Recoverable Reserves Research Articles

Establishment and application of prediction model of natural gas reserve and production in Sichuan Basin

Research on predicting the growth trend of natural gas reserves and production will help provide a scientific basis for natural gas exploration and development. The metabolically improved modified weight coefficient GM(1,n) method is applied to the multi-cycle Hubbert model to predict the trend of new proven natural gas reserves in the Sichuan Basin. The ultimate recoverable reserves (URR) is introduced as a boundary condition in the production-time series to predict the natural gas production growth. The research results show that: (1) The annual newly added proven natural gas reserves of the Sichuan Basin maintain a multi-cycle growth trend, which will reach the peak reserves in 2034, at which time the proven rate of natural gas will reach 36%. (2) Based on the predicted results of proven reserves, the final recoverable reserves of natural gas are estimated to be 5.25-5.75times {10}^{12}{m}^{3}. The production in 2035 will reach 750-810times {10}^{8}{mathrm{m}}^{3}/mathrm{a}, and production will grow rapidly. The exploration and development of natural gas in the basin will be prospective for a long time.

DYNAMICS OF OIL PRODUCTION FROM HARD RESERVES IN RUSSIA

The article presents a comprehensive study of the current state and development prospects of hard-to-recover reserves. The role of hard-to-recover reserves in the structure of the crude oil base by categories of reserves and federal districts, as well as on the shelf of the Russian Federation is considered. The analysis of industry-wide trends in the reproduction of the mineral resource base with differentiation by deposits and companies-subsoil users is carried out. The issues of the current state of the volume of financing for geological exploration and the cost of preparing hydrocarbon reserves have been investigated. The dynamics of the distribution of recoverable oil reserves, volumes and efficiency of geological exploration at fields discovered in recent years have been analyzed. The characteristics and dynamics of production of certain categories of hard-to-recover oil by region have been investigated.

Study On Water Injection Effect of New Reservoir For Petroleum Energy Development

Oilfield has gone through the stages of self injection production, water injection development and three times of chemical agent injection development. At present, it has entered the late development stage of high water cut, and the production and new exploration reserves have decreased significantly. As a potential resource of high water cut later development, SA0 formation reservoir has a certain oil and gas abundance. However, because of its poor physical properties and strong water sensitivity, SA0 formation reservoir in Oilfield has great difficulties in water injection development. This set of reservoir was not developed in the early development of Oilfield. With the improvement of development technology and the increasing demand of recoverable reserves, the development of SA0 formation reservoir becomes more and more important. However, there is no in-depth study on the specific characteristic parameters of the reservoir and the feasibility of water injection development, which restricts the development of this set of reservoir. Therefore, this paper explores the feasibility of waterflooding development of lithologic and physical properties of SA0 formation reservoir in Development Zone. Laboratory experiments and field practice show that SA0 formation reservoir is a low permeability and highly sensitive reservoir. 3% concentration of anti swelling agent can effectively inhibit the expansion and migration of clay minerals, and play the purpose of protecting the reservoir. In the field test, through adding clay stabilizer to perforate and complete the well with flow limiting method, a high liquid production capacity has been achieved. At the initial stage, the average daily oil production of a single well is more than 1.50t. The production performance of oil wells is quite different, the liquid production layers are concentrated, and most of them are dry layers. A certain understanding has been obtained in the waterflooding development of SA0 formation in development zone of Oilfield.

