scholarly journals Drill core from seismically active sandstone gas reservoir yields clues to internal deformation mechanisms

Geology ◽  
2020 ◽  
Author(s):  
Berend A. Verberne ◽  
Suzanne J.T. Hangx ◽  
Ronald P.J. Pijnenburg ◽  
Maartje F. Hamers ◽  
Martyn R. Drury ◽  
...  
Keyword(s):  
Microstructural Analysis ◽  
Gas Production ◽  
Drill Core ◽  
Gas Reservoir ◽  
Gas Field ◽  
Reservoir Compaction ◽  
Key Factor ◽  
Forecasting System ◽  
Internal Deformation ◽  
Dauphiné Twinning

Europe’s largest gas field, the Groningen field (the Netherlands), is widely known for induced subsidence and seismicity caused by gas pressure depletion and associated compaction of the sandstone reservoir. Whether compaction is elastic or partly inelastic, as implied by recent experiments, is a key factor in forecasting system behavior and seismic hazard. We sought evidence for inelastic deformation through comparative microstructural analysis of unique drill core recovered from the seismogenic center of the field in 2015, 50 yr after gas production started, versus core recovered before production (1965). Quartz grain fracturing, crack healing, and stress-induced Dauphiné twinning are equally developed in the 2015 and 1965 cores, with the only measurable effect of gas production being enhanced microcracking of sparse K-feldspar grains in the 2015 core. Interpreting these grains as strain markers, we suggest that reservoir compaction involves elastic strain plus inelastic compression of weak clay films within grain contacts.

A Comprehensive Approach for Fracability Evaluation in Naturally Fractured Sandstone Reservoirs

2018 ◽  
Author(s):  
Zhaozhong Yang ◽  
Rui He ◽  
Xiaogang Li ◽  
Zhanling Li ◽  
Ziyuan Liu
Keyword(s):  
Large Scale ◽  
Evaluation Model ◽  
Gas Production ◽  
Natural Fracture ◽  
Tight Sandstone ◽  
Gas Reservoir ◽  
Related Factors ◽  
Gas Field ◽  
Tight Gas Reservoir ◽  
Naturally Fractured

The tight sandstone gas reservoir in southern Songliao Basin is naturally fractured and is characterized by its low porosity and permeability. Large-scale hydraulic fracturing is the most effective way to develop this tight gas reservoir. Quantitative evaluation of fracability is essential for optimizing a fracturing reservoir. In this study, as many as ten fracability-related factors, particularly mechanical brittleness, mineral brittleness, cohesion, internal friction angle, unconfined compressive strength (UCS), natural fracture, Model-I toughness, Model-II toughness, horizontal stress difference, and fracture barrier were obtained from a series of petrophysical and geomechanical experiments are analyzed. Taking these influencing factors into consideration, a modified comprehensive evaluation model is proposed based on the analytic hierarchy process (AHP). Both a transfer matrix and a fuzzy matrix were introduced into this model. The fracability evaluation of four reservoir intervals in Jinshan gas field was analyzed. Field fracturing tests were conducted to verify the efficiency and accuracy of the proposed evaluation model. Results showed that gas production is higher and more stable in the reservoir interval with better fracability. The field test data coincides with the results of the proposed evaluation model.

scholarly journals Short-Term Model-Based Production Optimization for a Gas Field in North Africa

2018 ◽  
Vol 10 (2) ◽  
pp. 65
Author(s):  
Arnaud Hoffmann
Keyword(s):  
Piecewise Linear ◽  
Treatment Plant ◽  
Gas Production ◽  
Production Optimization ◽  
Mixed Integer ◽  
Short Term ◽  
Gas Reservoir ◽  
Gas Field ◽  
Gas Treatment ◽  
Model Based

