Shares in oil and gas company Petroceltic (LSE: PCI) have traded as much as 9% higher today after it released two pieces of encouraging news flow. The first concerns its financial standing, with Petroceltic stating that its lenders have agreed to a further waiver of repayments under its senior bank facility to 4 March 2016.

Furthermore, Petroceltic has stated that its lenders have indicated their willingness to consider such further waivers as may be required to continue the strategic review process based on circumstances applying at the time of any application. This shows that the company’s near-term outlook may be more positive than had been priced-in by the market, and that Petroceltic may be afforded the breathing space it needs to turn around its financial performance.

The second piece of news flow concerns Petroceltic’s operations in Algeria. It has commenced development drilling on the Ain Tsila gas and condensate field, after the AT-10 well was spudded. And with it being a relatively high-quality asset, Ain Tsila has the potential to deliver positive news flow moving forward.

However, with the company’s finances still being in a precarious position and there being good value stocks elsewhere within the oil & gas sector, it may be prudent to watch rather than buy Petroceltic at the present time.

Value for money?

Also reporting today was Petra Diamonds (LSE: PDL). While it’s on target to meet production guidance for the full year, lower diamond prices continue to weigh on its financial performance. As such, revenue for the first half of the year declined to $154m, which represents a fall of 28% versus the first half of the previous year.

While disappointing, Petra Diamonds has experienced firmer pricing since the end of the first half of the year and with its production being on track, as well as an expected weighting of sales towards the second half of the year, it remains upbeat on its prospects. In addition, with the company’s shares trading on a price-to-earnings (P/E) ratio of 14.1, they appear to offer fair value for money at the present time.

Clearly, there’s scope for further downward pressure on the company’s performance from a declining diamond price, but for long-term investors, Petra Diamonds could be worth a closer look.

Index beater

Meanwhile, Petrofac (LSE: PFC) is due to report results this week. Its shares have held up reasonably well in the last year despite the disappointing performance for the oil & gas sector. In fact, Petrofac has beaten the FTSE 100 in the last 12 months, with its shares being down by 10% versus 12% for the wider index.

Looking ahead, Petrofac is expected to yield 5.4% in the current financial year and with its shares trading on a forward P/E ratio of 7.9, it appears to offer excellent value for money. Certainly, it’s facing challenging trading conditions, but it seems to be successfully adapting its strategy and business model so as to deliver rising profitability over the medium-to-long term. Therefore, for investors who can live with above average volatility, as evidenced by a beta of 1.5, Petrofac could be a worthy buy.

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Peter Stephens owns shares of Petrofac. The Motley Fool UK owns shares of and has recommended Petrofac. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors.