Origin of condensate oil and natural gas in Bozhong 19-6 gas field,Bohai Bay Basin

The discovery of the Bozhong 19-6 gas field has opened a new frontier for deep gas exploration in the Bohai Bay Basin,with a great potential for further gas exploration.However,poor understanding of oil and gas origin has been limiting the exploration progress in this area.To clarify the origin of condensate oil and gas in Bozhong 19-6 gas field,this study adequately utilized the organic geochemical analysis data to investigate the composition and geochemical characteristics of condensate oil and natural gas,and analyzed the relationship between condensate oil and the three sets of source rocks in the nearby subsags.Results show that the lighter components dominate the condensate oil,with a forward type predominance.The parent material of crude oil was primarily deposited in a shallow,clay-rich,low-salinity,weakly reducing aquatic environment.The condensate and natural gas have similar parent source characteristics and maturity,with Ro ranging from 1.4%to 1.6%.Both are products of high maturity stage,indicating that they are hydrocarbon compounds produced by the same group of source rocks in the same stage.Oil-sources correlation shows that condensate oil and gas mainly originate from the source rocks of the third member of Shahejie Formation in the nearby subsags of the Bozhong 19-6 structural belt.

Formation conditions and exploration direction of large natural gas reservoirs in the oil-prone Bohai Bay Basin, East China

The Bohai Bay Basin is a typical oil-prone basin, in which natural gas geological reserves have a small proportion. In this basin, the gas source rock is largely medium-deep lake mudstone with oil-prone type Ⅱ2-Ⅱ1 kerogens, and natural gas preservation conditions are poor due to active late tectonic movements. The formation conditions of large natural gas fields in the Bohai Bay Basin have been elusive. Based on the exploration results of Bohai Bay Basin and comparison with large gas fields in China and abroad, the formation conditions of conventional large-scale natural gas reservoirs in the Bohai Bay Basin were examined from accumulation dynamics, structure and sedimentation. The results show that the formation conditions of conventional large natural gas reservoirs in Bohai Bay Basin mainly include one core element and two key elements. The core factor is the strong sealing of Paleogene "quilt-like" overpressure mudstone. The two key factors include the rapid maturation and high-intensity gas generation of source rock in the late stage and large scale reservoir. On this basis, large-scale nature gas accumulation models in the Bohai Bay Basin have been worked out, including regional overpressure mudstone enriching model, local overpressure mudstone depleting model, sand-rich sedimentary subsag depleting model and late strongly-developed fault depleting model. It is found that Bozhong sag, northern Liaozhong sag and Banqiao sag have favorable conditions for the formation of large-scale natural gas reservoirs, and are worth exploring. The study results have important guidance for exploration of large scale natural gas reservoirs in the Bohai Bay Basin.

Bargaining strategy of oil companies in international oil and gas development Projects-Based on a bilateral bargaining model

Bargaining between the host country and oil companies is very common to international oil and gas development projects.The existence of information asymmetry gives the host country an endogenous bargaining advantage.Foreign oil companies might change their unfavorable negotiating position by changing the order of bidding and adjusting bidding strategies.This paper introduces both factors into a bilateral bargaining model to study the impact of information asymmetry and bidding order on the strategy and equilibrium returns of oil companies.According to the ownership of the right to bid first,two scenarios are designed for the model to compare the equilibrium returns of the host country and oil companies.The results show that:1)There is a first-mover advantage in the process of bilateral bidding,so oil companies better bid first;2)The information asymmetry will lead to a higher nominal income ratio of oil companies and a lower nominal income ratio of the host country,but it doesn’t affect the total income ratio at all.

Assessment of Uinta Basin Oil and Natural Gas Well Pad Pneumatic Controller Emissions

In the fall of 2016, a field study was conducted in the Uinta Basin Utah to improve information on oil and natural gas well pad pneumatic controllers (PCs) and emission measurement methods. A total of 80 PC systems at five oil sites (supporting six wells) and three gas sites (supporting 12 wells) were surveyed, and emissions data were produced using a combination of measurements and engineering emission estimates. Ninety-six percent of the PCs surveyed were low actuation frequency intermittent vent type. The overall whole gas emission rate for the study was estimated at 0.36 scf/h with the majority of emissions occurring from three continuous vent PCs (1.1 scf/h average) and eleven (14%) malfunctioning intermittent vent PC systems (1.6 scf/h average). Oil sites employed, on average 10.3 PC systems per well compared to 1.5 for gas sites. Oil and gas sites had group average PC emission rates of 0.28 scf/h and 0.67 scf/h, respectively. This difference was due in part to differing site selection procedures used for oil and gas sites. The PC system types encountered, the engineering emissions estimate approach, and comparisons to measurements are described. Survey methods included identification of malfunctioning PC systems and emission measurements with augmented high volume sampling and installed mass flow meters, each providing a somewhat different representation of emissions that are elucidated through example cases.

