Current State and Development Trends of Deep Sea Oil and Gas Exploration

TECHNOLOGY and EQUIPMENTCurrent State and DevelopmentTrends of Deep Sea Oil and GasExplorationang wen(SINOPEC Research Inoleum EngineeringAs people probe deeply into submarine exploration will lie in deep water in the future, but only 3% have beenand development of oil, gas hydrates and other mineral produced so far, so it still has a great potential. Newlyreserves,deepwater oil and gas development has become proven oil and gas reserves were 16.4 billion tons of oila hotspot for world petroleum industry and the frontier of and gas equivalent from 2000 to 2005, 41% were in deeptechnological innovation. In the past few years, petroleum sea, 31% in shallow sea, and 28% on land. On the basiscompanies engaged in deep sea exploration put more effort of Offshore Resources, there were 434 marine oil and gason exploration and development of marine resources. development projects worldwide from 2001 to 2007, 48%However, the companies capable of carrying out deep of which were conducted in deepwater with water thesea operation can be reckoned up on the fingers of one depth more than 500m and 22% were in ultra deepwatershand, because such operation involves technological with the water depth more than 1, 200m.support, logistics support, legal issues, warning and Now more than 100 countries have been engaged inavoidance of natural disasters. Technologically, to have a offshore petroleum exploration, and more than 50 havebetter understanding of the technical difficulties in deep carried out deep sea exploration. The U.S. has the largestsea exploration and increase science and technology amount of offshore drilling in the world, and it has moreinvestment could not only ease power shortages in China, than 19,000 wells in the Gulf of Mexico and about 100but enable proven technologies to be integrated and then wells under production in Gulf Area. Besides, UKdevelop high-efficiency technological systemsMalaysia, India, Russia and some other countries havealso been engaged in a great quantity of marine drillingOverview of deepwater and ultra deepwater BP, Petrobras, Statoil, Exxon Mobil, Shell, Unocal,explorationand some other companies equipped with deepwaterBased on international conventions, water domains less exploration and development technologies usuallythan 400m deep, 400-1, 500m deep and more than 1, 500m cooperate with each other to carry out exploration anddeep are named as conventional water depth, deepwater exploitation of中国煤化工 North Seaand ultra deepwater, respectively. As predicted by the the Gulf of Muth China SeaWorld Deepwater Report, 44% of oil and gas reserves became targetsC N MH Go deep sea oil24 CHINA OIL& GASo.3.2011TECHNOLOGY and EQUIPMENTand water activities from 2005 to 2008. Global deepwater few European developed countries have mastered coreoil and gas exploration is witnessing a rapid development, deepwater exploration technologiesas the continental-shelf oil and gas exploration extends tothe oceanTechnological difficulties in deepwater and ultradeepwater drillingCurrent state of deepwater and ultra deepwater (1)Deepwater exploration and development vsoil and gas explorationtraditional drillingCurrent state of deepwater and ultra deepwater Deepwater drilling has to deal with the problems asdrilling technologyfollows: the berth of offshore fixed platforms or freeExploration and development of deepwater oil and gas floating platforms in deep sea, the unstabilizing geofactorresources features in high and new technologies, high of deepwater sea bed, the deepwater well control whilerisk, high investment and high yield, yet the high yield floating, and effective protection of deep sea environment,and huge additional benefits from deepwater oil and gas etc. With respect to traditional onshore drillingexploration and development lure the attention of world's technology, marine drilling technology has the followinglarge petroleum companies. Deepwater drilling data in characteristicsthe past few years show that global drilling capacity has Firstly, how to locate the exact position of oil and gasreached 10,000m, and there have been 15 drilling vessels reservoirs during oil and gas exploration. Reservoir fluidsoperating in deepwaters with the water depth more than get complicated as water depth rises. Some technologies3, 000m, with the maximum lifting capacity being 14,000 for oil and gas exploration in deepwaters have to betons during offshore operation, deepwater pipe-laying employed for offshore drilling engineering, includinglength has reached 12,000km, remedial operation could the long-cable seismic signal measuring and analytibe carried out in the area with the water depth more than technology, the multi-wave field analytic technology, the2,000m, and there have been more than 204 production technology for identification of large reservoirs in deeprigs operating in deepwaters. There were 2, 100 subsea waters, and the technology for identification of subtle oiproduction systems in 2003 and 5, 700 in 2007. The and gas