Predicting permeability and gas production of hydraulically fractured tight sands from microseismic data

Geophysics ◽  
2010 ◽  
Vol 75 (1) ◽  
pp. B1-B10 ◽  
Author(s):  
Vladimir Grechka ◽  
Prajnajyoti Mazumdar ◽  
Serge A. Shapiro

The main objective of hydraulic well stimulation is creating fractures in a tight rock that enhance its natural permeability and make hydrocarbon production economic. Because the geometry of fractures and the permeability of treated formation influence the subsequent production, their assessment is important for the development of tight-gas fields. The fracture shapes and orientations are inferred conventionally from microseismic data acquired in the process of well stimulation, but the same data also can be used to estimate the formation permeability. We have compared two techniques for permeability estimation that utilize different aspects of information contained in the observed microseismicity. We applied those techniques to data recorded in the course of the hydraulic fracturing of four wells drilled in the Pinedale Field, Wyoming, U.S.A. Then we used the obtained permeabilities to predict the gas rates from 20 treatment stages at which the number of identified microseismic events was sufficient to perform our analysis. The predictions of both techniques correlate with production and allow us to establish the characteristics of rocks and hydraulic fractures that make good producers at Pinedale.

2016 ◽  
Vol 19 (01) ◽  
pp. 024-040 ◽  
Author(s):  
Liliana Zambrano ◽  
Per K. Pedersen ◽  
Roberto Aguilera

Summary A comparison of rock properties integrated with production performance and hydraulic-fracturing flowback (FB) of the uppermost lithostratigraphic “Monteith A” and the lowermost portion “Monteith C” of the Monteith Formation in the Western Canada Sedimentary Basin (WCSB) in Alberta is carried out with the use of existing producing gas wells. The analyses are targeted to understand the major geologic controls that differentiate the two tight gas sandstone reservoirs. This study consists of basic analytical tools available for geological characterization of tight gas reservoirs that is based on the identification and comparison of different rock types such as depositional, petrographic, and hydraulic for each lithostratigraphic unit of the Monteith Formation. As these low-matrix-permeability sandstone reservoirs were subjected to intense post-depositional diagenesis, a comparison of the various rock types allows the generation of more-accurate reservoir description, and a better understanding of the key geologic characteristics that control gas-production potential and possible impact on hydraulic-fracturing FB. Well performance and FB were the focus of many previous simulation and geochemical studies. In contrast, we find that an adequate understanding of the rocks hosting hydraulic fractures is a necessary complement to those studies for estimating FB times. This understanding was lacking in some previous studies. As a result, a new method is proposed on the basis of a crossplot of cumulative gas production vs. square root of time for estimating FB time. It is concluded that the “Monteith A” unit has better rock quality than the “Monteith C” unit because of less-heterogeneous reservoir geometry, less-complex mineralogical composition, and larger pore-throat apertures.


Author(s):  
Amin Taghavinejad ◽  
◽  
Sepideh Shafeie ◽  
Armin Shirbazo ◽  
◽  
...  

Wastewater injection into oil and gas fields is implemented for various purposes via injection wells. Disposing of wastewater, which is mostly waste saltwater produced with hydrocarbons in oil and gas fields, into underground petroleum reservoirs are usually tied with environmental purposes. Injection of wastewater into geologic strata may encompass different applications: hazardous or non-hazardous wastewater disposal, enhanced recovery from petroleum reservoirs or merely wastewater storage. Aside from the purpose of wastewater injection, modeling of wastewater flow in porous media of underground rock strata can be challenging in different petroleum reservoirs and wells. In this study, a tight gas reservoir (TGR)—as a large-scale sustainable material to store wastewater—is considered to be studied for water disposal via a multistage fractured horizontal well (MSFHW) by numerical simulation. Host rock layer is considered to be initially saturated with low-pressure methane gas and water injection has to be performed through the hydraulic fractures of the MSFHW into the rock pore volume. Injection is performed under constant bottomhole flowing pressure and several sensitivity analyses are investigated to outline important rock characteristics in TGRs affecting performance of wastewater injection into them.


2019 ◽  
Vol 11 (10) ◽  
pp. 2838 ◽  
Author(s):  
Amjed M. Hassan ◽  
Mohamed A. Mahmoud ◽  
Abdulaziz A. Al-Majed ◽  
Dhafer Al-Shehri ◽  
Ayman R. Al-Nakhli ◽  
...  