Study of fine tapping potential of poor reservoirs in late stage of high water cut

At present, the oilfield development has entered the late stage of high water cut, and the exploitation objects have been changed to the second and third types of oil layers. The distribution of remaining oil is highly fragmented and complex, and the exploitation difficulty is gradually increasing. In view of a series of geological characteristics of Development Zone A, such as “numerous layers, complex reservoirs, severe phase transition and high viscosity”, the potential tapping technologies of Class II and Class III reservoirs, such as combination of two and three and ASP flooding, have been carried out one after another. In order to further enhance oil recovery and increase recoverable reserves, a large number of fracturing measures have been implemented to increase oil production. In view of the fact that it is more and more difficult to select wells and layers by this measure, we combine the results of fine reservoir description with dynamic data, take Block B as the investigation object, establish the potential pool of sedimentary unit-level measures, recognize the potential distribution of 82 different sedimentary units, clarify the target units of potential tapping measures, and finally explore relatively perfect ways and means to optimize fracturing well layers, and strive to achieve targeted adjustment and accurately tap potential. At present, in the early stage of fracturing in this area, the average daily oil increase of a single well is 7.9 tons, and the above practices also provide empirical reference and guidance for other similar blocks.

Dynamic Interference Behaviors of Arbitrary Multilayer Commingling Production in Heavy Oil Reservoirs with Water Flooding.

To obtain sustainable economical oil production and recovery of investment, some oil fields adopted the strategy of multilayer commingling production at an early stage. This leads to interlayer interference and losing part of the recoverable reserves. In this paper, dynamic interference behaviors of arbitrary multilayer commingling production in heavy oil reservoirs are analyzed. Based on the non-Darcy flow equation, the Buckly–Leverett equation, and the material balance equation, a mathematical model of arbitrary multilayer commingling production is obtained. Oil and water relative permeability, saturation, and bottom hole flow pressure microelement and the iteration method are employed to solve the mathematical model in the time domain. The new model is verified by comparing the results from the typical black oil model using the Darcy law. The sensitivity analysis of critical parameters on interference behaviors, such as permeability, oil viscosity, effective drainage boundary, and voidage replacement ratio, is carried out. The model obtained in this paper can be used for oil and liquid productivity analysis during the overall process of commingling production and extended to be applied in numerical experiments with different combinations of typical parameters as well.

Prospect of marine natural gas hydrate stimulation theory and technology system

The key to realize the commercial production of natural gas hydrate (NGH) is to increase theNGH productivity significantly in the scale of magnitude. Whether NGH production can be commercialized depends on two aspects. The first is whether the in-situ recoverable reserves are large enough to support the basic production period for commercial production. The second is whether the average productivity can reach the standard for commercial production. In this paper, we will analyze mainly about the potential stimulation technologies for NGH development, and discuss about the basic principles, the evaluation methods, and the technical bottlenecks for NGH production and stimulation. The results indicate that the main mechanisms for increasing theNGH productivity are in three respects, namely enlarging the drainage area, increasing the NGH dissociation efficiency, and improving the seepage conditions. With complex-structure wells and multiple-well patterns, combined with novel production methods and/or reservoir stimulation technologies, the NGH productivity can be increased greatly. Particularly, the complex-structure wells and well patterns are very important for increasing NGH productivity. With complex-structure wells and well patterns, combined with heat injection and/or reservoir stimulation, NGH productivity can be increased on a magnitude scale. Currently, in fundamental researches, there are some technical bottlenecks for the studies of NGH production, mainly in sample preparation, simulated reservoir monitoring, and mechanical coupling technologies. Therefore, it is suggested that the study focuses should be on the above technical bottlenecks during the basic research on how to increase the NGH productivity. It is concluded that the combined application of complex-structure wells (horizontal wells and multi-lateral wells), well-pattern production models (with multi-cluster/group well production), the novel production methods (mainly thermal stimulation, together with depressurization), and reservoir stimulation technologies (hydraulic fracturing) are the keys to increase NGH productivity in the scale of magnitude.

