Last week, the U.S. Department of Interior announced a temporary suspension of delegated authority for 60 days.
We've also seen, in the past two weeks, over 20 approvals given for work in the Gulf of Mexico to not only us, but our peers.
Slide 4, Murphy produced an average of 149,000 barrels of oil equivalent to-date -- per day in the fourth quarter.
These volumes include impacts totaling nearly 4,000 barrels equivalent from two subsea equipment issues with production expected to restart in the first quarter 2021.
Our cash capex totaled $111 million for the quarter, inclusive of $1 million in NCI spending.
On an accrued basis, capex totaled $130 million net to Murphy, excluding King's Quay.
Prices continued to improve in the fourth quarter with oil realizations at an average of $42, the highest, of course, seen since quarter 1, and natural gas at $2.36 per 1,000 cubic feet, also far ahead of prior quarters.
On Slide 5, our full year 2020 production averaged 164,000 barrels of oil per day.
Overall, for the year, we averaged nearly $38 per barrel for realized oil prices with $1.85 per 1,000 cubic feet for natural gas.
Cash capex for the year totaled $760 million, which included $23 million of NCI capex.
On an accrued basis, capex totaled $712 million, excluding King's Quay and NCI spending as per our guidance.
Our proved reserve base remains sizable at year-end 2020, with 697 millions of oil -- barrels of oil equivalent, comprised of 41% liquids and 51% proved developed.
Approved reserve life is maintained at more than 11 years.
Overall, our total approved reserves were 13% lower from the year-end 2019 due to two primary events.
The change in capital allocation of the current five-year plan reduced PUDs by over 100 million barrels equivalent.
Separately, the sanction of the Tupper Montney development in the fourth quarter resulted in the conversion of probable reserves and contingent resources to proven undeveloped, totaling nearly 100 million barrels equivalent.
On Page 7, while total proved reserves were lower year over year, our North American onshore proved plus probable resource remained near 2.5 billion barrels of oil equivalent.
Overall, Murphy continues to hold more than 3,400 undrilled locations across onshore North America.
Slide 8, Murphy recorded a net loss of $172 million or a $1.11 net loss per diluted share for the fourth quarter of 2020.
After-tax adjustments, including, but not limited to, a noncash mark-to-market loss on crude oil derivative contracts and contingent consideration, totaling $159 million resulted in an adjusted net loss of $14 million or a $0.09 adjusted net loss per diluted share.
Overall, our net cash provided by continuing operations rose to $225 million in the fourth quarter, including a $13 million cash outflow from our working capital increase.
When combined with property additions and dry hole costs of $135 million, including $38 million for King's Quay, we had positive free cash flow of $90 million in the quarter.
For full year 2020, our net cash from continuing operations of $803 million included a $39 million outflow from working capital.
Property additions and dry hole costs of $859 million, including King's Quay spending of $113 million, resulted in a negative free cash flow of $56 million for the year.
If we exclude the King's Quay expenditures for the year, we would have some positive free cash flow of more than $55 million.
We continue to maintain a high level of liquidity with $1.7 billion at year-end, including $311 million of cash and equivalents at December 31st.
With our focus on cost reduction measures throughout 2020, we've achieved significantly lower G&A, with an approximately 40% reduction in full year costs from 2019.
Liquidity remains a key focus for Murphy, and our balance sheet remains strong with $1.4 billion available under our $1.6 billion senior unsecured credit facility as well as $311 million of cash and equivalents as of December 31.
Murphy achieved another year of low metrics, including 46% reduction year over year in total recordable incidents.
A key highlight is our goal of reducing greenhouse gas emissions intensity of about 15% to 20% by 2030 from 2019.
On Slide 15, on the Eagle Ford Shale business, we produced 31,000 barrels equivalents per day in the fourth quarter, now comprised of 71% oil.
For the full year, production averaged 36,000 barrels equivalent per day, with $197 million of capex, which includes near $50 million for field development as well.
We brought online 25 operated and 10 nonoperated wells earlier in that year.
Murphy is seeing an average base decline rate of 24% for all wells drilled prior to '21, which, in our view, is very well positioned.