 This paper presents a model-based optimization solution suitable for short-term production optimization of large gas fields with wells producing into a common surface network into a shared gas treatment plant. The proposed methodology is applied to a field consisting of one dry gas reservoir with a CO2 content of 7.3% and one wet gas reservoir with a CO2 content of 2.8% and initial CGR of 15 stb/MMscf. 23 wells are producing, and all gas production is processed in a common gas treatment plant where condensates and CO2 are extracted from the reservoir gas. The final sales gas must honor compositional constraints (CO2 content and heating value). The proposed solution consists of a bi-level optimization algorithm. A Mixed Integer Linear Programming (MILP) formulation of the optimization problem is solved, assuming some key parameters in the gas plant to be constant. Hydraulic performances of the system, approximated using SOS2 piecewise linear models, and condensates and CO2 extraction, captured using simplified models, are included in the MILP. After solving the MILP, the values of the key parameters are calculated using a full simulation model of the gas plant and the new values are substituted in the MILP input data. This iterative procedure continues until convergence is achieved. Results show that the proposed methodology can find the optimum choke openings for all wells to maximize the total gas rate while honoring numerous surface constraints. The solution runs in 30 sec. and an average of 3-4 iterations is needed to achieve convergence. It is therefore a suitable solution for short-term production optimization and daily operations.

scholarly journals Supplemental Material: Drill core from seismically active sandstone gas reservoir yields clues to internal deformation mechanisms

2020 ◽  
Author(s):  
Berend Verberne ◽  
Suzanne Hangx ◽  
et al.
Keyword(s):  
Deformation Mechanisms ◽  
Drill Core ◽  
Gas Reservoir ◽  
Internal Deformation

Detailed description of the materials and methods employed in this study, Figures S1–S8, and Tables S1–S4.<br>

scholarly journals Incorporating dwelling mounds into induced seismic risk analysis for the Groningen gas field in the Netherlands

2021 ◽  
Author(s):  
Pauline P. Kruiver ◽  
Manos Pefkos ◽  
Erik Meijles ◽  
Gerard Aalbersberg ◽  
Xander Campman ◽  
...  
Keyword(s):  
The Netherlands ◽  
Seismic Risk ◽  
Site Response ◽  
Gas Production ◽  
Fragility Functions ◽  
Gas Field ◽  
Amplification Factors ◽  
Reservoir Compaction ◽  
Groningen Gas Field ◽  
The Impact

AbstractIn order to inform decision-making regarding measures to mitigate the impact of induced seismicity in the Groningen gas field in the Netherlands, a comprehensive seismic risk model has been developed. Starting with gas production scenarios and the consequent reservoir compaction, the model generates synthetic earthquake catalogues which are deployed in Monte Carlo analyses, predicting ground motions at a buried reference rock horizon that are combined with nonlinear amplification factors to estimate response spectral accelerations at the surface. These motions are combined with fragility functions defined for the exposed buildings throughout the region to estimate damage levels, which in turn are transformed to risk in terms of injury through consequence functions. Several older and potentially vulnerable buildings are located on dwelling mounds that were constructed from soils and organic material as a flood defence. These anthropogenic structures are not included in the soil profile models used to develop the amplification factors and hence their influence has not been included in the risk analyses to date. To address this gap in the model, concerted studies have been identified to characterize the dwelling mounds. These include new shear-wave velocity measurements that have enabled dynamic site response analyses to determine the modification of ground shaking due to the presence of the mound. A scheme has then been developed to incorporate the dwelling mounds into the risk calculations, which included an assessment of whether the soil-structure interaction effects for buildings founded on the mounds required modification of the seismic fragility functions.

scholarly journals MODELING OF DISPLACEMENT PROCESSES IN HETEROGENEOUS ANISOTROPIC GAS RESERVOIRS

2021 ◽  
pp. 94-99
Author(s):  
M. Lubkov ◽  
O. Zaharchuk
Keyword(s):  
Computer Modeling ◽  
Gas Production ◽  
Practical Case ◽  
Reservoir Properties ◽  
Gas Reservoir ◽  
Injection Wells ◽  
Gas Field ◽  
Heterogeneous Distribution ◽  
Anisotropic Reservoirs ◽  
Gas Bearing

