New Model of Predicting Remaining Recoverable Reserves and Application in the Oilfield

As a significant inducement during the development of oil and gas,the role of remaining recoverable reserves is more observable especially in the later phase of development of oilfield.Depended on the production decline method in petroleum reservoir engineering,a new model of predicting recoverable and remaining recoverable reserves has been

Review of surfactant-assisted chemical enhanced oil recovery for carbonate reservoirs: challenges and future perspectives

A significant fraction of the conventional oil reserves globally is in carbonate formations which contain a substantial amount of residual oil. Since primary and secondary recovery methods fail to yield above 20%-40%of original oil in place from these reserves, the need for enhanced oil recovery（EOR） techniques for incremental oil recovery has become imperative. With the challenges presented by the highly heterogeneous carbonate rocks,evaluation of tertiary-stage recovery techniques including chemical EOR（c EOR） has been a high priority for researchers and oil producers. In this review, the latest developments in the surfactant-based c EOR techniques applied in carbonate formations are discussed, contemplating the future direction of existing methodologies. In connection with this, the characteristics of heterogeneous carbonate reservoirs are outlined. Detailed discussion on surfactant-led oil recovery mechanisms and related processes, such as wettability alteration, interfacial tension reduction, microemulsion phase behavior, surfactant adsorption and mitigation, and foams and their applications is presented. Laboratory experiments, as well as field study data obtained using several surfactants, are also included.This extensive discussion on the subject aims to help researchers and professionals in the field to understand the current situation and plan future enterprises accordingly.

The “fracture-controlled reserves” based stimulation technology for unconventional oil and gas reservoirs

To solve the problems facing the economic development of unconventional oil and gas, a new concept and corresponding technology system of reservoir stimulation based on "fracture-controlled reserves" are put forward. The "fracture-controlled reserves" stimulation technology is to realize the three-dimensional producing and economic and efficient development of unconventional hydrocarbon resources by forming a fracture system that well matches "sweet spots" and "non-sweet spots". The technical route of the stimulation technology is "three optimizations and controls", that is, control the scope of sand body through optimizing well spacing, control the recoverable reserves through optimizing fracture system, and control the single well production reduction through optimizing energy complement method. The "fracture-controlled reserves" stimulation emphasizes the maximization of the initial stimulation coefficient, the integration of energy replenishment, stimulation and production, and prolonging the re-fracturing cycle or avoiding re-fracturing. It aims at realizing the three-dimensional full producing and efficient development of reservoir in vertical and horizontal directions and achieving the large-scale, sustainable and high profitable development of unconventional oil and gas resources. The stimulation technology was used to perform 20 pilot projects in five typical tight-oil, shale gas blocks in China. The fracturing and producing effects of tight oil improved and the commercial development for shale gas was realized.

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.

Large Oil Reserves Found in Bohai Bay

Exploration teams have found the Bohai Bay Basin of North China may contain 20.5 billion tons of offshore oil reserves, with 9 billion tons already proven, experts said. The remaining 11.5 billion tons need to be further explored. The find indicates that total oil resources in place

Sinopec Adds Brazil Offshore Oil Reserves with Purchase of Galp Unit Stake

According to Bloomberg on November 12, China Petrochemical Corp., Asia’s biggest ref iner, agreed to buy a 30 percent stake in Galp Energia SGPS SA (GALP)’s Brazilian unit, its second invest- ment in offshore oil fields in Latin America’s largest economy in as many years.

Multi-parameter quantitative assessment of 3D geological models for complex fault-block oil reservoirs

In the field of 3 D geologic modeling, researchers often pay more attention to modeling methods and workflows, but neglect the quantitative evaluation of models. If the evaluation is narrowed to the same reservoir type, the comparability and practicality of quantitative assessment will be emerging. The evaluation system should include three parts: data verification, geological understanding and process check. Data verification mainly involves testing the accuracy of local prediction with actual data, and geological understanding is to examine whether the global estimation honors geological principles and prior insights. Process check is also indispensable to avoid occasionality. To this end, we produced a set of assessment criteria, taking complex fault-block sandstone oil reservoir as an example. To be specific, thirteen characteristic parameters were totally selected, setting weights according to their rated importance, formulating three-level evaluation standards in a centesimal system for each characteristic parameter, and obtaining the final assessment based on the cumulative score. The results indicate that such evaluation can not only access the quality of the model objectively and comprehensively, but also identify the aspects in need of improvement through the deduction items.