Erratum to “Assessment of Uinta Basin Oil and Natural Gas Well Pad Pneumatic Controller Emissions” [Journal of Environmental Protection, 2017, 8, 394-415]

In the fall of 2016, a field study was conducted in the Uinta Basin Utah to improve information on oil and natural gas well pad pneumatic controllers (PCs) and emission measurement methods. A total of 80 PC systems at five oil sites (supporting six wells) and three gas sites (supporting 12 wells) were surveyed, and emissions data were produced using a combination of measurements and engineering emission estimates. Ninety-six percent of the PCs surveyed were low actuation frequency intermittent vent type. The overall whole gas emission rate for the study was estimated at 0.36 scf/h with the majority of emissions occurring from three continuous vent PCs (1.1 scf/h average) and eleven (14%) malfunctioning intermittent vent PC systems (1.6 scf/h average). Oil sites employed, on average 10.3 PC systems per well compared to 1.5 for gas sites. Oil and gas sites had group average PC emission rates of 0.28 scf/h and 0.67 scf/h, respectively. This difference was due in part to differing site selection procedures used for oil and gas sites. The PC system types encountered, the engineering emissions estimate approach, and comparisons to measurements are described. Survey methods included identification of malfunctioning PC systems and emission measurements with augmented high volume sampling and installed mass flow meters, each providing a somewhat different representation of emissions that are elucidated through example cases.

Significant Increase of Oil and Natural Gas Reserves throughout 2013

China＇s Ministry of Land and Resources announced on 27th February 2014 that proven reserves of oil, natural gas and coal continued to increase significantly, and that their production shows a steady increase. This greatly improves China＇s support capacity of fossil fuel resources.

Opportunities and Risks of Natural Gas Investment in China under the Circumstance of Low Oil Prices

After more than 30 years of rapid growth, the Chinese economy has entered the "new normal" of moderately high growth. Due to the effects of multiple factors, the international oil price has remained consistently low. The low oil price has exerted critical effects on international natural gas investment. At the same time, the market-oriented price mechanism of natural gas in China is gradually taking shape; the concept of low carbon development is widely advocated; and the use of natural gas gains popularity in the city. Such factors provide great opportunities for investment in the natural gas market of China, including boiler coal-to-gas transformation, natural gas distributed energy and natural gas vehicles. However, risks also exist, such as the lower competitiveness of natural gas, its excess production capacity and dwindling consumption in some gas consumption industries, an insufficient driving force for facilitating the coal-to-gas transformation of industrial fuel users, reverse substitution of "coal in place of gas" in some enterprises, nontransparent costs of the downstream link of the natural gas price chain, and mismatches and nonsynchronous adjustments in natural gas prices and electricity prices.

Analysis of the Strategies of the 'Replacement of Coal and Oil' with Natural Gas in Sichuan Province

Sichuan Province boasts rich clean energy such as natural gas and hydroelectricity. In order to realize the blueprint of a beautiful China, it is both necessary and feasible for Sichuan Province to ＂replace coal and oil＂ with natural gas. Based on the actual situation of Sichuan Province, through research and investigation, rational thinking and summarization, this paper analyzes the current demand for energy supply in Sichuan, defines the development goals and ideas concerning Sichuan＇s ＇replacement of coal and oil＂ with natural gas, examines the action plan related to such replacement and puts forward relevant policies and suggestions.

Evaluation and re-understanding of the global natural gas hydrate resources

Natural gas hydrate(NGH)has been widely considered as an alternative to conventional oil and gas resources in the future energy resource supply since Trofimuk’s first resource assessment in 1973.At least 29 global estimates have been published from various studies so far,among which 24 estimates are greater than the total conventional gas resources.If drawn in chronological order,the 29 historical resource estimates show a clear downward trend,reflecting the changes in our perception with respect to its resource potential with increasing our knowledge on the NGH with time.A time series of the 29 estimates was used to establish a statistical model for predict the future trend.The model produces an expected resource value of 41.46×1012 m3 at the year of 2050.The statistical trend projected future gas hydrate resource is only about 10%of total natural gas resource in conventional reservoir,consistent with estimates of global technically recoverable resources(TRR)in gas hydrate from Monte Carlo technique based on volumetric and material balance approaches.Considering the technical challenges and high cost in commercial production and the lack of competitive advantages compared with rapid growing unconventional and renewable resources,only those on the very top of the gas hydrate resource pyramid will be added to future energy supply.It is unlikely that the NGH will be the major energy source in the future.