reservoirs, etc. The expenditure for marine oildepth of drilling with semi-submersible platforms in and gas exploration is five to six times land exploration,the world was mostly between 60 and 2,000m, with a drilling cost is higher than 10,000 RMB per meter, 300 tomaximum of 3, 100m. The U.S. is worlds first country 600 million dollars have to be used for construction of aengaged in deep sea research and development, and it medium-sized offshore oilfield, and two to three billionowns advanced platforms and submarine completion dollars are needed to construct a large one. Thereforeequipment. As well some European countries have their various technologies have to be used to thoroughlyown merits in deep sea exploration and development. analyze regional tectonics and hydrocarbon accumulationFig. I presents the statistics of success ratio of deepwater laws, accurately locate hydrocarbon structures of hugeexploration in various places of the world. The success reserves and high flow potential, and integrate differentratio of deepwater exploration is extremely confined measuring and analytic technologies with approaches forbecause of its complexity and high risk. Only the U.S. and target identificationSecondly, high and new technologies for drilling indeepwaters. Difficulties in deepwater drilling mainlyinclude the unstabilizing geofactors in deepwater seabed, geologic hazards in shallow layers, influence of lowtemperature in sea floor, well control in deep waters, andeffective environmental protection of deep waters. Drillingtools and technologies available for shallow watersare not fit for deep waters. Remote Operated Vehicles(ROV and deep sea coring rigs have to be equipped forsubmarine prospecting and survey, sometimes mannedsubmersibles and中国煤化工 ve to beverage employed, meanwhileepwaterFig, I Sucess ratio of oil and gas exploration in deepuaters of the world. oil and gas drillingCNMHGatoningCHINA OIL& GAS 25No3.2011TECHNOLOGY and EQUIPMENTtechnology, the technology of large marine jackup experienced classification society. For instance, the Sthvessel, the gordian technologies of 3,000m-deep semi- generation BINGO-9000 Semi-submersible Platformsubmersible platform and deepwater free floating drilling COSCO Dalian Shipyard constructed for OCEAN RIGvessels, the technology of drilling fluid and completion is to select three representative fatigue hot points forfluid, and the technology for subsea operation, etc )and analysis and checking from the floating structure. In facttechnologies for deepwater oil and gas development semi-submersible platforms are always driven by wind(including the deep sea oil recovery technology, the wave, so to calculate the load on platforms is extremelydeepwater platform technology, the technology for overall complicated and dynamic. Structural strength anddevelopment of deep sea oil and gas fields, the technology antifatigue is a cutting-edge problem for contemporaryof submarine pipeline, the technology for cable design, drilling platform manufacturing industry. As high-strengthand the technology for subsea operation, etc.)steel is widely used in hull structure, the problem ofThirdly, higher requirements on marine drilling fatigue failure gets more prominentapparatus and logistics. As water depth increases, (3)Special requirements on development of gasreservoir fluids get more complicated. In addition, weather hydrate technologyextremes may be encountered in high sea, so it is required Based on current resource information. methane inthat more advanced drilling and completion technologies, subsea gas hydrates is about 1.8x10 worldwidefloating production systems, deepwater platforms of about 1. 1x10 tons, which is adequate for human beingsgood performance and high erosion resistance, and more to use 1,000 years in accordance with the current energyintelligent submarine product systems be employed for consumption rate. Because gas hydrate could not existdrilling in deepwatersin solid state under normal temperature and pressure,(2) Peculiar natural environment mainly threats the there are essential differences between the technology forsafety of drilling vesselsdrilling and development of gas hydrate and the traditionalFirst, fatigue failure of hull structure and equipment. one. At present, there are the following technologiesHow to maintain stability and safety of drilling vessels for gas hydrate exploration: the seismic reflection andwhen encountered with weather extremes is the biggest logging technology of high resolution and multiple tracks.challenge to deepwater and ultra deepwater drilling, the technology of geologic survey or subsea imaging, thewhich involves some frontier science and unknown high- geochemical anomaly detecting and drilling technologytech sectors such as marine environment, fluid dynamics, Coring is the most direct problem in drilling gas hydrate,steel structure, and boats and ships manufacturing, etc. i.e. how to acquire complete gas hydrates while keepingContemporary marine steel structure such as mobile the temperature and pressure. Moreover, gas hydratedrilling