There is a good article by Pepe Escobar on pipeline politics in Central Asia over at Alternet. I have included below only the excerpt that deals specifically with 9/11; however, the entire piece is a reminder that in terms of global pipeline politics 9/11 had to happen.

Pipeline-Istan: Everything You Need to Know About Oil, Gas, Russia, China, Iran, Afghanistan and Obama
By Pepe Escobar, Tomdispatch.com
Posted on May 13, 2009, Printed on May 13, 2009

Excerpt:

In August 1997, financially unstable Bridas sold 60% of its stock to Amoco, which merged the next year with British Petroleum. A key Amoco consultant happened to be that ubiquitous Eurasian player, former national security advisor Zbig Brzezinski, while another such luminary, Henry Kissinger, just happened to be a consultant for Unocal. BP-Amoco, already developing the Baku-Tblisi-Ceyhan (BTC) pipeline, now became the major player in what had already been dubbed the Trans-Afghan Pipeline or TAP. Inevitably, Unocal and BP-Amoco went to war and let the lawyers settle things in a Texas court, where, in October 1998 as the Clinton years drew to an end, BP-Amoco seemed to emerge with the upper hand.

Under newly elected president George W. Bush, however, Unocal snuck back into the game and, as early as January 2001, was cozying up to the Taliban yet again, this time supported by a star-studded governmental cast of characters, including Undersecretary of State Richard Armitage, himself a former Unocal lobbyist. The Taliban were duly invited back to Washington in March 2001 via Rahmatullah Hashimi, a top aide to "The Shadow," the movement's leader Mullah Omar.

Negotiations eventually broke down because of those pesky transit fees the Taliban demanded. Beware the Empire's fury. At a Group of Eight summit meeting in Genoa in July 2001, Western diplomats indicated that the Bush administration had decided to take the Taliban down before year's end. (Pakistani diplomats in Islamabad would later confirm this to me.) The attacks of September 11, 2001 just slightly accelerated the schedule. Nicknamed "the kebab seller" in Kabul, Hamid Karzai, a former CIA asset and Unocal representative, who had entertained visiting Taliban members at barbecues in Houston, was soon forced down Afghan throats as the country's new leader.

Among the first fruits of Donald Rumsfeld's bombing and invasion of Afghanistan in the fall of 2001 was the signing by Karzai, Pakistani President Musharraf and Turkmenistan's Nyazov of an agreement committing themselves to build TAP, and so was formally launched a Pipelineistan extension from Central to South Asia with brand USA stamped all over it.