Substantiation of application of the technology of acid hydraulic facing insea shelfgas condensate carbonate reservoirs

2020 ◽  
pp. 60-67
Author(s):  
R.U. Rabaev ◽  
◽  
R.N. Bakhtizin ◽  
S.Kh. Sultanov ◽  
V.I. Smurygin ◽  
...  
Keyword(s):  
Hydraulic Fracturing ◽  
Flow Rate ◽  
Gas Condensate ◽  
Carbonate Reservoirs ◽  
Mining Equipment ◽  
Acid Fracturing ◽  
Effective Application ◽  
Optimal Technology ◽  
Production Conditions

The article discusses the problems of effective application of acid hydraulic fracturing (HF) technologies in carbonate reservoirs. The optimal technology of acid fracturing has been substantiated, adapted to the geological and production conditions of the development of productive deposits and mining equipment of a gas condensate field of the sea shelf. The results of the design and calculation of the predicted flow rate for specific geological and production conditions of candidate wells are presented.

scholarly journals THE TEST RESULTS OF LOW-PERMEABILITY SHALE DEPOSITS WHEN DRILLING THE PRE-CRETACEOUS COMPLEX AT THE KARMALINOVSKOYE GAS CONDENSATE FIELD

2019 ◽  
pp. 45-58
Author(s):  
A. A. Zakharov ◽  
S. V. Korotkov ◽  
A. I. Gritsenko ◽  
R. A. Ivakin ◽  
V. G. Griguletsky
Keyword(s):  
Hydraulic Fracturing ◽  
Flow Rate ◽  
Gas Condensate ◽  
Low Permeability ◽  
Test Results ◽  
North West ◽  
The North ◽  
Exploratory Wells

The article reports the results of the analysis of the field prospecting activities of five exploratory wells at the Karmalinovskoye gas condensate field. We have found that the eastern part of the licensed area is characterized by the lack of fructuring in Paleozoic deposits, and the development of the productive deposit extends in the north-west direction. Hydraulic fracturing made it possible to get a stable gas and gas condensate flow rate in well № 4. This volume exceeds 3,8 times as large than flow rate in wells № 1 and № 2, which were tested after drilling without conducting hydraulic fracturing.

Well Performance Evaluation of Carbonate Reservoirs After a Novel Hybrid Volume Stimulation Treatment

2021 ◽  
Author(s):  
Jie Zeng ◽  
Jianchun Guo ◽  
Jichuan Ren ◽  
Fanhua Zeng ◽  
Bo Gou ◽  
...  
Keyword(s):  
Hydraulic Fracturing ◽  
Transient Regime ◽  
Carbonate Reservoirs ◽  
The Other ◽  
Fracture System ◽  
Well Performance ◽  
Acid Fracturing ◽  
Complex Fracture ◽  
Rate Behavior ◽  
Primary Fracture

Abstract A large proportion of gas and oil resources are trapped in carbonate reservoirs. Efficient development of these formations is crucial for world energy supply. Recently, a novel hybrid volume stimulation (HVS) technique has been proposed and enhanced carbonate reservoir production in the Bohai Bay Basin and the Ordos Basin of China (Cai et al., 2015; Chu, 2017). This technique involves three stages, including pad-fluid fracturing (primary fracture and fracture branch initiation), massive acid fracturing (acid etching and connection of natural and induced fractures), and proppant injection (conductivity maintenance). Compared with conventional acid fracturing, HVS generates a more complex fracture system by taking the advantage of both hydraulic fracturing and acid fracturing, mitigating high-temperature effects, and increasing the acid penetration distance. Currently, no existing models can predict the pressure and rate behavior of wells after HVS treatments due to the complex fracture geometry and the complicated flow pattern. This study presents a multi-region linear flow model to facilitate evaluating well performance of carbonate reservoirs after HVS and obtaining a better understanding of key factors that control well responses. The model incorporates the fundamental characteristics of the complex fracture system generated by HVS. The primary hydraulic fracture is characterized by two flow regions. One is for the propped primary fracture segment (region 1), while the other represents the unpropped but acid-etched primary fracture tip (region 2). The region adjacent to the primary fracture (region 3) denotes acid-etched fracture branches. Because the acid usually cannot fully penetrate the hydraulic-fracturing-induced branches, the fractal theory is employed to depict the properties of the small fracture branches beyond the acid-etched sections. Finally, the unstimulated reservoir is described by a dual-porosity region (region 4) with vug and matrix systems. Specifically, triple-porosity region 3 contains two possible flow scenarios: one is from vugs to matrices, to fracture branches, and to the primary fracture, while the other is from vugs to matrices, and to the primary fracture. Two weighting factors are utilized to describe the proportion of reservoir volume that is involved in the two fluid flow scenarios. These flow regions are coupled through flux and pressure continuity conditions. The degenerated form of this model is verified against a published analytical model. A good agreement has been achieved between the results of the two models. Analysis results show that four flow regimes can be identified in the log-log type curve. Compared with classical type curves of fractured wells, there is a distinctive fracture-branch-affected transient regime in the pressure derivative curve with a slope between one-half and unity. The HVS generated complex fracture system enhances well productivity from the inter-porosity flow regime to the late fracture-branch-affected transient regime. The impacts of various fracture and reservoir properties on pressure and rate behavior are also documented.