Classification of residual recoverable and non-recoverable oil reserves by the reservoir complexity index (RCI)

The paper considers a new engineering analytical tool for express oil reserves assessment. Proposed method is based on classifying oil reserves by complexity – reservoir complexity index (RCI). It allows to optimize the development system and form a well interventions program.
 The method is suggested to use three main parameters for development complexity estimation: reservoir permeability, start watercut (which contains the parameters of the curve of relative permeability, saturation and viscosity) and geological heterogeneity (pattern efficiency).
 An economic estimation of the well profitability is carried out by calculating PV UDC indicator (unit development cost, CAPEX / total oil production). The advantages of this indicator is that it allows to determine the economic attractiveness and does not require macro parameters and costs for the building well pads
 Due to the economic assessment and well ranking, it is possible to obtain profitable well pads and select candidates for sidetracking.
 The novelty of the work lies in the use of an updated methodology for the reservoir complexity index estimation for the remaining recoverable reserves classification.
 As a result, high-quality tool is created that integrates RCI and economic model. It is aimed for solving reservoir engineering problems and increasing the project cost
 The proposed method can be applied to other fields with minor modifications.

Quantification of recoverable oil reserves in the S6, S7 and S8 sands, in the Sigmoilina zone, at the Jusepin field in the Orinoco oil and gas basin, Venezuela

Relevance of the work. Quantifying these oil reserves allows Venezuela to lead the ranking as the country with the largest oil reserves worldwide Purpose of the work. Is related to the need of quantification in the recoverable oil reserves in the field of Husepin (Monagas state, Venezuela) for the oil industry. The methodology of the research. The La Pica 01 Field is made up of 509 wells, of which 49 wells were used to elaborate the correlations, since they have spontaneous potential and resistivity curves. For each well, the tops and bases of the units were determined by analyzing the behavior of the electrical responses of each of the sands, applying the basic concepts of stratigraphy, as well as a detailed compilation of all the information that corresponds to the wells that form part of the study to obtain a standard record that contains all the favorable data and be able to carry out the correlations. Research results. In the S6 sand, 4 oil deposits were found and an Original Oil In Place of 15,875.32 thousands of normal barrels and recoverable reserves of 2,857. 5576 thousands of normal barrels were estimated. For S8 sand, 5 oil fields were defined and an Original Oil In Place of 25,940.86 thousands of normal barrels and recoverable reserves of 4,669. 3548 thousands of normal barrels were estimated. Original Oil In Place was not calculated in the S7 sand because it has no deposits. Recommendations. Review the production history and verify which wells can be re-incorporated into an oil extraction plan and Submit the reserves of the study fields to the Ministry of Popular Power for Energy and Petroleum (MENPET) taking into account the results obtained in this investigation. Conclusions. 4 oil deposits were found in the S6 sand and 5 oil deposits were found in the S8 sand and each of them were with stratigraphic limits, structural limits and fluid contact. No oil deposits were found in the S7 sand, although records have been taken in the northwest of the field show thicknesses of ANP at this stratigraphic level. Keywords: oil reserves, Orinoco basin, Sigmoilina zone, well, deposit.

Sidorsky deposit of construction sands in the Volgograd region

Relevance of the research. Construction sands are the largest functional group of sands widely used in construction industry. This natural material is one of the most demanded for the production of manufactured products in the construction industry of the region. Purpose of the researchis to study the engineering-geological conditions of construction sands deposit for the production of the manufactured products of OAO Sebryakovsky plant of asbestos-cement products, as well as for construction organizations of the region. Research methods. Based on the analysis of extensive collection materials using laboratory and statistical methods, as well as the results of additional research, the physical-geographical, engineering-geological and technogenic conditions of the study area were examined. Results and their application. The useful stratum of the deposit is composed of Upper Quaternary alluvial sands, the average thickness of which is 8.6 m, penetrated thickness is up to 12.3 m. Overburden within the study area is represented by the soil-vegetation horizon – up to 0.2 m. The extracted raw materials are used in the production of mortars, which is confirmed by tests of a cement-sand grout, and as a filler in fine-grained concrete. The reserves of the deposit are calculated in categories A + B + C1 in the amount of 2313.2 thousand m3. The development of the deposit is recommended by the open method. Explored and recoverable reserves will ensure the operation of the enterprise with an annual demand of 100 thousand m3 per year for a period up to 2030. Conclusions. Based on the results of the studies, it should be noted that the Sidorsky deposit of construction sands is assessed as profitable and competitive in relation to the exploited deposits of sand in the Volgograd region.

