You may use this awk:

awk '
/^Pattern1$/ {s = $0 ORS; next}
s != "" {s = s $0 ORS}
/^Pattern2$/ {printf "%s", s; s = ""}
' file

Pattern1
text7
text8
Pattern2
Pattern1
text15
text16
Pattern2
Pattern1
text7
text2
text8
Pattern2

$ awk '
/Pattern1/,/Pattern2/ {   # between the first start and end markers
    if(/Pattern1/)        # at the begin marker...
        b=$0              # ... reset buffer
    else 
        b=b ORS $0        # or keep on buffering
    if(/Pattern2/)        # at the end marker...
        print b           # ... it is time to output
}' file

head -4 of output:

Pattern1
text7
text8
Pattern2
...

Making a whole lot of assumptions about unstated requirements like whether to match to the first or last Pattern2, what to do if one or the other is missing from a file,what to do if both "patterns" occur on 1 line, etc.:

$ cat tst.awk
/Pattern1/ { f=1; rec="" }
f {
    rec = rec $0 ORS
    if ( /Pattern2/ ) {
        printf "%s", rec
        f = 0
    }
}

$ awk -f tst.awk file
Pattern1
text7
text8
Pattern2
Pattern1
text15
text16
Pattern2
Pattern1
text7
text2
text8
Pattern2

See also How do I find the text that matches a pattern?.