of high temperature on caly, treatment agent and properties of drilling fluid, discuss the control mechanism include rechological control and filitration control and so on on this basis.Tacking the clay into consideration, develop a new kind of treatment which named MG-H2 that can improve the way act on clay through inverse emulsion polymerization method. MG-H2 can be used as a fluid flow pattern regulator and high-temperature stabilizing agent, it can enter the space structure of clay particles to reduce the ragid connection of them and weaken temperature influence on drilling fluid properties, then matain the rhelogical of drilling fluid. Design molecular structure based on the features and requriments of temperature resisting and salt tolerance polymer treatment, Select monomer and consider reaction temperature, initiator addition, monomer concentration, reaction time, pH impact on it. then develop a filitration control agent named AADS. Analysis their structure by FTIR, confirmed the molecule and diameter of MG-H2 through scanning electron microscope, TEM and particle size analyser. Evaluate it’s effect in fluid we can find the rechological is well and have less HTHP filitration. Analysis the temperature torence of AADS through TG-DTA, mesure the intrinsic viscosity with ubbelohde viscometer then know the relative molecular weight. AADS showed less of an effect of rheological behavior and have better ability resistance the salts.Use MG-H2 and AADS as key treatment agent, selet other agents such as assist filitration reducer. In addition, add some attapulgite, seltion a appropriate proportion. According the drilling design paremeter of well CCSD-SK2, build a water-base drilling fluid formula that can resist temperature of 240℃. Evaluation the overall performance of drilling fluid, the results show that it has good temperature resistence, strong resiatance to calcium and salt,better inhibitor and lubricity property.Finally, Mainly consider temperature infect on properties of drilling fluid. Mesure the rheological parameter under shear rate 3rpm、6rpm、100rpm、200rpm、300rpm and 600rpm and temperature from 60～240℃ by Farm 50SL. Combine conventional rheological model and function, introduce Temperature factor to HB model and established a high temperature rheological model. The unltra-high temperature 240℃ drilling fluid technique will lay the foundation for further 260℃ drilling fluid syetem, it can provide the technical support to safety and successfully drilling and have wide application foreground. |