Water scarcity footprint assessment for China's shale gas development

As the largest holder of shale gas resource estimates, China is actively promoting its shale gas development to steer its transitions to a low carbon energy system. The production of shale gas usually needs a large amount of water. According to our estimates, the direct water consumption is about 9700–37600m3/well, and the indirect water consumption is around 32,400–71,100 m3/well. Such a large amount of water consumption could have a serious impact on local human and ecosystem water consumption since China is a country with scarce and unevenly distributed water resources. Water scarcity footprint (WSF) of shale gas production in Chinese provinces is assessed to understand the impacts of shale gas production on local water consumption for other sectors. The results show that the average water pressure for shale gas production in China is higher compared with that of the U.S.. The average WSF in China is 16,574 m3world. eq/106m3 gas while the WSF in the Barnett shale region in the U.S. is only around 2000 m3world. eq/106m3 gas. 13 of 31 provinces have even higher WSF than the national average, in which the amount of shale gas resources accounts for about 20% of China's total. Shale gas exploitation in these 13 provinces might not be suitable or must be cautious from the perspective of WSF. The remaining 18 provinces have lower WSFs than the national average. A sustainable way for extracting shale gas in these 18 provinces needs to comprehensively consider WSF, the scale and speed of exploitation and the amount of local shale gas recoverable reserves.

Research on Von Bertalanffy model and its application for predicting recoverable reserves and production of oilfield

Water drive type curves are simple, convenient and practical in reservoir engineering, which is widely used in reservoir production performance analysis. However, the commonly used water drive type curve can only draw one curve between water cut and recoverable reserves recovery degree, which greatly limits the application range of water drive curve. At the same time, the fitting of straight line section of water drive type curve is often affected by artificial selection, and the error is large. In order to better describe and reflect the rising law of water cut in different type reservoirs, the new water drive type curve is established, and the relationships between water cut and cumulative production, water cut and recovery degree of recoverable reserves are derived. Through MATLAB software programming and multi parameter fitting method, the parameters in the new water drive type curve can be easily calculated. The f w-R * curve shape of the new model includes convex curve, concave curve and S-shape curve. The new water drive type curve is applied to two actual reservoirs. The new curve fits well with the low water cut stage of the Baolang oilfield, and the error is small, which can be used to predict the future production performance of the oilfield. At the same time, the new water drive type curve is consistent with the change trend of the whole production stage of the Saertu oilfield, and the error is small, too. which can be used for the prediction of the whole production period and high water cut stage of the reservoir. The new model expands the application range of water drive type curve and provides reference for production performance prediction of other similar oilfields.

Development of production data analysis models for multi-well gas condensate reservoirs

Production data Analysis (PDA) is a crucial step to determine the recoverable reserve and predict the future performance of the reservoir. Moreover, using these data for a long period which covers transient and pseudo steady state conditions, will result to a great insight of reservoir behavior. One of the challenges of gas condensate reservoirs is well-deliverability determination. All techniques and models for evaluation of reservoir performance assume the constant well drainage area and single well production. The drainage area of the wells in a multi-well reservoir is affected by the interference effect of the wells. Hence, the prediction of well performance by conventional models, assuming constant well drainage area is not applicable in this case. An overall outline of this study is to propose an analytic technique to distinguish the well performance in a multi-well system in gas condensate reservoirs. Moreover, theoretic perception of pseudo steady state models and dynamic material balance for developed model is presented.With the intension of ascertaining the accuracy of proposed methodology, result of this approach is compared with commercial compositional simulator. The results ensure the accuracy of its application in multi-well gas condensate reservoirs.