Nowadays there are important problems of increasing efficiency of development and exploitation of gas deposits. There are problems associated with the growth of gas production in heterogeneous anisotropic reservoirs, increasing gas recovery, achieving economic efficiency and so on. In this situation, there are popular methods of computer modeling of gas productive reservoirs, because they allow getting information of the structure and characteristics of the gas reservoir, the distribution parameters of permeability and other important factors in it. They also allow evaluating and calculating uncertainty arising from the lack of information about the gas reservoir properties outside the well. Currently there are many methods of computer modeling, allowing solving various practical problems. From another hand there are some problems related to the accuracy and adequacy of simulation of heterogeneous anisotropic permeable collector systems in real conditions of gas deposits exploitation. On the base of combined finite-element-difference method for solving the nonstationary anisotropic piezoconductivity Lebenson problem, with calculating of heterogeneous distribution of permeable characteristics of the gas reservoir, we carried out modeling of filtration processes between production and injection wells. The results of computer modeling show that intensity of the filtration process between production and injection wells depends essentially on their location both in a shifting-isotropic and anisotropic gas reservoir. Therefore, for the effective using of poorly permeable shifting-isotropic gas-bearing reservoirs, it is necessary to place production and injection wells along the main anisotropy axes of the gas-bearing layers. At the placing production and injection well systems in low-permeable anisotropic reservoirs of a gas field, the most effective exchange between them will take place when the direction of increased permeability of the reservoirs coincides with the direction of the location of the wells. Obviously, the best conditions for gas production processes in any practical case can be achieved due to optimal selection of all anisotropic filtration parameters of the gas reservoir. One can use obtained results for practical geophysical works with a purpose optimizing of gas production activity in low-permeable heterogeneous anisotropic reservoirs. Presented method for more detailed investigation of low-permeable heterogeneous anisotropic gas-bearing deposits can be used.

scholarly journals Supplemental Material: Drill core from seismically active sandstone gas reservoir yields clues to internal deformation mechanisms

2020 ◽  
Author(s):  
Berend Verberne ◽  
Suzanne Hangx ◽  
et al.
Keyword(s):  
Deformation Mechanisms ◽  
Drill Core ◽  
Gas Reservoir ◽  
Internal Deformation

Detailed description of the materials and methods employed in this study, Figures S1–S8, and Tables S1–S4.<br>

scholarly journals New approaches in experimental research on rock and fault behaviour in the Groningen gas field

2017 ◽  
Vol 96 (5) ◽  
pp. s55-s69 ◽  
Author(s):  
Christopher J. Spiers ◽  
Suzanne J.T. Hangx ◽  
André R. Niemeijer
Keyword(s):  
Research Programme ◽  
Gas Production ◽  
Reservoir Rock ◽  
Fault Mechanics ◽  
Gas Field ◽  
Reservoir Compaction ◽  
First Results ◽  
Experimental Rock ◽  
Earthquake Generation ◽  
Groningen Gas Field

AbstractThis paper describes a research programme recently initiated at Utrecht University that aims to contribute new, fundamental physical understanding and quantitative descriptions of rock and fault behaviour needed to advance understanding of reservoir compaction and fault behaviour in the context of induced seismicity and subsidence in the Groningen gas field. The NAM-funded programme involves experimental rock and fault mechanics work, microscale observational studies to determine the processes that control reservoir rock deformation and fault slip, modelling and experimental work aimed at establishing upscaling rules between laboratory and field scales, and geomechanical modelling of fault rupture and earthquake generation at the reservoir scale. Here, we focus on describing the programme and its intended contribution to understanding the response of the Groningen field to gas production. The key knowledge gaps that drive the programme are discussed and the approaches employed to address them are highlighted. Some of the first results emerging from the work in progress are also reported briefly and are providing important new insights.

A particle method strategy to estimate subsidence induced by a high-dimensional disc-strain model for reservoir compaction.

2020 ◽  
Author(s):  
Samantha Kim ◽  
Femke Vossepoel ◽  
Ramon F. Hanssen ◽  
Marius Wouters ◽  
Rob Govers ◽  
...  
Keyword(s):  
Surface Deformation ◽  
Particle Method ◽  
Ensemble Size ◽  
Gas Reservoir ◽  
Gas Field ◽  
Reservoir Compaction ◽  
Single Nucleus ◽  
Small Ensemble ◽  
Importance Resampling ◽  
Strain Model

&lt;p&gt;This work is part of the &quot;Subsidence&quot; DeepNL project which aims to identify subsurface drivers of subsidence above the Groningen (the Netherlands) gas field and to forecast future subsidence. The hydrocarbon extraction in Groningen induces a pressure reduction in the gas reservoir which triggers compaction and land subsidence. This deep-subsurface process is modeled by a disc-shaped reservoir model, which is a superposition of individual nuclei of strain based on the Geertsma's approach. We estimate the surface deformation and the strength of the disc strain using a particle method. We apply the method to one single nucleus of strain at 3 km depth and extend to a disc-shape geometry. Synthetic experiments with a single nucleus of strain and with discs of varying sizes, 2.2 km to 13.3 km diameter, at 3 km depth are performed to assess the performance of the method for an increasing degree of complexity. Sequential Importance Resampling prevents the sample degeneracy when the number of nuclei increases. Adding a jitter noise in the resampling step avoids an impoverishment of the ensemble values. The results indicate that the method estimates the surface deformation and the strength for a large number of sources and for a relatively small effective ensemble size. In further investigations, localization can provide an additional means to deal with increasing dimensions and a relatively small ensemble size.&lt;/p&gt;

scholarly journals Probabilistic earthquake locations of induced seismicity in the Groningen region, the Netherlands