Microscale comprehensive evaluation of continental shale oil recoverability

This paper targets the shale oil reservoirs of middle to high maturity in four major basins of China,including the Permian Lucaogou Formation of the Jimsar Sag in the Junggar Basin,the Chang 73 Member of the Triassic Yanchang Formation in the Longdong area of the Ordos Basin,the Kong 2 Member of the Paleogene Kongdian Formation in Cangdong Sag of the Bohai Bay Basin,and the Qing 1 Member of the Cretaceous Qingshankou Formation in Changling Sag of the Songliao Basin.The key parameters of the shale oil reservoirs in the four basins,such as reservoirs effectiveness,oil content,crude oil movability,and fracability,have been revealed under identical experimental conditions using the same evaluation technical system,on the basis of technique development and integrated application of multi-scale spatial distribution depiction,effective connectivity calculation,movable oil assessment based on the charging effect,and simulation of fracture propagation during reservoir stimulation.This research overcomes insufficient resolutions of conventional analysis approaches and difficulties in quantitative evaluation,develops the evaluation method for resource recoverability of different types of shale oil,and gains insights into different types of shale oil via comparison.The results of experiments and comparative analysis show that there are significant differences in the endowment of continental shale oil resources in the four major basins in China.Among them,the Lucaogou Formation in the Junggar Basin has more effective shale reservoirs,the Chang 73 sub-member of the Ordos Basin has a comparatively good proportion of movable oil and the Kong 2 Member of the Bohai Bay Basin has the best fracability.These results can provide references and basis for choosing development plans and engineering techniques.

Innovation and practice of petroleum engineering synergetic management for the development of difficult-to-produce reserves

Due to engineering technology and development costs,a considerable amount of proven oil and gas resources in China are difficult to develop,becoming reserves difficult to produce.Based on the successful development of some domestic oil and gas reserves difficult to recover,this article summarizes the"four in one"petroleum engineering synergetic management model to promote the effective development of these reserves.This model draws on the essence of management theories,such as system theory,cybernetics and synergetic theory,and proposes the development idea of value creating and sharing for this type of reserves.By adopting the new management method of mechanism synergy,speciality synergy,process synergy and industrial chain synergy,this model effectively overcomes the decentralization of management responsibility,different management objectives,great risks of engineering and technological innovation,and the large number of uncertain factors in project construction,and can stimulate the vitality and power of active coordination of project participants,to effectively realize the synergetic innovation of engineering technology and synergetic cost reduction of the whole chain,reduction of the balanced oil price of the project,and dispersion of the project investment risk.By adopting this model,a large proportion of difficult-to-produce reserves have been liberated,realizing the effective utilization of the difficult-to-produce oil and gas resources,and making the reserves an important supplement to ensure national energy security.

Develop ment in Eastern Oilfields Tertiary Recovery Techniques

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Effects of Crude Oil Contamination on Soil Physical and Chemical Properties in Momoge Wetland of China

Large oilfields are often coincidentally located in major river deltas and wetlands,and potentially damage the structure,function and ecosystem service values of wetlands during oil exploration.In the present study,the effects of crude oil contamination during oil exploration on soil physical and chemical properties were investigated in marshes of the Momoge National Nature Reserve in Jilin Province,China.The concentrations of total petroleum hydrocarbons in the marsh soil near the oil wells are significantly higher than those in the adjacent control marsh.Soil water contents in oil-contaminated marshes are negatively correlated with soil temperature and are significantly lower than those in the control area,especially in fall.Crude oil contamination significantly increases the soil pH up to8.0,and reduces available phosphorus concentrations in the soil.The concentrations of total organic carbon are significantly different among sampling sites.Therefore,crude oil contamination could potentially alkalinize marsh soils,adversely affect soil fertility and physical properties,and cause deterioration of the marshes in the Momoge National Nature Reserve.Phyto-remediation by planting Calamagrostis angustifolia has the potential to simultaneously restore and remediate the petroleum hydrocarbon-contaminated wetlands.Crude oil contamination affects the soil physical and chemical properties,so developing an effective restoration program in the Momoge wetland is neccesary.

Distribution and potential of global oil and gas resources

Using conventional and unconventional oil and gas resource evaluation methods with play as a unit, this study evaluates the oil and gas geology and resource potential of conventional oil and gas resources and seven types of unconventional resources in the global major oil and gas basins(excluding China). For the first time, resource evaluation data with independent intellectual property rights has been obtained. According to evaluation and calculation, the global recoverable conventional oil resources are 5 350.0×108 t, the recoverable condensate oil resources are 496.2×108 t, and the recoverable natural gas resources are 588.4×1012 m3. The remaining oil and gas 2 P recoverable reserves are 4 212.6×108 t, the reserve growth of oil and gas fields are 1 531.7×108 t. The undiscovered oil and gas recoverable resources are 3 065.5×108 t. The global unconventional oil recoverable resources are 4 209.4×108 t and the unconventional natural gas recoverable resources are 195.4×1012 m3. The evaluation results show that the global conventional and unconventional oil and gas resources are still abundant.

