Chinese name: Natural gas exploitation is due to: low natural gas density: 0.75 ~ 0.8kg/m3 buried in underground closed geological structure: Overview, China development, relevant policies, investigation methods, overview: low natural gas density: 0.75 ~ 0.8kg/m3, low gas column pressure at the bottom of the well; Natural gas has low viscosity and low flow resistance in strata and pipelines; Because of its large expansion coefficient, its elastic properties are also large. Therefore, natural gas exploitation generally adopts self-injection method. This is basically the same as flowing oil production. However, because the gas well pressure is generally high and the natural gas is flammable and explosive, the pressure bearing capacity and sealing performance of the gas production wellhead device are much higher than that of the oil production wellhead device. Natural gas exploitation also has its own characteristics. First of all, natural gas, like crude oil, is often a storage system with bottom water or edge water. With the development of natural gas, the elastic energy of water will drive water into gas reservoirs along the high permeability zone. In this case, due to the hydrophilicity and capillary pressure of the rock itself, the invasion of water is not the effective displacement of gas, but the sealing of undrained gas in cracks or holes, forming a dead zone. This part of the high-pressure gas trapped in the water invasion zone can be as high as 30% ~ 50% of the pore volume of the rock, thus greatly reducing the ultimate recovery of the gas reservoir. Secondly, after the water comes out of the gas well, the seepage resistance of gas flowing into the bottom hole will increase, and the total energy consumption of gas-liquid two-phase pipe flow along the oil well will increase significantly. With the increasing influence of water invasion, the gas production of gas reservoir decreases, the flow capacity of gas well weakens, and the output of single well drops rapidly until the bottom hole is seriously flooded and production is stopped. At present, the control of gas reservoir flooding mainly starts from two aspects, one is drainage, and the other is water plugging. Water plugging is to separate the gas-producing layer from the water-producing layer by mechanical plugging and chemical plugging, or to establish a water blocking barrier in the reservoir. At present, there are many drainage methods, the main principle of which is to remove the water in the wellbore. The technical term is drainage gas recovery method. Since the development of 1998 China, the discovery of super-large gas fields in Tarim Basin, Ordos Basin and Sichuan Basin has not only unexpectedly opened China's national natural gas era, but also greatly increased the country's chips in the international natural gas market. The proven geological reserves of China onshore gas field exceed 90% of the total reserves of Luhai gas field. The judgment of onshore gas field productivity will make natural gas operators have an important impact on the decision-making of importing natural gas and domestic market. On the other hand, since 10, the optimism about the offshore natural gas production prospect in China has been high. However, if we take off the glasses of nationalists, China's natural gas industry will find that there is a considerable gap between the expected and actual development and application: there are regional disputes over gas fields in the East China Sea and the South China Sea, and it is difficult to make a big change in the status quo during the Twelfth Five-Year Plan, the Thirteenth Five-Year Plan or even the Fourteenth Five-Year Plan; Except for the newly developed Liwan 3- 1 gas field in the Pearl River Mouth Basin, other offshore gas fields under development and utilization are small and medium-sized gas fields, and the total production capacity is only close to the maximum gas supply capacity of 1.5 coastal receiving stations. Natural Gas Exploitation and Gathering in Tarim Basin In recent years, China's oil and gas exploitation industry has developed rapidly. From June 5438 to February 65438, 2006, the total industrial output value of China's oil and gas exploration industry reached 7590733565438+ million yuan, an increase of 24.74% over the same period in 2005. Accumulated product sales income was 773,655,604,000 yuan, an increase of 27.24% over the same period of 2005; The accumulated profit was 363,568.825 million yuan, an increase of 24.22% over the same period in 2005. During the period of 1- 1 1 in 2007, the total industrial output value of China oil and gas exploitation industry was 726174178,000 yuan, an increase of 4.82% over the same period in 2006. Accumulated product sales revenue was 767,905,565,438+05,000 yuan, an increase of 6.98% over the same period of 2006, and accumulated total profit was 334,865,438+07,296,000 yuan, a decrease of 7.72% over the same period of 2006. From June 5,438+0 to June 5,438+0, 2008, the total industrial output value of China oil and gas exploration industry was155,299,892,000 yuan, an increase of 46.85% over the same period in 2007. Accumulated product sales revenue of 154, 189, 13 1 000 yuan, an increase of 42.07% over the same period in 2007; The accumulated profit was 78,834,704,000 yuan, an increase of 665,438+0.23% over the same period in 2007. Development and Aggregation of Oil and Gas Fields in Xiao Chun and Pinghu A series of sedimentary basins have been developed off the coast of China, covering a total area of nearly one million square kilometers, with rich oil