Research progress and challenges of natural gas hydrate resource evaluation in the South China Sea

As an efficient clean energy,natural gas hydrate(NGH)has become a hot topic in recent researches.Since1990 s,China has made great achievements and progress in NGH exploration in the South China Sea(SCS),including determination of the favorable distribution areas and favorable strata thickness,identification of the dual source for accumulation,evaluation of the prospective gas contents,verification of the widespread existence,and confirmation of the technical recoverability of NGH resources.However,there are three major challenges in the NGH studies.First,all the 24 national key and major projects in the SCS focused on trial production engineering and geological engineering in the past 20 years,while 8 of the 10 international NGH research projects focused on resource potential.Second,resource evaluation methods are outdated and some parameter selection are subjective.Third,the existing resource evaluation results are low-level with a great uncertainty,and cannot be used to guide NGH exploration and production or strategic research.To improve the evaluation of NGH resources in the SCS,future researches should focus on four aspects:(1)improve the research on the criterion of the objective existence of NGH and the method of prediction and evaluation;(2)apply new theories and methods from the global NGH research;(3)boost the research on the difference and correlation of the conditions of hydrocarbon migration and accumulation in different basins;(4)innovate the theory and method of NGH resource potential evaluation.

The potential of domestic production and imports of oil and gas in China:an energy return on investment perspective

Concerns about China’s energy security have escalated because of the country’s high dependency on oil and gas imports, so it is necessary to calculate the availability of domestic oil and gas resources and China’s ability to obtain foreign energy through trade. In this work,the calculation was done by using the energy return on investment（EROI） method. The results showed that the EROIstnd（i.e., standard EROI） of China’s oil and gas extraction decreased from approximately 17.3：1 in 1986 to 8.4：1 in 2003, but it increased to 12.2：1 in 2013. From a company-level perspective, the EROIstnddiffered for different companies and was in the range of（8–12）：1. The EROI2,d（EROI considering energy outputs after processed and direct energy inputs） for different companies was in the range of（3–7）：1. The EROI of imported oil（EROIIO）declined from 14.8：1 in 1998 to approximately 4.8：1 in 2014, and the EROI of imported natural gas（EROIING）declined from 16.7：1 in 2009 to 8.6：1 in 2014. In 2015, the EROIIO and EROIING showed a slight increase due to decreasing import prices. In general, this paper suggests that from a net energy perspective, it has become more difficult for China to obtain oil and gas from both domestic production and imports. China is experiencing an EROI decline, which demonstrates the risk in the use of unsustainable fossil resources.

Distribution and resource evaluation of natural gas hydrate in South China sea by combing phase equilibrium mechanism and volumetric method

China Geological Survey conducted the second trial production of natural gas hydrate(NGH)in the Shenhu Area in South China Sea(SCS)from 2019 to 2020.Compared with the first trial production in 2017,the second trial showed significantly increased daily gas production and total gas production,and removed some technical obstacles for large-scale NGH resource developments in the SCS.However,current NGH resource evaluation in the SCS is still at the stage of prospective gas content assessment,which is unable to guide further NGH exploration and development.This study utilized the hydrate phase balance to delineate the NGH distribution range and effective thickness and volumetric method to evaluate NGH resource.Based on the latest exploration and production data from the Shenhu Area,Monte Carlo simulation was performed to calculate the NGH resource amount with different probabilities.By assuming a 50%cumulative probability,the in-situ NGH resources in the SCS was estimated to be11.7×10^(12)m^(3) and the recoverable NGH resources was 2.8×10^(12)m^(3).These results will provide a more reliable resource basis for China to formulate comprehensive development strategies for oil and gas exploration in the SCS.

Investigation of flue gas water-alternating gas (flue gas–WAG) injection for enhanced oil recovery and multicomponent flue gas storage in the post-waterflooding reservoir

Flue gas fooding is one of the important technologies to improve oil recovery and achieve greenhouse gas storage.In order to study multicomponent fue gas storage capacity and enhanced oil recovery(EOR)performance of fue gas water-alternating gas(fue gas-WAG)injection after continuous waterfooding in an oil reservoir,a long core fooding system was built.The experimental results showed that the oil recovery factor of fue gas-WAG fooding was increased by 21.25%after continuous waterfooding and fue gas-WAG fooding could further enhance oil recovery and reduce water cut signifcantly.A novel material balance model based on storage mechanism was developed to estimate the multicomponent fue gas storage capacity and storage capacity of each component of fue gas in reservoir oil,water and as free gas in the post-waterfooding reservoir.The ultimate storage ratio of fue gas is 16%in the fue gas-WAG fooding process.The calculation results of fue gas storage capacity showed that the injection gas storage capacity mainly consists of N_(2) and CO_(2),only N_(2) exists as free gas phase in cores,and other components of injection gas are dissolved in oil and water.Finally,injection strategies from three perspectives for fue gas storage,EOR,and combination of fue gas storage and EOR were proposed,respectively.

