Modeling Wormhole Propagation During Closed-Fracture-Acidizing Stimulation in Tight-Carbonate Formations

SPE Journal ◽  
2020 ◽  
Vol 25 (05) ◽  
pp. 2373-2400
Author(s):  
Khaled Aldhayee ◽  
Mahmoud T. Ali ◽  
Hisham A. Nasr-El-Din
Keyword(s):  
Strong Acid ◽  
Closed Fracture ◽  
Fracture Conductivity ◽  
Well Stimulation ◽  
Robust Model ◽  
Tight Carbonate ◽  
Flow Mechanisms ◽  
Computational Fluid Dynamics Cfd ◽  
Carbonate Formations ◽  
Stimulation Technique

Summary Closed-fracture acidizing (CFA) is a well-stimulation technique that can be applied to stimulate carbonate reservoirs at the end of acid-fracturing treatments. In CFA, acid is injected into the closed fracture at rates lower than the fracturing pressure to enhance the fracture conductivity. The objective of this study is to develop a robust model that can capture the dissolution process and wormhole-propagation phenomena that occur during CFA. This work develops a CFA model using computational-fluid-dynamics (CFD) techniques coupled with a two-scale continuum model that can predict accurately the reactive-flow mechanisms of hydrochloric acid (HCl) in carbonate formations. The developed CFA model is constructed and populated with the actual porosity-distribution profiles of tight carbonates. The model was tested against the experimental work performed on a fracture-conductivity apparatus. Sensitivity analysis is performed for several parameters that affect the performance of CFA in tight-carbonate formations. The developed model has successfully captured the dissolution patterns and wormhole-propagation phenomena that occur during CFA. In calcite formations, high temperatures promote acid leakoff into the formation, resulting in inefficient fracture stimulation. On the contrary, low temperatures reduce the overall reaction kinetics and attenuate the HCl reaction with calcite. Also, simulation results show that high acid concentration is favorable in treating low-conductivity fractures. In dolomite formations, it is essential to adapt a strong-acid system with an extended treatment duration to ensure efficient acid stimulation to the closed fractures. This paper provides a simulation study of the CFA process in a carbonates formation by establishing a 3D CFD model using the two-scale continuum approach. Fracture-surface etching and the associated acid-wormhole behavior during CFA are experimentally validated. This study optimizes the acid volumes and injection rates that can be used in conducting CFA.

Needles in the Pay Stack ADNOC Exploring Tight-Oil Rock, Triples Production In First Pilot

2021 ◽  
Vol 73 (01) ◽  
pp. 20-22
Author(s):  
Trent Jacobs
Keyword(s):  
Carbonate Reservoir ◽  
Reservoir Rock ◽  
Abu Dhabi ◽  
Data Set ◽  
Slowing Down ◽  
Tight Carbonate ◽  
Potential Impact ◽  
Carbonate Formations ◽  
Oil Company ◽  
Term Data

In the midst of an industry downturn last year, the Abu Dhabi National Oil Company (ADNOC) reached a new oil production ceiling of 4 million B/D. The UAE’s largest producer has no intentions of slowing down. By decade’s end, ADNOC expects to have raised its maximum daily output by another million barrels. To cross that milestone, the company has set its sights on mastering the tight, thin, and unconventional formations that dot the UAE’s subsurface landscape. One of the places where such developments are hoped to unfold soon is known as Field Q. Found in southeastern Abu Dhabi, Field Q sits above a tight carbonate reservoir that holds an estimated 600 million bbl of oil. But with a permeability ranging from 1 to 3 millidarcy and poor vertical communication, the reservoir and its barrels have proven difficult to cultivate economically - until recently. ADNOC has published new details of its first onshore pilot of a “fishbone stimulation” that involved using more than a hundred hollow needles to pierce as far as 40 ft into the reservoir rock. The additional drainage netted by the fishbone needles boosted production threefold in the test well, as compared with its traditionally completed neighbors on the same pad. ADNOC ran the pilot in the summer of 2019 and by the end of the year saw enough production data to launch a wider 10-well pilot that remains underway. Based on a longer-term data set from these wells, the company will decide whether to leap into a fieldwide deployment of the niche completions technology. In the meantime, the petrotechnical team in charge of the test projects have issued roundly positive reviews of the fishbone technique in two recently presented technical papers (SPE 202636; SPE 203086) from the Abu Dhabi International Petroleum Exhibition & Conference (ADIPEC). “There is a chance that the fishbone-stimulated wells can avoid the drilling of multiple wells targeting different sublayers in the same zone,” said Rama Rao Rachapudi, listing one of several of the technology’s advantages over other approaches that were considered. The senior petroleum engineer with ADNOC, who is one of several authors of the papers that cover both the drilling and completions aspects of the pilot, shared during ADIPEC that his onshore team found motivation to test the technology after bringing in a batch of dis-mal appraisal wells. The fishbone system, also known as multilateral jetting stimulation technology, has been a specialized application ever since it was introduced just over a decade ago. Underscoring the potential impact of the current round of pilots on the technology’s adoption rate, ADNOC noted there were only around 30 worldwide fishbone deployments prior to this project. Most of those have been in the Middle East’s naturally fractured and layered carbonate formations - just like those of Field Q.