On Slide 16, on the Kaybob Duvernay project, the company produced 10,000 barrels equivalent oil per day in the fourth quarter, comprised of 75% liquids, and averaged 11,000 barrels equivalent per day for the full year.
Overall, Murphy spent $94 million in capex during the year, including Placid Montney, breaking online 16 operated wells in Kaybob and 10 nonoperated wells in Placid.
Most notable in the second quarter in the Kaybob East 15-19 Pad, which is achieving significant results as our best well in Kaybob Duvernay so far, ranking in the top 2% of all Murphy unconventional wells.
In the Tupper Montney, we produced 234 million per day in the fourth quarter and averaged 238 million cubic feet per day full year 2020.
Approximately, $14 million of capex was spent during the year to drill four wells with completions planned this year and ongoing.
In the Gulf of Mexico, our assets there produced 63,000 barrels equivalent of oil per day in the fourth quarter, comprised of 78% oil.
Production volumes were impacted by nearly 4,000 barrels of oil equivalent per day on unplanned downtime due to two subsea equipment issues, in addition to previously guided hurricane downtime in the fourth quarter.
Our full-year 2020 production averaged 70,000 barrels equivalent per day.
We remain on schedule with King's Quay construction at 90% complete and drilling beginning in the second quarter for Khaleesi, Mormont and Samurai development.
In exploration, we participated in the latest OCS Gulf of Mexico lease sale during the fourth quarter, and we were awarded and fully awarded 8 blocks with 5 prospects at a net cost of approximately $5.3 million.
As a result, our Gulf of Mexico interest today totals 126 blocks, spanning to more than 725,000 acres with 54 exploration blocks and 15 key prospects at this time.
For 2021, Murphy plans to spend $675 million to $725 million and achieve production of 155, 000 to 165, 000 barrels equivalent per day.
For the first quarter, we forecast production of 149, 000 to 157, 000 barrels of oil equivalent per day.
Approximately 47% of our 2021 capex is allocated to offshore Gulf of Mexico, with nearly all dedicated to the major long-term projects that achieve first oil in 2022.
Our North American onshore capital budget is $265 million in 2021 and is also focused on maintaining flat production in the Eagle Ford Shale, with $170 million dedicated to bringing on 19 operated wells and 53 nonoperating wells as well as field development, which is 30% of the total spend.
Approximately $85 million is earmarked for newly sanctioned Tupper Montney development program to bring 14 wells online during the year.
The remaining $10 million of capex supports field development and maintenance in the Kaybob Duvernay and nonoperated Placid.
Of note, our oil-weighted shale assets maintain a long runway of drilling with more than 1,400 locations in the Eagle Ford Shale and more than 600 in the Kaybob Duvernay.
The asset generated free cash flow of approximately $50 million in 2020, which is more than sufficient to cover the cash flow requirements in the next 2 years as the development is initiated.
And overall, the current sanction plan requires an average annual capex of $68 million and will generate cumulative free cash flow of approximately $215 million through 2025.
In the fourth quarter, we farmed into an attractive play opening trend for a 10% nonoperated working interest with Chevron as operator.
The first well plan is a Silverback prospect, and we will provide access to -- and we will also be provided access to about 12 blocks through our participation.
Our Tupper Montney development leads to an approximately 8% CAGR from '21 through '24, while oil growth remains at 3%.
As we began with our announcement in 2020 for a lower capital program, the average annual capex through 2024 is approximately $600 million, with 2022 being the peak year due to finalizing the major Gulf projects along with increased Tupper Montney development.

Summary:
Slide 8, Murphy recorded a net loss of $172 million or a $1.11 net loss per diluted share for the fourth quarter of 2020.
After-tax adjustments, including, but not limited to, a noncash mark-to-market loss on crude oil derivative contracts and contingent consideration, totaling $159 million resulted in an adjusted net loss of $14 million or a $0.09 adjusted net loss per diluted share.
For 2021, Murphy plans to spend $675 million to $725 million and achieve production of 155, 000 to 165, 000 barrels equivalent per day.
For the first quarter, we forecast production of 149, 000 to 157, 000 barrels of oil equivalent per day.