Unconventional reservoirs have shown tremendous potential for energy supply for long-term applications. However, great challenges are associated with hydrocarbon production from these reservoirs. Recently, injection of thermochemical fluids has been introduced as a new environmentally friendly and cost-effective chemical for improving hydrocarbon production. This research aims to improve gas production from gas condensate reservoirs using environmentally friendly chemicals. Further, the impact of thermochemical treatment on changing the pore size distribution is studied. Several experiments were conducted, including chemical injection, routine core analysis, and nuclear magnetic resonance (NMR) measurements. The impact of thermochemical treatment in sustaining gas production from a tight gas reservoir was quantified. This study demonstrates that thermochemical treatment can create different types of fractures (single or multistaged fractures) based on the injection method. Thermochemical treatment can increase absolute permeability up to 500%, reduce capillary pressure by 57%, remove the accumulated liquids, and improve gas relative permeability by a factor of 1.2. The findings of this study can help to design a better thermochemical treatment for improving gas recovery. This study showed that thermochemical treatment is an effective method for sustaining gas production from tight gas reservoirs.


SPE Journal ◽  
2016 ◽  
Vol 22 (03) ◽  
pp. 924-939 ◽  
Author(s):  
Youwei He ◽  
Shiqing Cheng ◽  
Shuang Li ◽  
Yao Huang ◽  
Jiazheng Qin ◽  
...  

Summary The increasing activities in tight reservoir exploitation through fractured wells have attracted interests of pressure-transient analysis (PTA) for well-performance evaluation. The production rates of different fractures were assumed to be equal in previous models. However, different fractures have unequal contributions to the total-gas-production rate because of the differences of fracture scale (e.g., half-length, height), heterogeneity of gas saturation, formation damage, and fracture closure. This paper considers the effect of unequal gas-production rate of each fracture (UGPREF) on pressure-transient behaviors, and develops a semianalytical methodology to diagnose the specific locations of underperforming fractures through PTA by use of bottomhole-pressure (BHP) data. First, new semianalytical solutions of a multifractured horizontal well (MFHW) in a tight gas reservoir are derived on the basis of the Green function (Gringarten and Ramey 1973) and Newman product method (Newman 1936). Second, the model is validated by comparison with the numerical model in KAPPA Ecrin (Saphir) software (Essca 2011). Third, type curves are developed, and sensitivity analysis is further investigated. Results show that there exist clear distinctions among these type curves between equal gas-production rate of each fracture (EGPREF) and UGPREF. The early radial flow is distinguishable and behaves as a horizontal line with the value of 0.5/N* (N* = N for EGPREF, N*≠N for UGPREF) in the pseudopressure-derivative curves when the interferences between fractures do not overlap this period. If the early-radial flow was mistakenly regarded as pseudoradial flow, the interpreted permeability would be N* times smaller than the accurate result. Furthermore, the methodology is applied to a field case of the Daniudi tight gas reservoir in the Ordos Basin, which illustrates its physical consistency and practicability to diagnose the specific locations of underperforming hydraulic fractures through pressure-history matching. It also provides feasible references for reservoir engineers in well-performance evaluation and field strategy (e.g., refracturing, acidizing, or other stimulation treatments) to enhance hydrocarbon production.


2018 ◽  
Vol 5 ◽  
pp. 11-26
Author(s):  
Oleksandr Filipchuk ◽  
Victor Marushchenko ◽  
Mikhailo Bratakh ◽  
Myroslav Savchuk ◽  
Safaa Tarwat

To date, Ukraine's mature gas fields, which are being developed in the gas regime, are at the final stage of development, which is characterized by a significant depletion of reservoir energy. The final stage of development requires solving complex problems related to watering wells, destruction of the reservoir, removal of formation water and mechanical impurities, increasing back pressure in the system, as well as the moral and physical wear and tear of industrial equipment. In the conditions of falling gas production, a significant part of the operating well stock is unstable, in the mode of unauthorized stops due to the accumulation of liquid at the bottom and insufficient gas velocities for removal to the surface, and also the accumulation of the liquid phase in the lowered places of the gas gathering system. Within the framework of the conducted studies, the gas dynamic models of the operation of the gas collection system of 3 oil/gas-condensate fields (OGCF) are created. A single model of the gas production system "reservoir - well - gas gathering system - inter-field gas pipeline - main facilities" is built. The current efficiency of the gas production, collection and transportation system is assessed. On the basis of model calculations, the current production capabilities of the wells are defined, as well as the "narrow" places of the system. It is established that the introduction of modern technologies for the operation of watered wells without optimizing the operation of the entire gas production system is irrational, since the liquid that is carried out from the wellbore will accumulate in the plumes and increase the back pressure level in the ground part. In conditions of increasing gas sampling, liquid flowlines can be taken out of the loops and deactivated the separation equipment. The feasibility of introducing methods for optimizing the operation modes of the gas production - gathering and transportation system is estimated, which allows choosing the optimal method for increasing the efficiency and reliability of its operation. For the first time in the Ukrainian gas industry, an integrated model of the field is created as a single chain of extraction, collection, preparation and transportation of natural gas, which can be adapted for the development and arrangement of both new and mature deposits. The main advantage of the application for the hydrocarbon production sector is the simulation of the processes, which makes it possible to evaluate the operating mode of the well in the safe zone while reducing the working pressure and introducing various intensification methods, and also to estimate the increase in hydrocarbon production. For the equipment of the ground infrastructure – "midstream" – the main advantage is a reduction in the time required to perform design calculations for gas pipelines, trains and pipelines for transporting multiphase media using public models. The creation and use of integrated models of gas fields gives an understanding of the integral picture of available resources and ensures an increase in the efficiency of field development management. The results of the calculation are clearly correlated with the actual data, which makes it possible to use the models constructed to obtain numerical results.


