On a sequential quarterly basis, prices were about flat for worldwide oil, down 4 percent for NGLs and up 24 percent for domestic natural gas. Domestic realized oil prices increased by about 4 percent while Middle East/North Africa prices decreased by about 5 percent, collectively resulting in flat prices worldwide.
Chemical
Chemical core earnings for the second quarter of 2013, after exclusion of the $131 million pre-tax gain from the sale of the investment in Carbocloro, were $144 million, compared with $194 million in the second quarter of 2012. The lower earnings resulted from lower caustic soda export volumes due to continued weak economic conditions in Europe and slowing demand in Asia, particularly within the pulp and paper and alumina segments; reduced alumina demand in South America; continued weak export chlorinated organics pricing resulting from new organics production in Asia; and higher energy and feedstock costs.
Midstream, Marketing and Other
Midstream segment earnings were $48 million for the second quarter of 2013, compared with $77 million for the second quarter of 2012. The decrease in earnings was caused by lower marketing and trading performance.
SIX-MONTH RESULTS
Net income for the first six months of 2013 was $2.7 billion ($3.32 per diluted share), compared with $2.9 billion ($3.55 per diluted share) for the same period in 2012. Year-to-date 2013 core income was $2.6 billion ($3.27 per diluted share), compared with $2.9 billion ($3.56 per diluted share) for the same period in 2012.
Oil and Gas
Oil and gas segment earnings were $4.0 billion for the six months of 2013, compared with $4.5 billion for the same period of 2012. The $500 million decrease reflected lower worldwide oil and NGL prices and higher DD&A rates, partially offset by higher domestic gas prices and lower operating costs.
Oil and gas production volumes for the six months were 768,000 BOE per day for 2013, compared with 760,000 BOE per day for the 2012 period. Year-over-year, our domestic production increased by about 3.5 percent or 16,000 BOE per day. In the second quarter of 2013, volumes were negatively impacted by severe storms in West Texas and the planned turnarounds in the Permian. International production was 8,000 BOE per day lower due to a first quarter 2013 planned maintenance turnaround in Qatar, the impact of full cost recovery at our Dolphin operations and higher insurgent activity in Colombia. Daily sales volumes were 755,000 BOE in the first six months of 2013, compared with