As a soon-to-be graduate of %%it courses name here%%, I am passionate about web technology and eager to use my skills as a web developer. A career at %%Company's name%% appeals to me because (list 1-3 things that will benefit the company Example: The company's website says that they value a team-oriented environment and that they love to make websites for old people. so say "appeals to me because I value a collaborative work environment where I can assist the elderly to operate their own websites).
I think that you could remove the petroleum engineering background from your cover letter. It's not relevant to web developer and they can see that in your resume. I changed the order to "graduate of...." because it sounds more formal in this way (It's hard to explain why if you don't understand and the difference is minor). I removed excited because it is redundant. Passionate is an excellent descriptor and you do not require more language to describe this. For the part about success, it sounds too focused on you and not focused enough on the company. I don't know the company, but you might be better off starting that part of the sentence by talking about how you will help the company. My suggestion is above.
Sorry if my answer is messy. Just trying to give more explanation so that you understand my reasoning. Do not forget that for your information technology classes, you need to make that if you use my change, that you change your noun to fit the grammar.
Good luck.