2011 ◽  
Vol 51 (1) ◽  
pp. 519
Author(s):  
Jakov Ostojic ◽  
Reza Rezaee ◽  
Hassan Bahrami

The increasing global demand for energy along with the reduction in conventional gas reserves has lead to the increasing demand and exploration of unconventional gas sources. Hydraulically-fractured tight gas reservoirs are one of the most common unconventional sources being produced today and look to be a regular source of gas in the future. Hydraulic fracture orientation and spacing are important factors in effective field drainage and gas recovery. This paper presents a 3D single well hydraulically fractured tight gas model created using commercial simulation software, which will be used to simulate gas production and synthetically generate welltest data. The hydraulic fractures will be simulated with varying sizes and different numbers of fractures intersecting the wellbore. The focus of the simulation runs will be on the effect of hydraulic fracture size and spacing on well productivity performance. The results obtained from the welltest simulations will be plotted and used to understand the impact on reservoir response under the different hydraulic fracturing scenarios. The outputs of the models can also be used to relate welltest response to the efficiency of hydraulic fractures and, therefore, productivity performance.


2021 ◽  
Author(s):  
Adnan Bin Asif ◽  
Mustafa Alaliwat ◽  
Jon Hansen ◽  
Mohamed Sheshtawy

Abstract The main objective of the acoustic logging in 15K openhole multistage fracturing completions (OH MSFs) is to identify the fracture initiation points behind pipe and contributing fractures to gas production. The technique will also help to understand the integrity of the OH packers. A well was identified to be a candidate for assessment through such technique. The selected well was one of the early 15K OH MSF completions in the region that was successfully implemented with the goal of hydrocarbon production at sustained commercial rates from a gas formation. The candidate well was drilled horizontally to achieve maximum contact in a tight gas sandstone formation. Similar wells in the region have seen many challenges of formation breakdown due to high formation stresses. The objective of this work is to use the acoustic data to better characterize fracture properties. The deployment of acoustic log technology can provide information of fractures initiation, contribution for the production and the reliability of the isolation packers between the stages. The candidate well was completed with five stages open-hole fracturing completion. As the well is in an open hole environment, a typical PLT survey provides the contribution of individual port in the cumulative production but provides limited or no information of contributing fractures behind the pipe. The technique of acoustic logging helped to determine the fracture initiation points in different stages. If fractures can be characterized more accurately, then flow paths and flow behaviors in the reservoir can be better delineated. The use of acoustic logging has helped to better understand the factors influencing fracture initiation in tight gas sandstone reservoirs; resulting in a better understanding of fractures density and decisions on future openhole length, number of fracturing stages, packers and frac ports placement.


2021 ◽  
pp. 1-18
Author(s):  
Yunzhao Zhang ◽  
Lianbo Zeng ◽  
Wenya Lyu ◽  
Dongsheng Sun ◽  
Shuangquan Chen ◽  
...  

Abstract The Upper Triassic Xujiahe Formation is a typical tight gas reservoir in which natural fractures determine the migration, accumulation and production capacity of tight gas. In this study, we focused on the influences of natural fractures on the tight gas migration and production. We clarified characteristics and attributes (i.e. dips, apertures, filling degree and cross-cutting relationships) of the fractures based on image logging interpretations and core descriptions. Previous studies of electron spin resonance, carbon and oxygen isotopes, homogenization temperature of fluid inclusions analysis and basin simulation were considered. This study also analysed the fracture sequences, source of fracture fillings, diagenetic sequences and tight gas enrichment stages. We obtained insight into the relationship between fracture evolution and hydrocarbon charging, particularly the effect of the apertures and intensity of natural fractures on tight gas production. We reveal that the bedding fractures are short horizontal migration channels of tight gas. The tectonic fractures with middle, high and nearly vertical angles are beneficial to tight gas vertical migration. The apertures of fractures are controlled by the direction of maximum principal stress and fracture angle. The initial gas production of the vertical wells presents a positive correlation with the fracture abundance, and the intensity and aperture of fractures are the fundamental factors that determine the tight gas production. With these findings, this study is expected to guide the future exploration and development of tight gas with similar geological backgrounds.


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