2020 ◽  
Vol 222 (1) ◽  
pp. 507-516 ◽  
Author(s):  
Jonathan D Smith ◽  
Robert S White ◽  
Jean-Philippe Avouac ◽  
Stephen Bourne
Keyword(s):  
The Netherlands ◽  
Depth Distribution ◽  
Velocity Model ◽  
Gas Production ◽  
Gas Field ◽  
Arrival Times ◽  
S Waves ◽  
Reservoir Compaction ◽  
Earthquake Locations ◽  
Projection Techniques

SUMMARY The Groningen gas reservoir, situated in the northeast of the Netherlands, is western Europe’s largest producing gas field and has been in production since 1963. The gas production has induced both subsidence and seismicity. Seismicity is detected and located using the Koninklijk Nederlands Meteorologisch Instituut shallow-borehole array for the period 2015–2017, incorporating the back projection techniques of QuakeMigrate and the nonlinear location procedure to constrain earthquake locations and depths. The uncertainties on the estimated depths are estimated taking into account velocity model, changes in station array geometry and uncertainties in the measurement of arrival times of the P and S waves. We show that the depth distribution of seismicity is consistent with nucleation within the reservoir (28 per cent) or in the overburden (60 per cent) within ∼500 m from the top of the reservoir. Earthquakes with hypocentres in the overburden likely originate from overlying Zechstein anhydrite caprock. Based on their depth distribution, it seems like the earthquakes are primarily driven by the elastic strain in the reservoir and overburden, induced by the reservoir compaction. We estimate the probability of earthquakes nucleating beneath the reservoir in the underlying Carboniferous limestone and basement, to be no more than 12 per cent.

scholarly journals Integrated Reservoir Study to Optimize Gas Production of Water Drive Gas Reservoir Case Study: Lower Menggala Gas Field

INSIST ◽  
2018 ◽  
Vol 3 (2) ◽  
pp. 154
Author(s):  
Panca Suci Widiantoro ◽  
Astra Agus Pramana ◽  
Putu Suarsana ◽  
Anis N Utami
Keyword(s):  
Material Balance ◽  
Gas Production ◽  
Production Optimization ◽  
Balance Method ◽  
Water Production ◽  
Gas Reservoir ◽  
Gas Field ◽  
Production Analysis ◽  
Conventional Material ◽  
Material Balance Method

Production optimization in mature field water drive gas reservoir is not easy especially when water already breakthrough in producing wells. An integrated reservoir study is needed to get reliable strategy to optimize production of water drive gas reservoir.   This research presents the integrated reservoir study of Lower Menggala (LM) Gas Field which is located Central Sumatera Basin, Riau Province. LM had been produced since 1997, current RF are 55%, which is quite high for water drive gas reservoir. The current gas rate production is about 1.97 MMscfd with high water production around 4250 BWPD, consequently some of wells suffered liquid loading problem   This research comprises of well performance analysis, estimate OGIP, aquifer strength of the reservoir by using conventional material balance method and modern production analysis method then conduct dynamic reservoir simulation to identify the best strategy to optimize gas production. Economic analysis also be performed to guide in making decision which scenario will be selected. DST analysis on DC-01 well defined reservoir parameter, boundary and deliverability which are P*= 2520 psia, k= 229 mD, Total skin= 8, detected sealing fault with distance 175 m, and AOF 45 MMscfd. Conventional material balance method gave OGIP 22.7 BScf, aquifer strength 34 B/D/Psi, whereas modern production analysis estimated OGIP 22.35 BScf, aquifer strength 34 B/D/psi. Those two method shows  good consistency with OGIP  volumetric calculation with discrepancy OGIP value +/- 1%. Six (6) scenario of production optimization has been analyzed, the result shows that work over in two wells and drilling of  1 infill well (case 6) achieve gas recovery factor up to 75.2%, minimal water production and attractive economic result

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