Data Strategies-Lessons and Examples from the Frontier Lines of an International Oil and Gas Company

Data strategies and tactics used to create and promulgate robust databases across a wide organization are subject to a number of constraints and challenges.This presentation reviews lessons learned from one company in the oil and gas industry,and illustrates how that company met and overcame challenges during the database design and implementation phases.

Problems and Strategies of China’s Natural Gas Industry

Although significant progress in China＇s natural gas industry has been made since the adoption of the ＂Eighth Five-Year Plan＂（from 1991 to 1995）, some problems still exist in the aspects of gas resources, exploitation, utilization and macromanagement, and hinder a further development of the natural gas industry. A series of strategies for solving the problems was put forward, including accurate orientation of the natural gas industry, strengthening the construction of gas transmission and distribution networks, comprehensive exploitation policies for ＂integration of up-and-downstream＂, government-supported gas-preferential policies, construction of the gas market frameworks and devoting strong effort to the new market development.

Oil and Gas Supply and Demand in China and Its Development Strategy

The paper makes a comprehensive prediction of China＇s future demand for oil and gas with two methods, i.e. the prediction method based on the demand for individual oil and gas products and the method for predicting the total demand. According to the demand prediction of, and the historical data on, the oil and gas consumption, we conduct an analysis of the oil and gas consumption trends, which can be described as six different development periods. On the other hand, the paper makes a comprehensive analysis of the domestic oil and gas resources and, on this basis, makes a basic prediction of the domestic output of oil and gas. The supply and demand situation is also analyzed. By using the SWOT analysis method, the paper puts forward the development strategies for China＇s oil and gas industry and gives some related strategic measures.

Research on the Control Strategy of Variable Nozzle Turbocharger for Natural Gas Engine

A variable nozzle turbocharger （VNT） was applied to a 2.2-liter L4 natural gas engine,and a VNT control system was designed to operate it.Based on VNT matching test results,a VNT control strategy was studied,in which VNT adjustment is carried out through pre-calibrated VNT handling rod position,combined with a closed-loop target boost pressure feedback using proportional-integral-derivative（PID） algorithm.Experimental results showed that the VNT control system presented in this thesis can lead to optimized performance of VNT,increase engine volumetric efficiency over a wide speed range,improve engine dynamic characteristics and upgrade economic performance.

Stability analysis of seabed strata and casing structure during the natural gas hydrates exploitation by depressurization in horizontal wells in South China Sea

Natural gas hydrates(NGHs)are a new type of clean energy with great development potential.However,it is urgent to achieve safe and economical NGHs development and utilization.This study established a physical model of the study area using the FLAC^(3D) software based on the key parameters of the NGHs production test area in the South China Sea,including the depressurization method,and mechanical parameters of strata,NGHs occurrence characteristics,and the technological characteristics of horizontal wells.Moreover,this study explored the law of influences of the NGHs dissociation range on the stability of the overburden strata and the casing structure of a horizontal well.The results are as follows.With the dissociation of NGHs,the overburden strata of the NGHs dissociation zone subsided and formed funnelshaped zones and then gradually stabilized.However,the upper interface of the NGHs dissociation zone showed significant redistribution and discontinuity of stress.Specifically,distinct stress concentration and corresponding large deformation occurred in the build-up section of the horizontal well,which was thus prone to suffering shear failure.Moreover,apparent end effects occurred at the end of the horizontal well section and might cause the deformation and failure of the casing structure.Therefore,it is necessary to take measures in the build-up section and at the end of the horizontal section of the horizontal well to prevent damage and ensure the wellbore safety in the long-term NGHs exploitation.

Deepening Oil and Gas Cooperation in Central Asia Against the Background of the Belt and Road Initiative

Energy cooperation is an important part of building the Belt and Road,and Central Asia is the core area of oil and gas cooperation on the Belt and Road route.As one of the first enterprises to“go global”,CNPC has made positive progress in oil and gas cooperation with Belt and Road countries.Exploring oil and gas cooperation in Central Asia in the new situation is of great practical significance for jointly building the Belt and Road,promoting regional cooperation and ensuring China's energy safety.