Connotation and strategic role of in-situ conversion processing of shale oil underground in the onshore China

In-situ conversion processing (ICP) of shale oil underground at the depth ranging from 300 m to 3 000 m is a physical and chemical process caused by using horizontal drilling and electric heating technology, which converts heavy oil, bitumen and various organic matter into light oil and gas in a large scale, which can be called"underground refinery". ICP has several advantages as in CO2capture, recoverable resource potential and the quality of hydrocarbon output. Based on the geothermal evolution mechanism of organic materials established by Tissot et al., this study reveals that in the nonmarine organic-rich shale sequence, the amount of liquid hydrocarbon maintaining in the shale is as high as 25%in the liquid hydrocarbon window stage (R o less than 1.0%), and the unconverted organic materials (low mature-immature organic materials) in the shale interval can reach 40%to 100%. The conditions of organic-rich shale suitable for underground in-situ conversion of shale oil should be satisfied in the following aspects, TOC higher than 6%, R o ranging between 0.5%and 1%, concentrated thickness of organic-rich shale greater than 15 meters, burial depth less than 3 000 m, covering area bigger than 50 km2, good sealing condition in both up-and down-contacting sequences and water content smaller than 5%, etc. The shale oil resource in China’s onshore region is huge. It is estimated with this paper that the technical recoverable resource reaches 70-90 billion tons of oil and 60-65 trillion cubic meters of gas. The ICP of shale oil underground is believed to be a fairway to find big oil in the source kitchen in the near future. And it is also believed to be a milestone to keep China long-term stability of oil and gas sufficient supply by putting ICP of shale oil underground into real practice in the future.

Application of New Water Flooding Characteristic Curve in the High Water-Cut Stage of an Oilfield

The oil production predicted by means of the conventional water-drive characteristic curve is typically affected by large deviations with respect to the actual value when the so-called high water-cut stage is entered.In order to solve this problem,a new characteristic relationship between the relative permeability ratio and the average water saturation is proposed.By comparing the outcomes of different matching methods,it is verified that it can well reflect the variation characteristics of the relative permeability ratio curve.Combining the new formula with a reservoir engineering method,two new formulas are derived for the water flooding characteristic curve in the high water-cut stage.Their practicability is verified by using the production data of Mawangmiao and Xijiakou blocks.The results show that the error between the predicted cumulative oil production and production data of the two new water drive characteristic curves is less than the error between the B-type water drive characteristic curve and the other two water drive characteristic curves.It is concluded that the two new characteristic curves can be used to estimate more accurately the recoverable reserves,the final recovery and to estimate the effects of water flooding.

Design of Mooring System for Oil Storage Vessels

The floating oil storage system has been proposed as a new facility for Strategic Petroleum Reserve (SPR) in China. Mooring is one of the key technologies to ensure the safety, reliability, and performance of the oil storage system. This paper describes the concept, analysis, design and reliability of the mooring system. For mooring system design of these oil vessels, analysis is essential of the behavior of the vessel in connection with mooring facilities of nonlinear resilience. A nonlinear mathematical model for analyzing a moored vessel is established and solved. Some results of numerical simulations are presented. Assessment of the safety regarding the mooring system in terms of failure probability is carried out. Another simulation model for calculating the failure probability of the mooring system is proposed. The design parameters that have an influence on the characteristics of the failure probability have been identified. The simulation results,show that the mooring system has an annual reliability value of 0.999998. The proposed simulation method is proved to be effective in quantitative evaluation of the safety of the mooring system for floating oil storage vessels.

The Value Constrained Production Decline Model and Its Application in Reserve Valuation

In the asset valuation of oil and gas reserves, it is discovered that the production decline trend of wells is not very obvious and that it is hard to make a production forecast matching the production history, thus resulting in a significant deviation of oil and gas asset value. For production with a significant fluctuation, the value deviation is also considerable if the matching production, which is predicted with classical decline methods, cannot appropriately reflect the time value distribution of actual production. To mitigate such a deviation, a concept is proposed concerning the value constrained production forecast and the value constrained production decline model is developed. A field case is demonstrated as an application of such a model. The model can significantly decrease the risk in the value deviation of a production decline analysis and be applied to the production forecasts for a single well, well clusters, blocks or field scale, and even for other mining industries.

