Category: Oil and Gas business

Underground salt formations offer an option for natural gas storage. These formations are well suited to natural gas storage in that salt caverns, once formed, allow little injected natural gas to escape from the formation unless specifically extracted. The walls of a salt cavern also have the structural strength of steel, which makes it very resilient against reservoir degradation over the life of the storage facility. Salt caverns are formed out of existing salt deposits. These underground salt deposits may exist in two possible forms: salt domes, and salt beds. Salt domes are thick formations created from natural salt deposits that, over time, leach up through overlying sedimentary layers to form large dome-type structures. Typically, salt domes used for natural gas storage are between 6,000 and 1,500 feet beneath the surface. Salt beds are shallower, thinner formations. Because salt beds are wide, thin formations, once a salt cavern is introduced, they are more prone to deterioration, and may also be more expensive to develop than salt domes. Once a suitable salt dome or salt bed deposit is discovered, and deemed suitable for natural gas storage, it is necessary to develop a ‘salt cavern’ within the formation. Essentially, this consists of using water to dissolve and extract a certain amount of salt from the deposit, leaving a large empty space in the formation. This is done by drilling a well down into the formation, and cycling large amounts of water through the completed well. This water will dissolve some of the salt in the deposit, and be cycled back up the well, leaving a large empty space that the salt used to occupy. This process is known as ‘salt cavern leaching’. Cushion gas requirements are the lowest of all three storage types, with salt caverns only requiring about 33 percent of total gas capacity to be used as cushion gas. Salt caverns are best suited for peak load storage. Salt caverns are typically much smaller than depleted gas reservoirs and aquifers and usually take up only one one-hundredth of the acreage taken up by a depleted gas reservoir. As such, salt caverns cannot hold the volume of gas necessary to meet base load storage requirements. However, deliverability from salt caverns is typically much higher than for either aquifers or depleted reservoirs. Therefore natural gas stored in a salt cavern may be more readily (and quickly) withdrawn, and caverns may be replenished with natural gas more quickly than in either of the other types of storage facilities. Moreover, salt caverns can readily begin flowing gas on as little as one hour’s notice, which is useful in emergency situations or during unexpected short term demand surges. Salt caverns may also be replenished more quickly than other types of underground storage facilities

Intertidal wetlands that occur on the margins of estuaries, protected bays, and the landward side of barrier islands

Secondary recovery uses other mechanisms than purely the natural pressure – such as gas reinjection and water flooding – to produce residual oil and gas remaining after the primary recovery phase

The relative amount of water, oil and gas in the pores of a rock

The Sakhalin-1 Project is an oil and gas development on the northeast shelf of Sakhalin Island. It was declared commercial in October 2001. The Project area is comprised of the Chayvo, Odoptu and Arkutun-Dagi fields. Total recoverable reserves are estimated to be 2.3 billion barrels of oil and 17.1 trillion cubic feet of natural gas. Exxon Neftegas Limited, an affiliate of Exxon Mobil Corporation, is the operator. The Sakhalin-1 Project is one of the most ambitious, world-scale projects developed by international oil and gas industry to date, and represents one of the largest single foreign direct investments in Russia. Project benefits to Russia include direct revenues to the Russian state estimated at over US$ 50 billion over the life of the Project.

Type of survey to help define a salt sediment near a wellbore. This technique takes advantage of the fact that sound travels faster through the salt than the surrounding soft sediments and enables to receive a profile of the salt relative to the borehole

Such as when a shipment of LNG is diverted from a potentially higher paying market (e.g. Japan) to a lower paying market (e.g. US) because Japan is not able to take the LNG whereas the US is able due to large storage capacity

Secondary target refers to other possible reservoirs that may be above or below the primary target, which are usually thought to be not as attractive for various reasons as the primary target, possibly because they are thinner, of variable quality, are of low poroperm qualities, etc. Primary target usually refers to the most important reservoir which an O&G company hopes will contain hydrocarbons when drilling. In real life secondary targets can turn out to be better than primary, or both targets can be good or both bad