platform, especially fixed pile drilling platform recovery is a bigger challenge to traditional drillingis inevitably affected by some natural factors: the long- technology. Now there are three types of technologiesterm affect and shore vibration from wind wave and ocean being studied: the technology of thermal excitation, thecurrent in marine environment; the long-term impact on technology of chemical reagent, and the technology ofplatforms by ice load and floating ice with tide in harsh pressure reduction. However, all the technologies couldwaters,corrosion by low temperature and sea water. All not be used commercially even though they are mature,the factors above exert adverse effects on steel-structure if the effect of bulk exploitation on the environmentplatforms, and the most prominent problem is the brittle The U.S. scientists propose to inject CO, into subsea gasfracture and fatigue failure of steel structure in the sea. hydrate reservoirs, because CO2 is easier to form gasAmong them, the problem of fatigue failure has not been hydrate as compared with methane. Therefore, CH, couldeffectively solved, and it directly threats the safe use of be acquired safely, meanwhile, CO, generating from thesteel structure in the seaburning of gas hydrate could not increase greenhouseSecond, hull endurance check still exists some defects. gases. All the technologies mentioned are brand newIn order to evaluate the fatigue resistance of the technology R&D and integration, going beyond traditionalentire floating structure, a large number of connectors drilling technology and contemporary completionof different component parts have to be selected for technologyfatigue check, and great computational effort has to be (4)Safety problem caused by poor management andmade for checking a point. Generally the checking points logistics中国煤化工are determined by engineering practice or discussion of It is veryCNMH GIng platforms26 CHINA OIL&GASTECHNOLOGY and EQUIPMENThigh-efficiency technological management and safe as temperature fluctuation, marine animals'adhesion andlogistics support. Management of offshore drilling nibbling)platforms is directly related to the safety of drilling vessels (4) Well track design will fulfill real-time andand all personnels life. So a powerful and high-efficiency intelligentizationlogistics support system could keep the loss resulted from So-called intelligentization indicates that well trackaccidents to a minimum. or remove hidden hazardscan be adjusted by use of all stratigraphic informationacquired from drilling, based on the principle ofDevelopment trends of deepwater and ultra maintaining hole stability to the utmost and obtaining thedeepwater technologyoptimum drilling rate. Real-time is to adjust well trackWith regard to the complexity and uncertainty of during drilling without delay by use of geosteering toolsdeepwater environment, contemporary ocean drilling on the basis of accurate processing of logging informationplatforms have the following characteristics: intensive during operation, so as to avoid the volatile zone and thetechnology; intensive capitals; high risk, and a long time extension to target layersfrom discovery to formal operation. Deepwater and ultra (5) New drilling technologies will be developeddeepwater drilling appears to have such trends as followsLaser drilling technology may be used in ocean(1)Future deep sea exploration vessels will be exploration for its advantages of small equipment, highdominated by semi-submersible platformsefficiency, and low cost for wide applicationSemi-submersible platforms show better horizontal (6) Subsea maintenance and installation technologyeffects in waves and are favorable for drilling, moreover, extends to ultra deepwatersproduction platforms, pipe-laying vessels, supply vessels, Contemporary ocean drilling technology could assureand offshore floating cranes are all submersible. As ocean normal maintenance and replacement of subsea equipmentdevelopment extends to deepwaters, such platforms will in 2,000m-deep waters. However, few maintenancebe more widely used. The BINGO-9000 semi-submersible equipment and technologies could be used in 3, 000m-deepdrilling platform is a common onewaters, which may involve the use of manned submarine(2) Automatization of drilling equipment will be more technology, deep sea robots, and subsea accurateimprovedmeasuring and location technology. Such technology hasThis is mainly represented by the high-precision to been employed for all types of subsea operation aspositioning technology(such as satellite positioning, water depth risesradio-positioning, and acoustic positioning, etc. ) thesatellite data communication technology, and the highprecision dynamic positioning technology. Moreover, thecomprehensive application of such technologies will boostthe intelligentization of ocean drilling equipments. Toenhance the capability of resisting weather extremes andcarrying out comprehensive surveys, larger ocean drillingplatforms are bound to be used in the future(3) Supporting drilling technologies and