Mar. 2013 - Anadarko announced it signed an agreement with an undisclosed party to enter into a carried interest arrangement for a portion of the company's ownership in the deepwater Heidelberg development in the US Gulf of Mexico. Under the agreement, Anadarko will be carried for $860 million, which represents nearly all of its expected capital requirements through first oil which is anticipated in mid-2016. In exchange, Anadarko will transfer a 12.75 percent working interest in the development. The company will continue as operator with a 31.5 percent interest. The agreement is subject to customary closing conditions but should close in April 2013. Heidelberg is estimated to contain 400 million barrels of recoverable resources.

Apr. 2012 - Anadarko has further appraised the Heidelberg discovery in the deepwater Gulf of Mexico after drilling two appraisal wells (GC 903-3 and GC 903-3ST1). The two wells were drilled in order to appraise the extension of the Heidelberg discovery made in 2009. The Heidelberg appraisal well GC 903-3 was drilled in a water depth of 5,260 feet (1,603 meters) and reached a total depth of 31,030 feet (9,460 meters) of measured depth. The well was sidetracked down dip (GC 903-3ST1 well) to a total depth of 30,440 feet (9,278 meters) of measured depth, indicating an oil water contact at approximately 700 feet (213 meters) deeper than the previous oil discovery well and significantly increasing the field's aerial extent. Estimated recoverable resources could reach 200 million barrels of oil. Data is being evaluated in order to accelerate the overall sanctioning process for this project.

Feb. 2012 - Anadarko Petroleum has successfully appraised the Heidelberg-2 appraisal well, located in Green Canyon Block 903 in the deepwater GOM. Heidelberg-2 encountered about 250 net feet (76 meters) of oil pay in high-quality Miocene sands. The appraisal well was drilled to a total depth of 31,030 feet (9,458 meters) in about 5,000 feet (1,524 meters) of water, about 1.5 miles (2.4 kilometers) south and 550 feet (168 meters) structurally updip from the Heidelberg discovery well. Log and pressure data from the appraisal and discovery wells indicate excellent quality, continuous and pressure-connected reservoirs with the same high-quality oil. Anadarko plans to immediately sidetrack the well to evaluate the down-dip extent of the field, and plans to initiate pre-FEED activities to prepare for sanctioning a development plan, stated the operator.

Oct. 2011 - Anadarko has commenced appraisal drilling on the Heidelberg No. 2R well in the Gulf of Mexico. The Discoverer Americas drillship is drilling the well on Green Canyon Block 903. An oil discovery was made on the field in 2009. Heidelberg is located on Green Canyon Block 903 in the Gulf of Mexico in a water depth of 5,276 feet (1,608 meters). Anadarko holds a 44.25 percent operating interest in Block 903.

Apr. 2010 - Anadarko will permanently plug and abandon the Heidelberg No. 2 well on Green Canyon Block 903 due to mechanical problems. The well did not reach the necessary depth to test the targeted objectives. Anadarko now plans to drill a substitute appraisal well using the ENSCO 8500 semisub, which is currently on location. The Heidelberg oil discovery is located on Green Canyon Block 903 in 5,276 feet (1,608 meters) of water. Anadarko holds a 44.25% operating interest in Block 859 and 903.

Jul. 2009 - The ENSCO 8500 semisub rig is slated to drill another well at the Heidelberg discovery around mid-September 2009. Heidelberg was discovered in February 2009 on Green Canyon Block 859 encountering more than 200 feet (61 meters) of net oil pay in several high-quality Miocene sands. Anadarko is the operator of this discovery and holds a 44.25% interest. Other partners in the discovery are ENI 12.5%, Mariner 12.5%, StatoilHydro 12%, Cobalt 9.375% and ExxonMobil 9.375%.

Jun. 2009 - Anadarko submitted a Supplemental Exploration plan for the Heidelburg field. Heidelburg covers Green Canyon Blocks 816, 859, 860 and 903 in a water depth of 5,274 feet (1,608 meters). The plan proposes to drill and complete three wells, GB859 location E and GB903 locations A and C. Anadarko is the operator and holds a 44.25% interest in the field. Other partners are Eni (12.5%), Mariner (12.5%), StatoilHydro (12%), Cobalt (9.37%) and ExxonMobil (9.37%).

Mar. 2009 - The Heidelberg discovery, located at Green Canyon 859, is scheduled for appraisal drilling in the 2nd half of 2009. Mariner reported in the company's 4th quarter earnings call that they expect an appraisal well will be spud later in 2009. Anadarko is the operator of Heidelberg and holds a 25.5% interest in the discovery.

Feb. 2009 - Anadarko Petroleum Corporation (NYSE:APC) today announced a substantial oil discovery at its Heidelberg prospect in Green Canyon block 859 in the deepwater Gulf of Mexico. The discovery well encountered more than 200 feet of net oil pay in several high-quality Miocene sands.

Jun. 2008 - Mariner has farmed into the Heidelberg subsalt prospect with a 12.5% interest. An exploration well is expected to spud by year-end 2008.