A novel artificial intelligence automatic detection framework to increase reliability of PLT gas bubble sensing

Production logging tools (PLTs) and formation testing, even in logging while drilling (LWD) conditions during underbalanced drilling, are key technologies for assessing the productivity potential of a gas well and therefore to maximize recovery. Gas bubble detection sensors are key components in determining the fluid phases in the reservoir and accurately quantify recoverable reserves, optimize well placement, geosteering and to qualify the production ability of the well. We present here a new nonlinear autoregressive - breakdown artificial intelligence (AI) detection framework for PLT gas bubble detection sensors that categorize in real-time whether and which sensors become unreliable or have broken down during the logging measurements. AI tools allow the automatization of this method that is critical during data quality control of post-drilling PLT, but it is essential when the measurements are performed in LWD as data assessment and processing need to occur in real-time. This AI framework was validated on both a training and testing dataset, and exhibited strong classification performance. This method enables accurate real-time breakdown detection for gas bubble detection sensors.

Shale gas: Will it become a new type of clean energy in China? — A perspective of development potential

Shale gas, with its low carbon and green characteristics, has attracted a considerable amount of attention in the development of global clean energy. Analyzing the development potential and prospects of shale gas has great significance for strengthening energy security while reducing carbon emissions in China. Based on the current development status, this paper explores the exploitation potential of shale gas development in China from the five main aspects of Porter’s diamond model and proposes a future development strategy. After careful analysis, several discoveries are made. First, the recoverable reserves of shale gas in favorable areas in China have reached 2.18 × 104 billion cubic meters (bcm), but the current proved rate of shale gas is only 4.79%, which indicates its vast development potential. Second, approximately 65% of China’s shale gas is deeper than 3500 m, while the current technology and equipment of exploration and development are not adapted to exploration and development schemes that target shale gas in deep horizons. Third, the urgent demand of China’s natural gas market (estimated to be 600 bcm by 2030) and the high degree of external dependence (45.3% in 2018) provide a reasonable situation for the development of shale gas. Fourth, the development of supporting industries is relatively mature, and major related enterprises have clear strategic goals and obvious market competitive advantages. Fifth, the government’s incentives for the shale gas industry are insufficient, especially in terms of the intensity of financial subsidies and tax relief and the subsidy cycle. Sixth, corresponding strategies need to be implemented to strengthen all the factors in the diamond model and seize the current development chances to gain a positive interaction among them. After effective development, shale gas could become a crucial hub for balancing future economic growth and eco-environmental protection in China. Our study provides guidance for the government, policy makers, investors, and other stakeholders to better understand China’s shale gas industry and formulate corresponding development strategies.

E&P Notes (February 2021)

E&P Notes (February 2021)

Application and Discussion of Reserve-production Balance Coefficient in Oilfield

The reserve-production balance coefficient is the ratio of the annual increase in recoverable reserves to the annual oil production, also known as production reserve replacement ratio. What is the relationship between the index and the stable production of oilfield? How to use the index to predict the stable production ability of oilfield? When the annual increase in recoverable reserves is greater than the annual oil production, it can only mean that the resource base is further strengthened, but whether the annual oil production in the following year can be kept stable or increased, it also depends on the ability of new recoverable reserves to be converted into annual oil production and the magnitude of the decline rate of the previous year’s annual oil production. Based on the analysis of the critical value of stable production of the reserve-production Balance Coefficient, this paper discusses how to apply the reserve-production Balance Coefficient in oilfield development, and when the reserve-production Balance Coefficient reaches what critical value, the annual oil production of an oil field can be stabilized or increased in the next year.

Conditional Simulation for Mineral Resource Classification and Mining Dilution Assessment from the Early 1990s to Now

Andre Journel joined Stanford University in 1978, and his program grew quickly to include a dozen students from the USA, Canada, Europe, and South Africa. He was instrumental in organizing the Second International Geostatistical Conference (Tahoe ’83), during which 13 papers were presented that can be linked to his group. Out of these 13 papers, 9 were mining-related, with 7 on recoverable reserves, 2 on uncertainty, 2 on conditional simulation, and 3 on nonparametric geostatistics. A significant research effort at the time was therefore directed at change of support, global and local recoveries, and uncertainty, but future trends could also be identified, such as nonparametric geostatistics and conditional simulation. This paper is a practical review of conditional simulation as a tool to improve mineral resource estimation in the areas of uncertainty, classification, and mining selectivity or dilution, based on the authors’ experience. Some practical considerations for conditional simulation are briefly discussed. Four case studies from the early 1990s to the late 2010s are presented to illustrate some solutions and challenges encountered when dealing with real-world commercial projects.

