Acid Fracturing Tight Gas Carbonates Reservoirs Using CO2 to Assist Stimulation Fluids: An Alternative to Less Water Consumption while Maintaining Productivity

2015 ◽  
Author(s):  
Mauricio Sanchez ◽  
Justin Tate Abel ◽  
Muhammad Idris ◽  
Eduardo Soriano ◽  
Alfredo Lopez ◽  
...  
Keyword(s):  
Water Consumption ◽  
Physical And Mechanical Properties ◽  
Point Of View ◽  
Tight Gas ◽  
Gas Reservoirs ◽  
Tight Sandstone ◽  
Acid Fracturing ◽  
Fracturing Fluids ◽  
Tight Carbonate ◽  
Carbon Dioxide Co2

Abstract Conventional hydraulic fracture stimulation techniques have been widely used to enhance production from tight gas reservoirs. Since the initial use of this method to increase production rates, the industry has witnessed continued advancement in terms of fracturing theory, fluids, and techniques. The use of carbon dioxide (CO2) since the early 1960s has continued to be a significant part of these advances. CO2 has been used for many years as an energy source to aid fluid recovery of well stimulation fluids. This technology predominantly has been used to stimulate tight sandstone reservoirs. There are very limited applications for low permeable tight carbonate reservoirs because of complexities associated with the physical and mechanical properties of carbonate rocks and its interaction with fracturing fluid. Nevertheless, the advantages of using assisted CO2 stimulation fluids as the elimination of potential formation damage normally associated with fracturing fluids and very rapid cleanup are still present. This paper outlines one of the first acid fracturing jobs assisted with CO2 conducted on a tight gas well reservoir in Saudi Arabia. It describes in a simple manner the screening methodology and key parameters considered during selection of a well candidate and the design process, which was based on petrophysical, mechanical, and chemistry properties of the formation and the respective interaction with treatment fluids. Moreover, primary operational procedures and guidelines are discussed, highlighting a safety risk assessment point of view. Implementing this technique in a more generalized manner in the field can help save considerable operational time and costs. CO2 used to energized fracturing fluids can increase the productivity of the well while using less water and less acid than conventional acid fracturing, which is of primary importance in such a harsh environment, requiring less water consumption.

scholarly journals Experimental Study on the Effective Utilization of Reserves in Tight Sandstone Gas Reservoirs and Their Applications

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Jie Zhang ◽  
Feifei Fang ◽  
Weijun Shen ◽  
Huaxun Liu ◽  
Shusheng Gao ◽  
...  
Keyword(s):  
Pressure Distribution ◽  
Moving Boundary ◽  
Production Performance ◽  
Tight Gas ◽  
Gas Reservoirs ◽  
Tight Sandstone ◽  
Effective Utilization ◽  
Tight Gas Reservoir ◽  
Water Cut ◽  
Field Production

The effective utilization of reserves in tight sandstone reservoirs is one of the major concerns in terms of the development of tight sandstone gas reservoirs. However, the characteristics of reserve utilization are not fully understood, and many uncertainties still exist in the process. For this purpose, long cores on the Su 6 block of Sulige tight sandstone gas field in China were selected, and a multipoint embedded measurement system was established to study the characteristics of effective reserve utilization. Then, the effects of the related reservoir properties and production parameters were investigated. Based on the similarity theory, the effective conversion relationship between the physical experiment and the actual field production was established. The results showed that the pressure distribution in the exploitation of tight gas reservoir is nonlinear, and water cut in the reservoir will hinder the effective utilization of reserves. The lower the reservoir permeability, the larger the negative effect of water on reservoir utilization. Lower gas production rate and higher original pressure are associated with a smoother drawdown curve, which results in larger reserve utilization. The moving boundary expands with time, and its initial propagation velocity increase and then decrease. Additionally, the water cut in the reservoir can delay the spread of moving boundary propagation. The experimental results are consistent with the actual results of the field production by the similarity criterion, which can reflect and predict the production performance in tight gas reservoirs effectively. These results can provide a better understanding of reservoir pressure distribution and effective utilization of reserves to optimize the gas recovery and development benefit in tight sandstone gas reservoirs.