Basic aspects of using acid gel for propant injection during fracturing works in carbonate reservoirs in the Volga-Ural region

2020 ◽  
pp. 33-41
Author(s):  
Gen.G. Gilaev ◽  
◽  
M.Ya. Khabibullin ◽  
G.G. Gilaev ◽  
◽  
...  
Keyword(s):  
Hydraulic Fracturing ◽  
Ural Region ◽  
Carbonate Reservoirs ◽  
Acid Fracturing ◽  
Geological Conditions ◽  
The Difference ◽  
Acid Gel ◽  
Volga Ural Region

In JSC Samaraneftegaz, in recent years, there has been a steady trend towards a reduction in the proportion of proppant fracturing and an increase in the proportion of acid stimulation. After analyzing the previously performed hydraulic fracturing works on the carbonate reservoirs of Samaraneftegaz JSC, as well as world experience, it can be assumed that an increase in the duration of the effect of hydraulic fracturing in carbonate reservoirs can be achieved through a combination of acid fracturing with the use of a proppant (proppant) , where a crosslinked acid gel can serve as the main sand-carrying fluid. However, due to the difference in the geological conditions of carbonate reservoirs, on which the experience of using acid gel as the main sand-carrying agent was considered, the feasibility of using proppant fracturing technology on a cross-linked acid gel requires a set of studies.

Getting Your Perforations in a Line Can Mean More-Productive Fracturing

2021 ◽  
Vol 73 (07) ◽  
pp. 18-21
Author(s):  
Stephen Rassenfoss
Keyword(s):  
Hydraulic Fracturing ◽  
Flow Rate ◽  
Test Results ◽  
Choked Flow ◽  
Target Angle ◽  
High Side ◽  
Treat All ◽  
Estimated Ultimate Recovery

Want more production from a shale well? Consider lining up the perforations. A handful of speakers at the recent SPE Hydraulic Fracturing Technology Conference talked about improved fracturing results with oriented perforating—shooting the holes at the same place in the casing, often the top. This breaks from designs that arranged the holes in a helical pattern with each charge angled 60° from the previous one. “We did see indications we are getting better production from oriented perforating,” said Blake Horton, senior completions engineer for Ovintiv (SPE 204177). Production gains were also reported by ConocoPhillips which compared production from similar wells with and without oriented perforating. The analysis was designed to filter out differences in the geology, drilling, and completions. It concluded the value of the added production far exceeded the $20,000-per-well cost of installing the assembly, including a weight bar to tilt the perforating guns into position. “That’s less than the undiscounted value of 400 barrels of oil. An internal study indicated that ConocoPhillips improved estimated ultimate recovery (EUR) by a minimum of 5% when using high-side-oriented perforating,” said Dave Cramer, senior engineering fellow at ConocoPhillips and an early advocate for the method. “For an initial choked flow rate of 1,000 B/D, the payout on investment is 10 days or less,” he said. Ovintiv declined to provide a number, but Horton said ConocoPhillips’ estimate is within Ovintiv’s range based on similar comparisons of wells with and without oriented perforating. That number is at the low end of the estimates offered in discussions about oriented perforating performance at the conference. Higher estimates are questioned by those who doubt the test results can be sustained when the method is scaled up. What was certain is the number of users is rising and includes names such as Shell and Chevron. “We found that oriented perforating definitely helps to treat all the clusters,” said Jon Snyder, a staff completion engineer for ConocoPhillips who presented the paper, adding, “by oriented perforating we mean that when we are perforating, we aim for the high side of the wellbore” (SPE 204203). When Horton polled the audience at a recent talk, more than half of the respondents said they were using gun systems designed to orient the perforating charges at a target angle. “A year from now, few people will not be doing oriented perforating; the advantages of it are clear,” Cramer said. He has been promoting the idea within the company for years with mixed acceptance.

scholarly journals Analysis of Flow Behavior for Acid Fracturing Wells in Fractured-Vuggy Carbonate Reservoirs

2018 ◽  
Vol 2018 ◽  
pp. 1-20 ◽  
Author(s):  
Mingxian Wang ◽  
Zifei Fan ◽  
Xuyang Dong ◽  
Heng Song ◽  
Wenqi Zhao ◽  
...  
Keyword(s):  
Composite System ◽  
Numerical Solutions ◽  
Transient Flow ◽  
Flow Behavior ◽  
Outer Region ◽  
Carbonate Reservoirs ◽  
Single Fracture ◽  
Specific Flow ◽  
Type Curves ◽  
Acid Fracturing

