Research on Water-Based Drilling Fluid for Super Depth and Ultra-High-Temperature Horizontal Wells in Tarim Basin

Abstract

One area of northern Tarim Basin in China is carbonate reservoir, and the reservoir is between 6600 ~ 6900 m. The bottom hole static temperature is close to 170°C, the ECD of pore pressure is 1.1 ~ 1.15 g/cm3. In order to improve the development economic benefit, reservoir need to adopt horizontal well development. Water-based drilling fluid is required to resistant high temperatures and high salt, prevent leakage of limestone reservoir fracture, control the density, protect the reservoir from damage, and has good rheological properties. For old poly-sulfide drilling fluid system, through the indoor evaluation system of various treatment agent and temperature resistance, authors found that by using polymer viscosities, loss of water and temperature resistance of lubricant can reach 140°C. Therefore authors developed the temperature stability agent and high temperature resistant lubricants. This paper introduces the mechanism of the treatment, and evaluates the performance of synthetic products. Aiming at the shortage of the lubricant, authors develop a blister, crosslinking, good environmental protection and maintain water-based lubricant characteristics of resistance to high temperature lubricant. It has good environmental protection ability. Through the evaluation, it has good lubricity and temperature resistance. By introducing the resistance temperature resistance to high temperature drilling fluid system, and after the application in well H9-10H, new drilling fluid system was carried out, well meet the requirements of drilling engineering.