scholarly journals Pre-acid system for improving the hydraulic fracturing effect in low-permeability tight gas reservoir

2021 ◽  
Vol 11 (4) ◽  
pp. 1761-1780
Author(s):  
Nianyin Li ◽  
Fei Chen ◽  
Jiajie Yu ◽  
Peihong Han ◽  
Jia Kang
Keyword(s):  
Hydraulic Fracturing ◽  
Filter Cake ◽  
Low Permeability ◽  
Tight Gas ◽  
Acid System ◽  
Fracturing Fluid ◽  
Gas Reservoirs ◽  
Tight Gas Reservoirs ◽  
Acid Fracturing ◽  
Performance Requirements

AbstractHydraulic fracturing is an important technical means to improve the development effect of low-permeability oil and gas reservoirs. However, for low pressure, low-permeability, tight, and high-clay sandstone gas reservoirs, conventional propped fracturing can cause serious damage to the reservoir and restrict the fracturing effect. The pre-acid fracturing technology combines acid treatment technology with sand-fracturing technology. A pre-acid system that meets special performance requirements is injected before fracturing. The pre-acid reduces the formation fracture pressure and removes clay damage. During acid flowback, the fracturing fluid is promoted to break the gel, dissolve the fracturing fluid residue and polymer filter cake, clean the supporting cracks, and effectively improve the fracturing effect. This study analyzes the process principle and technical advantages of the pre-acid fracturing technology based on the laboratory evaluation of the fracturing damage mechanism of low-permeability tight gas reservoirs. To meet the performance requirements of low-permeability tight gas reservoirs and pre-acid fracturing technology, a set of polyhydrogen acid system with long-lasting slow reactivity, low damage, and low corrosion was developed and used as the pre-fracturing acid. The acid system is mainly composed of the main agent SA601 and the auxiliary agent SA701. Then, on the basis of laboratory experiments, this acid system is used as the fracturing pre-acid to evaluate the fracturing improvement effect. The results show that the fracturing fluid system can better dissolve the fracturing fluid filter cake and remove the fracturing fluid damage.

scholarly journals Pore Structure Differentiation between Deltaic and Epicontinental Tight Sandstones of the Upper Paleozoic in the Eastern Linxing Area, Ordos Basin, China

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Jimei Deng ◽  
Huan Zeng ◽  
Peng Wu ◽  
Jia Du ◽  
Jixian Gao ◽  
...  
Keyword(s):  
Hot Spot ◽  
Ordos Basin ◽  
Central Area ◽  
Gas Production ◽  
Tight Gas ◽  
Gas Reservoirs ◽  
Tight Sandstone ◽  
The North ◽  
Taiyuan Formation ◽  
Diagenetic Evolution

Research on tight gas reservoirs in the eastern margin of the Ordos Basin, China, has recently become a hot spot. This paper mainly studies the reservoir characteristics of tight sandstone in the north-central area close to the provenance in eastern Linxing. Cast thin section, scanning electron microscopy, high-pressure mercury injection, and X-ray diffraction (XRD) were applied to discriminate the tight sandstone reservoir differences between the Permian Taiyuan and Shanxi formations in the study area. The results show that the deltaic tight sandstones in the Shanxi Formation are dominated by lithic quartz sandstone and lithic sandstone with an average porosity of 2.3% and permeability of 0.083 mD. The epicontinental tight sandstones in the Taiyuan Formation are mainly lithic sandstone and lithic quartz sandstone, with average porosities and permeabilities of 6.9% and 0.12 mD, respectively. The pore type is dominated by secondary dissolution pores, containing a small number of primary pores, and fractures are not developed. The capillary pressure curves of the Taiyuan Formation sandstone are mainly of low displacement pressure, high mercury saturation, and mercury withdrawal efficiency, while the Shanxi Formation sandstone is mainly of high displacement pressure, low mercury saturation, and withdrawal efficiency. The diagenetic evolution of sandstone in the Shanxi Formation is in meso-diagenesis stage A, and the Taiyuan Formation has entered meso-diagenesis stage B. The siliceous cement in the Taiyuan Formation sandstone enhanced the sandstone resistance to compaction and retained some residual intergranular pores. The pore types in the Shanxi Formation sandstone are all secondary pores, while secondary pores in the Taiyuan Formation sandstone account for approximately 90%. The results can be beneficial for tight gas production in the study area and similar basins.

