documentclass[11pt]{memoir}
usepackage[T1]{fontenc}
usepackage{lmodern}
usepackage{titlesec}
usepackage[version=0.96]{pgf}
usepackage{tikz}
usepackage{blindtext}
usetikzlibrary{arrows,shapes,snakes,
               automata,backgrounds,
               petri,topaths}               %To use diverse features from tikz

% Chapter style (taken and slightly modified from Lars Madsen Memoir Chapter
% Styles document
usepackage{calc,soul,fourier}
makeatletter
newlengthdlf@normtxtw
setlengthdlf@normtxtw{textwidth}
newsavebox{feline@chapter}
newcommandfeline@chapter@marker[1][4cm]{%
    sboxfeline@chapter{%
        resizebox{!}{#1}{fboxsep=1pt%
            colorbox{gray}{color{white}thechapter}%
        }}%
        rotatebox{90}{%
            resizebox{%
                heightof{usebox{feline@chapter}}+depthof{usebox{feline@chapter}}}%
            {!}{scshapeso@chapapp}}quad%
        raisebox{depthof{usebox{feline@chapter}}}{usebox{feline@chapter}}%
}
newcommandfeline@chm[1][4cm]{%
    sboxfeline@chapter{feline@chapter@marker[#1]}%
    makebox[0pt][c]{% aka rlap
        makebox[1cm][r]{useboxfeline@chapter}%
    }}
makechapterstyle{daleifmodif}{
    renewcommandchapnamefont{normalfontLargescshaperaggedleftso}
    renewcommandchaptitlefont{normalfontLargebfseriesscshape}
    renewcommandchapternamenum{} renewcommandprintchaptername{}
    renewcommandprintchapternum{nullhfillfeline@chm[2.5cm]par}
    renewcommandafterchapternum{parvskipmidchapskip}
    renewcommandprintchaptertitle[1]{color{gray}chaptitlefontraggedleft ##1par}
}
makeatother
chapterstyle{daleifmodif}
%
begin{document}
  blinddocument
end{document}