Abstract

Magnetic technology has been widely used in oil fields and other aspects due to its many outstanding advantages. Yet its main utilization lies in oil production and transportation, and little research is done on the magnetized drilling fluid. In this paper, through experiment, it is shown that magnetization can apparently reduce the viscosity and improve the inhibition ability of the mud system.

Introduction

The magnetic technology was first put into use in FSU (Former Soviet Union), used to avoid the scale formation in production well. In China P.R., this technology was first successfully used in wax avoidance in 1985 in Daqing oil field, the biggest oil field of china. From then on, for the outstanding advantages of the magnetic technology, such as easy installation, no power consumption, cost effectiveness, no pollution and excellent effect, its applications have been developed in water flooding enhancement, wax inhibition, scale inhibition, oil viscosity reduction, oil solidifying point reduction and so on. And for the success of this technology in the oil production system, more than 200 million RMB (currency of china) has been obtained1.

However, the research on magnetized mud is still vacant. In this paper, the properties of the magnetized mud are tested.

Test Equipment, Method and Muds

Test Equipment.

The test equipment is a simple circulation system. In the experiment, a liquid pump is used to stimulate the circulation. An adjustable magnetizer is used, whose capacity isfrom 0 mT to 1000 mT. And a flow rate measurer is introduced to stabilize the circulation at the required flow-rate.

Test Method.

Adjust the magnetizer at different intensity to observe the effect of intensity on the properties of the muds. Maintain the circulation under certain magnetic intensity for 12 hours, then get the mud to be tested on its appearance viscosity and shale recovery. Adjust the pump to stabilize the flow rate at about 400 gal/min, which is a frequently employed flow-rate while drilling mid-deep wells.

Test Mud.

In the tests, four muds of different composition are used. Their compositions and properties are listed respectively in Table 1 and Table 2.

Purposes and Challenges of the Research

During the development of drilling fluid, many chemicals have been developed to make the drilling fluid system meet certain requirement. Yet little work has been done on the usage of physical methods to improve the properties of the drilling fluid.

Among all the properties, viscosity and inhibition are two most important factors that directly influence the quantities of the drilling work. With the increases of the viscosity, the drilling rate severely drops down. On the other hand, wellbore instability is another troublesome problem, which greatly raises the drilling cost. As a result, large amounts of thinners (dispersants) and shale inhibitors have to be added to the system. What's more, high percentage of these additives are not only expensive, but also not easily biodegradable, such as the cationic copolymers that serve as shale inhibitors2. The even worse is that the biodegradation of the additives are not always so emphasized like the effect and the price of the additives, especially in some developing countries.

Whether the properties of the drilling fluid can be changed under magnetic field is the purpose of this research. Compared with the success that magnetic technology has achieved in the field of oil production, will magnetized mud be so effective and economical?

Test Equipment.

The test equipment is a simple circulation system. In the experiment, a liquid pump is used to stimulate the circulation. An adjustable magnetizer is used, whose capacity isfrom 0 mT to 1000 mT. And a flow rate measurer is introduced to stabilize the circulation at the required flow-rate.

Test Method.

Adjust the magnetizer at different intensity to observe the effect of intensity on the properties of the muds. Maintain the circulation under certain magnetic intensity for 12 hours, then get the mud to be tested on its appearance viscosity and shale recovery. Adjust the pump to stabilize the flow rate at about 400 gal/min, which is a frequently employed flow-rate while drilling mid-deep wells.

Test Mud.

In the tests, four muds of different composition are used. Their compositions and properties are listed respectively in Table 1 and Table 2.

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