scholarly journals Threshold Pore Pressure Gradients in Water-Bearing Tight Sandstone Gas Reservoirs

Energies ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 4578
Author(s):  
Yong Wang ◽  
Yunqian Long ◽  
Yeheng Sun ◽  
Shiming Zhang ◽  
Fuquan Song ◽  
...  
Keyword(s):  
Water Saturation ◽  
High Water ◽  
Linear Regression Method ◽  
Tight Gas ◽  
Gas Reservoirs ◽  
Tight Sandstone ◽  
Gas Reservoir ◽  
Gas Seepage ◽  
Tight Gas Reservoir ◽  
Core Permeability

Tight gas reservoirs commonly occur in clastic formations having a complex pore structure and a high water saturation, which results in a threshold pressure gradient (TPG) for gas seepage. The micropore characteristics of a tight sandstone gas reservoir (Tuha oilfield, Xinjiang, China) were studied, based on X-ray diffraction, scanning electron microscopy and high pressure mercury testing. The TPG of gas in cores of the tight gas reservoir was investigated under various water saturation conditions, paying special attention to core permeability and water saturation impact on the TPG. A mathematical TPG model applied a multiple linear regression method to evaluate the influence of core permeability and water saturation. The results show that the tight sandstone gas reservoir has a high content of clay minerals, and especially a large proportion of illite–smectite mixed layers. The pore diameter is distributed below 1 micron, comprising mesopores and micropores. With a decrease of reservoir permeability, the number of micropores increases sharply. Saturated water tight cores show an obvious non-linear seepage characteristic, and the TPG of gas increases with a decrease of core permeability or an increase of water saturation. The TPG model has a high prediction accuracy and shows that permeability has a greater impact on TPG at high water saturation, while water saturation has a greater impact on TPG at low permeability.

The Characteristics of Tight Gas Reservoirs Microscopic Pore Structure - To Sulige Gas Field as an Example

2015 ◽  
Vol 1092-1093 ◽  
pp. 1485-1489 ◽  
Author(s):  
Jun Sheng ◽  
Wei Sun ◽  
Ji Lei Qin ◽  
Shi Guo Liu ◽  
Ai Ju Li ◽  
...  
Keyword(s):  
Pore Structure ◽  
Physical Characteristics ◽  
Tight Gas ◽  
Gas Reservoirs ◽  
Tight Sandstone ◽  
Gas Field ◽  
Tight Gas Reservoirs ◽  
Constant Rate ◽  
Sandstone Reservoir ◽  
The Impact

The research is based on conventional microscope experiments, the characteristics of microscopic pore structure of tight sandstone reservoir were analyzed via the constant-rate mercury experiment. This paper selected samples of tight sandstone are from the Southeast area of Erdos basin Sulige gas field. The results showed that the dissolution pore and the intergranular pore were mainly reservoir pore structure types; the bundle throat and the lamellar throat were mainly types of throat in the study area. The mainly configure relations of the pore and throat in this area were big pore - fine / fine throat. Finally, according to constant-rate mercury results, analyzed the impact of pore and throats for percolation capacity respectively, came to the conclusions that the tight sandstone gas reservoirs percolation capability in study area is mainly affected by the throat, and the development degree of the throat determines the final physical characteristics of the reservoir.

scholarly journals Experimental investigation of two-phase relative permeability of gas and water for tight gas carbonate under different test conditions

2019 ◽  
Vol 74 ◽  
pp. 23 ◽  
Author(s):  
Teng Wan ◽  
Shenglai Yang ◽  
Lu Wang ◽  
Liting Sun
Keyword(s):  
Relative Permeability ◽  
Factor Model ◽  
Ct Scanning ◽  
Wettability Alteration ◽  
Tight Gas ◽  
Tight Sandstone ◽  
Two Phase ◽  
Slippage Effect ◽  
Tight Carbonate ◽  
Relative Permeability Curves