equipmentswill be further improvedHigh strength and light new materials will be widelyused. Supporting technologies mainly include thedirectional drilling technology (especially the horizontalwell technology and the extended-reach technology ),and the technology for drilling in polar ocean. Relevantsubsea production apparatus mainly includes riser, subseablowout provender, and subsea X-tree, of which thetarget is to adapt to the complicated seabed environmentand resist higher seawater pressure in the seabed withlow pressure and high corrosion, and present higherability to resist subsea environmental destruction(suchYH中国煤化工CNMHGCHINA OIL& GAS 27No.3,2011TECHNOLOGY and EQUIPMENTCurrent state of china's marine drillingproduction in deepwaters and ultra deepwaters.MoreChina's marine drilling lags behind the international ideas feasible for designing offshore drilling platforms(1) Deep sea drilling technology could not satisfy and constructing the 6th generation driling vese esigninglevel as follows:should be proposed, based on the experience inthe requirements, in particular, the application of large2) To carry out research and development of coreequipment and supporting technology for production technologies with our own independent intellectualprocess are urgently needed to be adjustedproperty rights, on the basis of absorbing foreign(2)China's shipbuilding industry has reached advanced technologiesinternational advanced level, but the technology for (3)China has abundant marine oil and gas resources,designing and building new drilling platforms is still especially gas hydrate resources. China's oil companiesat preliminary stage, and there are key equipment and should work towards deepwaters while acceleratingtechnology made in Chinaexploration and development of oil and gas in shallow(3) Most equipment for subwater drilling and seaproduction in deepwaters relies on import(4) There is no technology available for safe operation Referencesof submarine pipelines and systems. The static pressure is [1] Jiang Huaiyou, Pan Jiping, Shao Kuilong. Currentextremely high and the temperature is low in deepwaters, State of Worldwide Marine Oil and Gas Exploration[J]which requires a lot on the pipeline strength and flow China Petroleum Enterprise, 2009, 3: 77-79conveying in pipes. So it will directly affect the safe [2] Jiang Huaiyou, Zhao Wenzhi, Qiu Yinan. Currentoperation of submarine gathering systemState of Marine Oil and Gas Resources in the World and(5)Outdated logistics support and supporting facilities Its Exploration[]. China Petroleum Exploration, 2008,could not satisfy the need of ocean exploration. This 27(3): 27-34includes various living and technological support for [3] Ren Keren, Wang Dingya, Zhou Tianming. Currentservice vessels, supply vessels, and survey vesselsState and Development Trends of Marine Oil SubwaterCNoOC has taken deepwater operation as one of the Equipment[]. China Petroleum Machinery, 2008, 36(9)major goals in the future. CNPC plans to build multiple 151-153large-scale deepwater apparatus such as deepwater [4] Zhao Zhengzhang, Zhao Xianzheng Developmentdrilling vessels and pipe-laying and crane, and establish Trends and Their Inspiration of Oversea Deep Offshoreits own deepwater experiments and working fleets in the Oil and Gas Exploration[]. China Petroleum Exploration,coming years. Well LW3-1-I in the Pearl River Mouth 2005, 6: 71-76Basin in South China Sea, with the operating depth of [5] Guo Yongfeng, Zhou Xiaohui, Bai Yuncheng1480m, is China's first one with water depth more than Development and Prospect for Worldwide Deep Sea1000 kilometers. In May 2011, China's first 3,000m- Oilfields[]. Foreign Oilfield Engineering, 2008, 24(12)deep deepwater semi-submersible platform, HYSY-981, 30-31invested by CNOOC, was completed in Shanghai and will [6] Lv Fuliang, He Xunyun, Wu Jinyun, Currentsoon be unlocked for offshore installation and trial runSituation and Tendency of Deepwater Oil and GasBefore. CNOOC has built HYSY-117, a 300.000- Exploration in the World[J]. China Petroleum Exploration,tonnage offshore floating production storage offloading 2007,6: 28-31(FPSO). This indicates that China has edged into the [7] Zhu Haiyan, Liu Qingyou, Wang Guorong. Currentadvanced ranks in the world in terms of design and Status of Natural Gas Hydrate Sampling Device[J]construction of such equipment. China has been in the Natural Gas Industry, 2009, 29(6): 63-66world leading level in both construction speed and quality, [8] Li Qingping. The Situation and Challenges forthanks to the solid basis of China's shipbuilding industry. Deepwater Oil and Gas Exploration and Exploitation inChina. China Offshore Oil and Gas, 2006, 18(2): 130-Suggestions about enhancing China's capacity 33in deep sea exploration9]Zhang Xishun, Li Jingyuan, Zhang Xianghua(1) To keep an eye on the up-to-date technology, Deepwater Petroleum Drilling and p nuetionstrengthen fundamental research, increase investment,Technology[J中国煤化工 n Technologyand construct equipment appropriate for drilling and 2009,31(2):34CNMHGCHINA OIL GASNo.3.2011