The $227 billion domestic crude oil tax has begun what is expected to be a long-winded but ultimately successful final passage through the Senate and then on to the president to be signed into law.

Purpose of the tax: to recoup part of the higher prices producers will receive as a result of President Carter's order last year gradually removing price controls from domestic oil.

Yesterday, Russell B. Long (D-La.), Senate Finance Committee chairman and a leading champion of oil producers, urged approval of the House-Senate conference report, which the House approved last week, as the price of decontrol. Decontrol has been held out by the industry as absolutely essential to getting more domestic production and making the United States less reliant on foreign oil.

But there will be a fight from some oil-state senators. Henry Bellmon (R-Okla.) will lead a drive to send the bill back to conference to get a better tax break for independent oil producers, who are in the production business only, and do most of the exploring for new oil. But Bellmon faces an uphill fight. Since the House has already approved the conference report, the conference committee has been dissolved and the only way to change the bill is to kill the report and ask for a new conference. Many senators would find it difficult to vote to kill the conference report and appear to be giving Big Oil a bonanza.