Cash flow from the project, which is 100% owned by Mosman, was also positive over the period.
At Welch, work in recent months has focused on workovers and production optimisation.
November oil sales amounted to 689 barrels (in October the figure was 843).
Shares jumped 53% to 1.38p as the first phase of workovers has established production of up to 40 barrels per day.
An investment decision on a horizontal drilling programme will be taken later this year after a reserves report by Moyes & Co, the statement added.
Arkoma report awaited
In Oklahoma, initial oil and gas production rates from the Union Valley zone of the Arkoma Stacked Pay project (10%), indicated that it alone may be sufficient for economic field development at Arkoma.
The operator, though, proposes to produce the Wilcox together with the Viola, Woodford and Union Valley oil and gas production zones.
Mosman has an option to take its stake up to 55% and will make an investment if it is satisfied with a study also commissioned from Moyes & Co.
The company sees potential for Arkoma to add both production and oil reserves, but, it will only exercise its option if it can be fully satisfied by the assessment results.
Other opportunities identified
At Strawn, in Texas, initial flow rates were not maintained and no further workovers are planned in the short term.
Two other potentially attractive acquisition opportunities have been identified said John W Barr, Mosman’s chairman.
“Encouragingly, 2018 has started positively with increasing cash flow," he added.
Mosman takes control of GEM board
Elsewhere, Mosman has replaced all of the directors of GEM International Resources (CVE:GI) with its own nominees including John Barr.
Mosman owns 7.6mln shares in GEM, which is currently suspended on the Canadian Venture Exchange after failing to lodge its financial report.