and gas prospects. From north to south, these sedimentary basins include Bohai Basin, North Yellow Sea Basin, South Yellow Sea Basin, East China Sea Basin, Okinawa Trough Basin, Taixi Basin, Southwest Taiwan Province Basin, Taidong Basin, Pearl River Mouth Basin, Beibu Gulf Basin, Yinggehai-Qiongdongnan Basin and South China Sea Basin. Offshore oil and gas exploration in China is mainly concentrated in the Bohai Sea, the Yellow Sea, the East China Sea and the northern continental shelf of the South China Sea. According to the Outline of National Marine Economic Development Plan issued by the State Council on May 9, 2003, China's offshore oil resources are about 24 billion tons, and the theoretical reserves of marine renewable energy are 630 million kilowatts. By 20 10, the added value of marine industry will account for more than 5% of GDP, and marine economy will become a new growth point of national economy. During the period of 2005-2020, the output of oil and natural gas in China is far from meeting the demand, and the gap between supply and demand will become larger and larger. The demand for natural gas in China will increase at a rate of about 15% every year, and will exceed 10 billion cubic meters in 20 10, and will reach 200 billion cubic meters in 2020, accounting for 10% of the total energy composition. According to analysis, it is estimated that by 2020, offshore oil will account for 35% of global oil production. At present, the proportion of offshore oil in the total oil exploitation in China is less than 1/5, and there is still great potential for improvement. Relevant policies Chapter I General Provisions Article 1 These Standards are formulated in accordance with the Accounting Standards for Enterprises-Basic Standards for the purpose of regulating the accounting treatment of oil and gas (hereinafter referred to as oil and gas) exploitation activities and the disclosure of relevant information. Article 2 Oil and gas exploitation activities include the acquisition of rights and interests in mining areas and the exploration, development and production of oil and gas. Article 3 Other relevant accounting standards shall apply to the accounting treatment of oil and gas storage, gathering and transportation, processing and sales other than oil and gas exploitation activities. Chapter ii accounting treatment of rights and interests in mining areas article 4 rights and interests in mining areas refer to the rights obtained by enterprises in exploration, development and production of oil and gas in mining areas. Mining rights and interests are divided into proven mining rights and interests and unexplored mining rights and interests. Proved mining area refers to the mining area with proven economic recoverable reserves. Unexplored mining area refers to the mining area where proven economic recoverable reserves have not been found. Proved economic recoverable reserves refer to the amount of oil and gas that can be reasonably determined from known oil and gas reservoirs under the existing technical and economic conditions according to geological and engineering analysis. Article 5 The costs incurred in obtaining mining rights shall be capitalized when incurred. The mining rights and interests obtained by an enterprise shall be initially measured according to the cost at the time of acquisition: (1) The cost of applying for obtaining the mining rights and interests includes the exploration right use fee, mining right use fee, land or sea area use fee, agency fee and other expenses directly attributable to the mining rights and interests. (2) The cost of purchasing the rights and interests of the mining area includes the purchase price, agency fees and other expenses directly attributable to the rights and interests of the mining area. The maintenance expenses of mining rights and interests, such as mining royalties and rents, are included in the current profits and losses. Article 6 Enterprises shall make losses on the rights and interests of proven mining areas by using the yield method or the life average method. If the production method is used to draw the loss, the loss can be calculated according to a single mining area. It can also be calculated according to the mining group composed of several adjacent mining areas with the same or similar geological structure characteristics or reservoir conditions. The calculation formula is as follows: loss of rights and interests in proven mining area = book value of rights and interests in proven mining area t loss rate of rights and interests in proven mining area = current output of proven mining area/(proven economic recoverable reserves at the end of proven mining area+current output of proven mining area) Article 7 The impairment loss of rights and interests in mining area shall be confirmed according to different situations: (1) Impairment of rights and interests in proven mining area shall be handled in accordance with the Accounting Standards for Enterprises No.8-Asset Impairment. (2) The rights and interests of unproven mining areas shall be tested for impairment at least once a year. If the acquisition cost of a single mining area is high, the impairment test should be carried out on the basis of a single mining area. And determine the amount of impairment of rights and interests in unexplored mining areas. If the purchase cost of a single mining area is low and it has the same or similar geological structure characteristics or reservoir conditions with other adjacent mining areas, the impairment test can be carried out according to the