Low cost development strategy for oilfields in China under low oil prices

By reviewing the challenges in the development of oilfields in China under low oil prices,this study analyzes the root causes of cost rising,put forwards the low cost oilfield development strategy and specific paths to realize the strategy,and predicts the development potential and prospect of oilfields in China.In addition to the low grade of the reservoir and high development maturation,the fundamental reasons of development full cost rising of oilfields in China are as follows:(1)Facing the problem of resources turning poorer in quality,we have built production capacity at a pace too fast before making enough technical and experimental preparation;(2)technical engineering service model leads to high service cost;(3)team of oil development expertise and matched engineering system cannot satisfy the technical requirements of stabilizing oil production,controlling water cut and fine development.To realize development at low cost,the core is to increase economic recoverable reserves.The concrete paths include:(1)to explore the"Daqing oilfield development culture",improve the ability of leaders in charge of development,and inspire potential of staff;(2)to improve the ability of reservoir dynamics control,and implement precise development by following scientific principles;(3)to speed up integration of water flooding and enhanced oil recovery(EOR)and technological upgrading in order to enhance oil recovery;(4)to innovate key techniques in gas flooding and accelerate the industrial popularization of gas flooding;(5)to break the related transaction barriers and create new management models;and(6)to collaboratively optimize strategic layout and cultivate key oil bases.Although oilfield development in China faces huge challenges in cost,the low-cost development strategy will succeed as long as strategic development of mature and new oil fields is well planned.The cores to lower cost are to control decline rate and enhance oil recovery in mature oil fields,and increase single well productivity through technical innovation and improve engineering service efficiency through management innovation in new oil fields.

Production evolution patterns and development stage division of waterflooding oilfields

The continuous growth of recoverable reserves in a waterflooding oilfield has a significant impact on the patterns of production evolution. A new production evolution model is established by improving the Weng Cycle model. With the new model, the statistical correspondence between the production decline stage and the reserve-production imbalance is clarified,and the correlation of water cut with the recovery percent of recoverable reserves is discussed, providing quantitative basis of reservoir engineering for dividing development stages of oilfield and defining mature oilfields. According to the statistics of oilfields in eastern China, the time point corresponding to the reserve-production balance coefficient dropping to less than 1dramatically is well correlated the beginning point of production decline, thus the time when the reserve-production balance coefficient drops dramatically can be taken as the initiation point of production decline stage. The research results show that the water cut and the recovery percent of recoverable reserves have a good statistical match in the high water cut stage, and it is more rational to take both the start point of production decline stage and the water cut of 90%(or the recovery percent of recoverable reserves of 80%) as the critical criteria for defining a mature oilfield. Five production evolution patterns can be summarized as follows: growth–peak plateau–stepped decline, growth–stepped stabilizing–stepped decline, growth–stepped stabilizing–rapid decline, growth–peak plateau–rapid decline, and growth–continuous decline.

基于投影寻踪模型的特高含水油藏剩余油可采潜力评价方法

影响特高含水油藏剩余油可采潜力的因素极其复杂,且各因素的影响程度差异明显,常规方法多以剩余油饱和度或剩余油储量丰度等单一指标评价剩余油潜力,难以有效指导特高含水油藏剩余油挖潜。在充分考虑特高含水油藏剩余油可采潜力影响因素的基础上,综合表征储层非均质性、剩余油可采储量规模、水淹状况以及油水分流能力的差异,构建了特高含水油藏剩余油可采潜力量化评价指标体系,并考虑不同指标对剩余油可采潜力控制程度的差异,将加速遗传算法与投影寻踪模型相结合来确定各评价指标的客观权重,从而构建了剩余油可采潜力指数,形成特高含水油藏剩余油可采潜力量化评价新方法。以渤海Q油田南区主力产层NmIL砂体为例,开展特高含水油藏剩余油可采潜力量化评价,结果表明,新方法可综合表征不同区域位置的储层物性、可采储量丰度和油水分流能力对剩余油可采潜力的影响,实现了主力产层NmIL砂体剩余油可采潜力分布的差异化定量评价,优势可采潜力区域刻画明显,将其作为NmIL砂体下一步井网加密调整潜力区域,以精准指导加密水平井的部署,为特高含水油藏剩余油挖潜提供了一种全新的分析方法与思路。