Session: 11-05-02 Well Cementing Theory & Practice-2

Paper Number: 79424

79424 - Jet Cleaning Processes in the Plug and Abandonment of Oil and Gas Wells: An Experimental Study on Horizontal Miscible Jets 

The plug and abandonment (P&A) operation is considered as one of the essential stages during the life cycle of oil and gas wells. One of the main objectives of the P&A operation is to ensure that the abandoned oil or gas well is completely secured from any fluid’s movement, with no leakage from the hydrocarbon zone to other formations/layers. In general, each well needs to go through specified steps during the P&A operation; these may include accessing behind the casing (i.e. annulus), cleaning the target area, and installing the cement plug barriers in the target area. To avoid cement contamination and ensure a good bond between the cement and casing, the inside and outside the casing should be properly cleaned, using available industrial techniques. The jetting process is one of the efficient approaches in the cleaning step of the P&A operation, where an injection fluid pushes, removes and cleans unwanted fluids/materials. The cleaning efficiency of the jetting process is affected by different parameters, such as fluid properties (e.g. rheological parameters of the injection fluid and the ambient one and the density/viscosity difference between them) and the geometrical parameters (e.g. well inclination, nozzle-casing distance, ratio of nozzle and perforation diameters, etc.). To achieve an efficient jet cleaning process, studies on the effects of these parameters seem crucial.

 

In this paper, we experimentally study the characteristics of horizontal miscible jets, to develop an understanding about the fundamental aspects of the jet cleaning process in the P&A operation. In this work, a fluid is injected horizontally into a large tank filled with a miscible ambient fluid. To properly transform the real case to the laboratory scale, a perforated wall is considered between the injection nozzle and the tank wall, representing the perforated casing between jetting tools and formation walls. We analyze the effects of different parameters on our horizontal jet behavior, including, the injection velocity, the perforation diameter, and the rheological parameters of the ambient fluid. We identify the jet behavior using different characteristics, such as the laminar length (i.e. the stable cylindrical part of the jet where the jet fluid does not mix with the ambient fluid), the mixing index (i.e. the degree of mixing between the jet and ambient fluids), and the jet radius. Based on our results, increasing the injection velocity leads to a decrease in the laminar length. Also, the mixing index before the perforated wall increases by decreasing the perforation diameter. In addition, using the non-Newtonian ambient fluid results in decreasing the jet radius at a certain axial position.

Presenting Author: Hossein Hassanzadeh Laval University

Authors:

Hossein Hassanzadeh Laval University
Elliott Cournoyer Laval University
Seyed Mohammad Taghavi Laval University