mining group composed of multiple adjacent mining areas with the same or similar geological structure characteristics or reservoir conditions. The difference between the fair value and book value of the rights and interests in the unexplored mining area is recognized as impairment loss and included in the current profit and loss. Once the impairment loss of the rights and interests in the unexplored mining area is confirmed, Article 8 If an enterprise transfers the rights and interests in the mining area, it shall be handled in accordance with the following provisions: (1) If all the proven rights and interests in the mining area are transferred, the difference between the transfer income and the book value of the rights and interests in the mining area shall be included in the current profits and losses. If the proven rights and interests in the mining area are transferred, the book value of the transferred rights and interests in the mining area shall be calculated and determined according to the fair value ratio of the transferred rights and interests to the retained rights and interests. The difference between the transfer income and the book value of the transferred mining right is included in the current profit and loss. (2) If all the unproven mining rights and interests for which impairment provision has been made are transferred, the difference between the transfer income and the book value of the unproven mining rights and interests shall be included in the current profit and loss. If the transfer income is greater than the book value of the mining right, the difference is included in the current profit and loss. If the transfer income is less than the book value of the rights and interests in the mining area, the book value of the rights and interests in the mining area shall be offset by the transfer income, and no profit or loss shall be recognized. If the transfer income is less than the original book value of the rights and interests in the mining area, the transfer income will offset the original book value of the rights and interests in the mining area, and no profit or loss will be recognized. When the remaining rights and interests of the last unexplored mining area of the mining group are transferred, the difference between the transfer income and the book value of the rights and interests of the unexplored mining area is included in the current profit and loss. Ninth unproven mining areas (groups) found proven economic recoverable reserves, unproven mining areas (groups) into proven mining areas (groups). It should be converted into the rights and interests of the proven mining area according to its book value. Article 10 If an unproven mining area is abandoned because proven economically recoverable reserves have not been found, it shall be resold according to the book value at the time of abandonment and included in the current profits and losses. The abandonment cost caused by factors such as unfinished voluntary workload is included in the current profit and loss. Chapter III Accounting Treatment of Oil and Gas Exploration Article 11 Oil and gas exploration refers to geological survey, geophysical exploration, drilling activities and other related activities for the purpose of identifying exploration areas or oil and gas reserves. Article 12 Oil and gas exploration expenditures include drilling exploration expenditures and non-drilling exploration expenditures. Expenditures on drilling and exploration mainly include expenditures on activities such as drilling exploratory wells, exploratory detailed wells, evaluation wells and data wells; Expenditures for non-drilling exploration mainly include expenditures for geological survey, geophysical exploration and other activities. Thirteenth after the completion of the well, it is determined that the proven economic recoverable reserves of the well should be transferred to the cost of the well and related facilities. If it is determined that no proven economic recoverable reserves have been found in this well, the drilling expenditure will be included in the current profit and loss after deducting the net salvage value. If it is determined that proven economically recoverable reserves have been found in some intervals, the drilling and exploration expenditures in effective intervals where proven economically recoverable reserves have been found should be transferred to the cost of wells and related facilities, and the accumulated drilling and exploration expenditures in ineffective intervals should be transferred to current profits and losses. If the exploratory well does not determine whether proven economic recoverable reserves are found, the drilling expenditure will be temporarily capitalized within one year after completion. Article 14 If it is still uncertain whether proven economically recoverable reserves are found after one year of exploration well completion, and the following conditions are met, the capitalized drilling expenditure of the well should continue to be capitalized temporarily, otherwise it will be included in the current profit and loss: (1) The well has found enough reserves, but further exploration activities are needed to determine whether it belongs to proven economically recoverable reserves; (2) Further exploration activities have been carried out or there are clear plans, and will be carried out soon. If economically recoverable reserves are found in the exploration wells that have spent drilling and exploration expenses, the spent drilling and exploration expenses will not be adjusted, and the