Study on a Self-Diverting Acid System for Well Stimulation Based on Novel Visco-Elastic Surfactant

2011 ◽  
Vol 287-290 ◽  
pp. 3120-3126 ◽  
Author(s):  
Fu Jian Zhou ◽  
Chun Ming Xiong ◽  
Yang Shi ◽  
Xian You Yang ◽  
Sheng Jiang Lian ◽  
...  
Keyword(s):  
Oil And Gas ◽  
Carbonate Reservoir ◽  
Scanning System ◽  
Low Permeability ◽  
Acid System ◽  
Core Flooding ◽  
Well Stimulation ◽  
Core Permeability ◽  
Carbonate Formations ◽  
Oil Gas

Carbonate reservoir, widely distributed in china, is an important resource of oil and gas. Most of carbonate reservoir are very tight and need to be stimulated to increase the permeability for the flowing of oil/gas. Acid treatment is a kind of stimulation. However, the ordinary acid system cannot stimulate carbonate reservoir effectively because of the heterogeneity among formations. Based on a novel visco-elastic surfactant, this paper develops a self-diverting acid system (DCA) for carbonate formations. This system had been applied in the treatment of carbonate reservoirs successfully. Experiments studying the diverting mechanism had been conducted with HTHP Rheometer, parallel core flooding system and MRI Scanning system. The results indicate that: the viscosity of reacted acid can reach to 200 times higher than that of fresh acid. The injecting pressure of DCA is 20 times higher than that of ordinary acid (HCl) during the parallel core flooding experiment. MRI scanning images of the cores after acid flooding show that DCA can stimulate the cores with middle and low permeability more effectively. In middle and low permeability cores, the length of wormhole created by DCA is 4-8 times longer than that created by ordinary acid. At the same time, the relationship between flooding pressure and core permeability is also studied. This paper reveals the diverting mechanism of DCA through these experiments.

Application of Closed Fracture Acidizing for Stmulation of Tight Carbonate Reservoir in Mumbai Offshore

2017 ◽  
Author(s):  
Dilip Kumar Sarma ◽  
Tej Pal ◽  
Dileep Kumar ◽  
Gopal Lahiri ◽  
V V Manchalwar
Keyword(s):  
Carbonate Reservoir ◽  
Closed Fracture ◽  
Tight Carbonate

Comprehensive Fracture Characterization in Tight Carbonate Reservoir Using LWD High-Resolution Image and Multi-Pole Sonic Measurement; A Case Study from Offshore North West Java, Indonesia

2021 ◽  
Author(s):  
Debby Irawan ◽  
Icuk Dwi Wibowo ◽  
Bertha Martinauly ◽  
Linda Fransiska ◽  
Leonora Ludwina Lilasari ◽  
...  
Keyword(s):  
High Resolution ◽  
Open Fracture ◽  
Carbonate Reservoir ◽  
Fracture Zones ◽  
Closed Fracture ◽  
Fracture Characterization ◽  
North West ◽  
Tight Carbonate ◽  
Resistivity Log

Abstract Tapping into an unconventional reservoir such as naturally fractured tight carbonate or basement has become more common in the industry. Open natural fractures, when present are the major contributor to production flow in such formation. Therefore, a comprehensive understanding of fracture properties including aperture, intensity, and permeability is required to identify the productive fractures and optimize production. In this paper, we discuss the first application of the latest Logging-While Drilling (LWD) high-resolution laterolog resistivity image in combination with LWD multi-pole sonic to provide comprehensive fracture characterization in Pre-Talang Akar Formation tight carbonate reservoir, in the offshore North West Java Basin, Indonesia. The methodology involved identification of borehole breakouts, natural or drilling-induced fractures, faults and vugs from the high-resolution LWD image data, which were then interpreted further to provide the fracture attributes and the secondary porosity distributions from each of the identified features. The Stoneley measurement from LWD multi-pole sonic log enabled the analysis of the fracture system producibility using the sonic fracture technique. The characterization of fractures and faults (open/closed) from the integration of these two independent methods were complemented by the triple combo measurements, caliper, and drilling loss data, as well as sonic compressional and shear data. This methodology has successfully managed to differentiate open fracture zones and closed fracture zones along with their computed fracture properties. The open fracture zones were characterized by a cluster of conductive fractures with large fracture aperture and fracture porosity value. These fractures were also associated with positive fracture indication from the sonic data, decrease in density logs, shallow - deep resistivity log separation and drilling loss occurrence. Whereas, closed fracture zones were characterized with minor fracture dip development. It also showed negative open fracture indication from sonic data, flat density log response and overlaying resistivity log response with no drilling loss occurrence. The case study in this paper shows excellent LWD data quality and fracture characterization result, on par with wireline conveyed data that were commonly used to quantify fracture attributes. The results provide invaluable information for volumetric calculation, well completion and production planning in this area.

Novel Assessment of Hydraulic Fracturing with Geomechanical Characteristics in Tight Carbonate Formations

2018 ◽  
Author(s):  
Youngho Jang ◽  
Hyunsang Yoo ◽  
Wonmo Sung ◽  
Jeonghwan Lee ◽  
Won Suk Lee
Keyword(s):  
Hydraulic Fracturing ◽  
Tight Carbonate ◽  
Carbonate Formations
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