Currently, tight carbonate gas reservoir has received little attention due to few discoveries of them. In this study, gas–water two-phase relative permeability was measured under two different conditions: High Temperature High Pore Pressure (HTHPP – 80 °C, 38 MPa), as well as Ambient Condition (AC), using whole core samples of tight gas carbonate. Relative permeability curves obtained at HTHPP showed two contrary curve profiles of gas relative permeability, corresponding to the distinctive micro-pore structure acquired from CT-Scanning. Then, based on Klinkenberg theory and a newly developed slip factor model for tight sandstone, slippage effect under AC is calibrated and the overestimation of gas relative permeability prove up to 41.72%–52.34% in an assumed heterogeneity. In addition, relative permeability curves obtained at HTHPP switch to higher gas saturation compared to that under AC with the rock wettability change from water-wet to less water-wet. And the wettability alteration is believed to be caused by charge change on mineral surface.

Acid Fracturing Tight Gas Carbonates Reservoirs Using CO2 to Assist Stimulation Fluids: An Alternative to Less Water Consumption while Maintaining Productivity

2015 ◽  
Author(s):  
Mauricio Sanchez Bernal ◽  
Justin Tate ◽  
Muhammad Idris ◽  
J Eduardo Soriano ◽  
Alfredo Eduardo Lopez ◽  
...  
Keyword(s):  
Water Consumption ◽  
Tight Gas ◽  
Acid Fracturing

The Application of Decision Tree Method to the Identification of Formation Types in Tight Gas Reservoirs

2012 ◽  
Vol 170-173 ◽  
pp. 969-974
Author(s):  
Hai Ying Han ◽  
Zhi Zhang Wang ◽  
Li Chang Wang
Keyword(s):  
Data Mining ◽  
Decision Tree ◽  
Tight Gas ◽  
Gas Reservoirs ◽  
Tight Sandstone ◽  
Gas Reservoir ◽  
Plot Analysis ◽  
Analysis Technique ◽  
Numerous Test ◽  
Decision Tree Method

Numerous test data accumulates in the process of gas reservoir exploration and development, so it is necessary to apply the data mining technology to this process. Influenced by the geologic factors such as structure, deposition and diagenesis, tight sandstone gas reservoir formation types are so diversified that traditional cross-plot analysis technique hardly identify the formation types. In this paper, the formation types of tight sandstone gas reservoir in Daniudi area are successfully identified using the decision tree algorithm of data mining based on hierarchical decomposition theory, facilitating the development of the gas reservoir.

scholarly journals Investigation of a critical choke during hydraulic-fracture flowback for a tight sandstone gas reservoir

2019 ◽  
Vol 16 (6) ◽  
pp. 1178-1190
Author(s):  
Jiachen Huang ◽  
Jinghong Hu ◽  
Wenting Zeng ◽  
Yuan Zhang
Keyword(s):  
Material Balance ◽  
Optimization Method ◽  
Tight Gas ◽  
Fracturing Fluid ◽  
Gas Reservoirs ◽  
Tight Sandstone ◽  
Gas Reservoir ◽  
Tight Gas Reservoirs ◽  
Wellhead Pressure ◽  
Secondary Damage

Abstract Low porosity and permeability in a tight sandstone gas reservoir can cause problems during fracturing. If the fracturing fluid cannot be discharged in a timely fashion after fracturing, the fracturing fluid will move into the deep formation and result in secondary damage. Conversely, if the flowback rate of the fracturing fluid is too high, it will cause the proppant to backflow and reduce the efficiency of fracturing operation. Therefore, it is very important to control the choke sizes and flowback rates for the flowback process of a tight sandstone reservoir. In this study, a model of the time of the closed fracture considering the principle of material balance is built. Subsequently, the relationship between the wellhead pressure and the optimum diameter of the choke at different times is obtained using hydrodynamics and particle dynamics theory. Finally, the proposed optimization method is applied to an actual well from the Xinjiang tight gas reservoirs. Results show that a choke diameter can be reasonably optimized under different wellhead pressures, and that fracturing fluid flows back as much as possible and without proppant backflow. A sound design of a fracturing fluid flowback system is also provided. This study presents the mechanism of post-fracturing management and provides a better understanding of the flowback system in tight gas reservoirs.

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