expenses incurred in re-drilling and completion will be capitalized. Fifteenth non drilling and exploration expenditures shall be included in the current profits and losses when incurred. Chapter iv accounting treatment of oil and gas development article 16 oil and gas development refers to the activities of building or upgrading wells and related facilities in proven mining areas for oil and gas acquisition. Article 17 Expenditure incurred in oil and gas development activities shall be capitalized as the cost of wells and related facilities formed by oil and gas development. The expenses of wells and related facilities formed by oil and gas development mainly include: (2) the expenses of purchasing and building wells, including casing, tubing, pumping equipment and wellhead devices. Well construction includes drilling and completion; (3) the cost of purchasing and building enhanced oil recovery system; (4) Expenditure on the purchase and construction of gathering and transportation facilities, separation and processing facilities, metering equipment, storage facilities, various offshore platforms, submarine and onshore cables, etc. Eighteenth expenses incurred in drilling to the proven horizon in the proven mining area shall be regarded as oil and gas development expenses; According to Articles 13 and 14 of this Code, the expenses for drilling undiscovered horizons in order to obtain new proven economic recoverable reserves shall be regarded as drilling expenses. Chapter V Accounting Treatment of Oil and Gas Production Article 19 Oil and gas production refers to the activities of exploiting oil and gas in oil and gas reservoirs to the surface and collecting, transporting, processing, on-site storage and mining area management in mining areas. Twentieth oil and gas production costs include the loss of rights and interests in related mining areas, the loss of wells and related facilities, the depreciation of auxiliary equipment and facilities, operating expenses, etc. Operating expenses include direct and indirect expenses incurred in the process of oil and gas production and mining management. Article 21 An enterprise shall make provision for impairment of oil wells and related facilities by production method or life average method. Wells and related facilities include exploratory wells with proven economic recoverable reserves, wells formed in mining activities and various facilities directly related to mining activities. If the production method is used to calculate the dilution, the loss can be calculated by a single mining area, or by a mining group composed of several adjacent mining areas with the same or similar geological structure characteristics or reservoir conditions. The calculation formula is as follows: depletion of mining wells and related facilities = book value of mining wells and related facilities at the end of t = current output of mining area/(proven development economic recoverable reserves at the end of mining area+current output of mining area) proven development economic recoverable reserves, including the proven economic recoverable reserves that have been fully put into mining after the completion of well pattern drilling and supporting facilities construction in mining area, and the corresponding increased recoverable reserves after the facilities required for enhanced oil recovery technology are completed and put into production. Article 22 Auxiliary equipment and facilities such as seismic equipment, construction equipment, vehicles, maintenance workshops, warehouses, supply stations, communication equipment and office facilities shall be handled in accordance with the Accounting Standards for Enterprises No.4-Fixed Assets. Article 23 If the obligations undertaken by an enterprise for the disposal of abandoned mines meet the conditions for the recognition of estimated liabilities in the Accounting Standards for Enterprises No.65438 +03- Contingencies, it shall be recognized as estimated liabilities, and the book value of wells and related facilities shall be increased accordingly. If the estimated liabilities are not met, they shall be dismantled, moved and located when abandoned. Should be included in the current profit and loss. Abandonment of the mining area means that the last well in the mining area has stopped production. Article 24 The impairment of wells and related facilities, auxiliary equipment and facilities shall be handled in accordance with the Accounting Standards for Enterprises No.8-Impairment of Assets. Chapter VI Disclosure Article 25 An enterprise shall disclose the following information related to oil and gas exploitation activities in its notes: (1) domestic and foreign oil and gas reserves data at the beginning and end of the year; (2) Total expenditures incurred in the acquisition of mining rights and interests, oil and gas exploration and oil and gas development at home and abroad in the current period; And (3) the original book value of mining rights and interests, wells and related facilities. The original book price, accumulated amount of depreciation and impairment reserve of auxiliary equipment and facilities related to oil and gas exploration activities and their accrual methods. Survey method 1, seismograph observation, measuring the shock wave produced by explosive charge, thus knowing the structure of rocks under the surface. 2. Geological exploration to find the location of special rock formations (oil or natural gas). 3. Check the gravity of the earth to measure the change of gravity and detect the existence of oil or natural gas.