Progress on the different methods of reserves calculation in the whole life cycle of gas reservoir development

Reserves evaluation is crucial in the whole life cycle of a gas reservoir. It is significant to figure out the various methods of reserves calculation in a systematic manner to understand and develop gas reservoirs. In the early evaluation stage, the proved reserves, which form the basis of the conceptual design and development plan for gas field development, can be determined using the volumetric method or the reservoir volume method, depending on the reservoir type. Producing reserves should be determined during the development plan's execution to guide well location. With large-scale development, the dynamic reserves and recoverable reserves of wells or reservoirs are calculated using the material balance and modern decline method to guide the optimization of technical policies such as well pattern, well spacing and production practices. In the middle and late stages of development, gas reservoir fine description and numerical simulation are used to determine the remaining reserves and lead the tapping potential. On the whole, the three factors, the spatial structure of the reservoir, the occurrence state of the fluid, and the boundary of gas reservoir, are important bases for optimizing the methods of calculating different reserves. Likewise, they are the key parameters for continuous understanding of gas reservoir during its entire life cycle development.

Estimation of net oil and gas reserves and sensitivity analysis of influencing factors for net present value under royalty & tax contracts – a case study on X project, Kazakhstan

The Royalty & Tax Contract is one of the most common cooperation modes in the international petroleum industry. Under this mode, contractors take the share of net oil and gas reserves in kind, and pay royalties, income taxes and other taxes/fees to the landowner. The net reserves owned by a contractor refer to the remaining economical recoverable reserves that the contractor can obtain during the remaining contract period, and represent the contractor’s actual revenue. Taking the XX project in Kazakhstan as an example, this paper presented the method for estimating net oil and gas reserves under the Royalty & Tax Contract, discussed how the production, decline rate, development plan, oil prices, costs and taxes affect net reserves from the technical, economic, commercial and engineering perspective, and made sensitivity analysis of the most critical influence factors like oil production, oil prices, operation expenditure and investment. Finally, some development optimization and evaluation strategies were proposed to maximize the contractors’ economic benefits.

Improving the efficiency of terrigenous oil-saturated reservoir development by the system of oriented selective slotted channels

A comparative assessment of variation in the flow rate of oil production wells was performed taking into account increasing of perforated area of the productive part of the rocks, as well as recover of reservoir rocks permeability due to their unloading by creating slotted channels with the method of oriented slotted hydro-sandblast perforation. Different orientation directions and slotting intervals were analyzed, taking into account water encroachment of individual interlayers and azimuth direction of the majority of remaining reserves in separate blocks of the examined formation.
 In order to estimate development efficiency of terrigenous oil-saturated porous-type reservoirs by means of oriented slotted hydro-sandblast perforation, calculations were performed on a full-scale geological and hydrodynamic model of an oil field in the Perm Region. The object of modeling was a Visean terrigenous productive formation. 
 The modeling of implementing oriented slotted hydro-sandblast perforation was carried out on a 3D filtration model for fourteen marginal wells, located in the zone with excessive density of remaining recoverable reserves and heterogeneous reserve recovery along the section. An optimal layout of slotted channels along the depth of the productive part of the well section was developed. Selective formation of 24 slotted channels was carried out considering the intervals of increased oil saturation. Comparative analysis of estimated flow rate of the wells was performed for cumulative perforation of the examined productive formation and the developed method of slotted perforation. As a result of modeling, an increase in the oil average flow rate of 2.25 t/day was obtained. With oriented slotted hydro-sandblast perforation, incremental cumulative production for two years of prediction calculations per one well reached 0.5 thousand t.