Expenditures for upstream represented 88 percent of the companywide total in The increase in earnings was largely due to higher margins on refined product sales. The increase in earnings was mainly due to higher natural gas sales volumes and prices partially offset by higher depreciation expenses from higher production volumes and an asset write-off.
Other unpredictable or unknown factors not discussed in this news release could also have material adverse effects on forward-looking statements. Refinery crude oil input in fourth quarter increased 10 percent tobarrels per day from the year-ago period, primarily due to the absence of turnarounds at the El Segundo, California refinery and the absence of impacts from Hurricane Nate at the Pascagoula, Mississippi refinery.
Demand for crude oil and its products and for natural gas is largely driven by the conditions of local, national and global economies, although weather patterns and taxation relative to other energy sources also play a significant part. Laws and governmental policies, particularly in the areas of taxation, energy and the environment, affect where and how companies conduct their operations and formulate their products and, in some cases, limit their profits directly.
The net liquids component of oil-equivalent production in fourth quarter increased 30 percent tobarrels per day, while net natural gas production increased 20 percent to 1.