This study develops a mathematical model for transient flow analysis of acid fracturing wells in fractured-vuggy carbonate reservoirs. This model considers a composite system with the inner region containing finite number of artificial fractures and wormholes and the outer region showing a triple-porosity medium. Both analytical and numerical solutions are derived in this work, and the comparison between two solutions verifies the model accurately. Flow behavior is analyzed thoroughly by examining the standard log-log type curves. Flow in this composite system can be divided into six or eight main flow regimes comprehensively. Three or two characteristic V-shaped segments can be observed on pressure derivative curves. Each V-shaped segment corresponds to a specific flow regime. One or two of the V-shaped segments may be absent in particular cases. Effects of interregional diffusivity ratio and interregional conductivity ratio on transient responses are strong in the early-flow period. The shape and position of type curves are also influenced by interporosity coefficients, storativity ratios, and reservoir radius significantly. Finally, we show the differences between our model and the similar model with single fracture or without acid fracturing and further investigate the pseudo-skin factor caused by acid fracturing.

Study on Acid Fracturing Technology for Carbonate Reservoirs in Ordos Basin

2021 ◽  
Author(s):  
Lufeng Zhang ◽  
Jianye Mou ◽  
Shicheng Zhang ◽  
Mu Li ◽  
Minghui Li
Keyword(s):  
Ordos Basin ◽  
Carbonate Reservoirs ◽  
Acid Fracturing

Modeling Acid Fracturing Treatments with Multi-Stage Alternating Injection of Pad and Acid Fluids

2021 ◽  
Author(s):  
Rencheng Dong ◽  
Mary F. Wheeler ◽  
Hang Su ◽  
Kang Ma
Keyword(s):  
Viscous Fingering ◽  
High Viscosity ◽  
Carbonate Reservoirs ◽  
Acid Etching ◽  
Fracture Geometry ◽  
Fracture Conductivity ◽  
Acid Fracturing ◽  
Fracture Surfaces ◽  
Low Viscosity ◽  
Multi Stage

Abstract Acid fracturing technique is widely applied to stimulate the productivity of carbonate reservoirs. The acid-fracture conductivity is created by non-uniform acid etching on fracture surfaces. Heterogeneous mineral distribution of carbonate reservoirs can lead to non-uniform acid etching during acid fracturing treatments. In addition, the non-uniform acid etching can be enhanced by the viscous fingering mechanism. For low-perm carbonate reservoirs, by multi-stage alternating injection of a low-viscosity acid and a high-viscosity polymer pad fluid during acid fracturing, the acid tends to form viscous fingers and etch fracture surfaces non-uniformly. To accurately predict the acid-fracture conductivity, this paper developed a 3D acid fracturing model to compute the rough acid fracture geometry induced by multi-stage alternating injection of pad and acid fluids. Based on the developed numerical simulator, we investigated the effects of viscous fingering, perforation design and stage period on the acid etching process. Compared with single-stage acid injection, multi-stage alternating injection of pad and acid fluids leads to narrower and longer acid-etched channels.

Transient Pressure Behavior of Acid Fracturing Well in Tidal Flat Carbonate Reservoirs

2018 ◽  
Author(s):  
Wenyang Shi ◽  
Yuedong Yao ◽  
Shiqing Cheng ◽  
He Li ◽  
Naichao Feng ◽  
...  
Keyword(s):  
Tidal Flat ◽  
Carbonate Reservoirs ◽  
Transient Pressure ◽  
Acid Fracturing ◽  
Pressure Behavior

scholarly journals An Investigation into Sub-Critical Choke Flow Performance in High Rate Gas Condensate Wells

Energies ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3992
Author(s):  
Nasriani ◽  
Khan ◽  
Graham ◽  
Ndlovu ◽  
Nasriani ◽  
...  
Keyword(s):  
Flow Rate ◽  
Parameter Variation ◽  
Gas Condensate ◽  
The Other ◽  
High Rate ◽  
Production Data ◽  
Empirical Correlations ◽  
New Correlation ◽  
Production Wells ◽  
Data Points

There have been some correlations in the literature to predict the gas and liquid flow rate through wellhead chokes under subcritical flow conditions. The majority of these empirical correlations have been developed based on limited production data sets that were collected from a small number of fields. Therefore, these correlations are valid within the parameter variation ranges of those fields. If such correlations are used elsewhere for the prediction of the subcritical choke flow performance of the other fields, significant errors will occur. Additionally, there are only a few empirical correlations for sub-critical choke flow performance in high rate gas condensate wells. These led the authors to develop a new empirical correlation based on a wider production data set from different gas condensate fields in the world; 234 production data points were collected from a large number of production wells in twenty different gas condensate fields with diverse reservoir conditions and different production histories. A non-linear regression analysis method was applied to their production. The new correlation was validated with a new set of data points from some other production wells to confirm the accuracy of the established correlation. The results show that the new correlation had minimal errors and predicted the gas flow rate more accurately than the other three existing models over a wider range of parameter variation ranges.

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