AIM oil explorer Range Resources has made an all-share merger offer for Australian listed peer International Petroleum.The off-market takeover offer values International Petroleum at A$105m, with three Range shares being offered for every two of the target company's.Range, which is dual-listed on AIM and the ASX, has already received commitments to a A$20m institutional fundraising and has agreed to provide a US$15m secured loan to International Petroleum over its Russian assets.As well as Russia, International, which is listed on Australia's secondary National Stock Exchange, holds highly prospective assets in Kazakhstan and Niger with total proven, probable and possible reserves of 233m barrels of oil and best estimate prospective resources of 761m barrels of oil and 157bn cubic feet of gas.If it goes ahead, the merger would create an entity with estimated 23.6m proven, 100m probable and 264m barrels possible reserves of oil respectively across six countries, best estimate prospective resources of 802m barrels of oil and 156bn cubic feet of gas, and combined current production of around 1,000 barrels of oil per day equivalent.OH