The generator matrix

 1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  X  1  1  1
 0  X  0  0  0  X  X 4X  0 3X  X 6X 3X  X 2X 6X  0 6X  X  0
 0  0  X  0  0 5X 4X 5X  X 4X 5X 5X 5X 2X  0  X  X 4X 4X  0
 0  0  0  X  0 5X 3X 3X 5X 5X  X 6X  0 3X 4X  X  0 5X 5X 3X
 0  0  0  0  X 5X 6X  X 6X  X  X  0 3X 2X 5X 4X 3X 2X  X  X

generates a code of length 20 over Z7[X]/(X^2) who´s minimum homogenous weight is 91.

Homogenous weight enumerator: w(x)=1x^0+168x^91+936x^98+1584x^105+2616x^112+14406x^114+3816x^119+86436x^121+4428x^126+2520x^133+738x^140

The gray image is a linear code over GF(7) with n=140, k=6 and d=91.
This code was found by Heurico 1.16 in 3.17 seconds.