Introduction

IRRecent years, water-based drilling fluid has become a research hotspot in shale gas drilling fluid technology due to its advantages of safety, environmental protection and low cost. Due to the strong bedding rationality and low permeability, there are a large number of micro-fractures in the shale formation (the crack width is between 50nm and 40μm). Expansion and penetration will lead to the instability of the wellbore, which seriously restricts the popularization and application of water-based drilling fluids in shale gas production. Conventional plugging materials are distributed in the micron scale, which cannot effectively match the nano-scale micro-fractures of the shale formation, and it is difficult to achieve effective plugging, which leads to the occurrence of block loss and instability of the well wall during the drilling of shale gas horizontal wells. Therefore, it is of great significance to develop nano-scale plugging agents that match the shale formation and achieve effective plugging of nano-scale fractures to maintain wellbore stability and reduce the rate of complex downhole accidents.

During the drilling process, effective plugging of tiny cracks near the wellbore is one of the effective means to avoid the instability of the wellbore. To achieve effective plugging of nano-scale pores in mud shale formations, nano-scale plugging must be used. Material. At present, asphalt and emulsified paraffin plugging agents are commonly used in drilling engineering at home and abroad. These materials have large particle size and have better plugging effect on formations with large cracks and gaps, but cannot form a size with small cracks. If it is matched, a good inner mud cake cannot be formed, so the effective plugging of the micro-fracture formation cannot be achieved. Aiming at the problem that the pore size of the mud shale formation in Nanpu Oilfield is nano-micron, the traditional solid particles above micron are difficult to achieve effective plugging. The plugging agent can significantly improve the high temperature and high pressure filtration loss, the sand disc filtration loss and the pressure bearing capacity of the mud cake. The research results show that the drilling fluid with nano plugging agent can achieve high temperature and high pressure filtration loss of 17 mL and sand disc filtration loss of 14 mL, both of which are minimum values, and can effectively improve the pressure bearing capacity of the mud cake to greater than 9. MPa.

Performance Index:

Usage and dosage:

Usually the addition amount is 2~5%.

Package:

200 kg/drum