Use of After Closure Analysis to Improve Hydraulic Fracturing Designs, Application on Algeria's In-Adaoui gas Field

2003 ◽  
Author(s):  
S. Benelkadi ◽  
R. Belhaouas ◽  
M. Sahar
2021 ◽  
Author(s):  
Aamir Lokhandwala ◽  
Vaibhav Joshi ◽  
Ankit Dutt

Abstract Hydraulic fracturing is a widespread well stimulation treatment in the oil and gas industry. It is particularly prevalent in shale gas fields, where virtually all production can be attributed to the practice of fracturing. It is also used in the context of tight oil and gas reservoirs, for example in deep-water scenarios where the cost of drilling and completion is very high; well productivity, which is dictated by hydraulic fractures, is vital. The correct modeling in reservoir simulation can be critical in such settings because hydraulic fracturing can dramatically change the flow dynamics of a reservoir. What presents a challenge in flow simulation due to hydraulic fractures is that they introduce effects that operate on a different length and time scale than the usual dynamics of a reservoir. Capturing these effects and utilizing them to advantage can be critical for any operator in context of a field development plan for any unconventional or tight field. This paper focuses on a study that was undertaken to compare different methods of simulating hydraulic fractures to formulate a field development plan for a tight gas field. To maintaing the confidentiality of data and to showcase only the technical aspect of the workflow, we will refer to the asset as Field A in subsequent sections of this paper. Field A is a low permeability (0.01md-0.1md), tight (8% to 12% porosity) gas-condensate (API ~51deg and CGR~65 stb/mmscf) reservoir at ~3000m depth. Being structurally complex, it has a large number of erosional features and pinch-outs. The study involved comparing analytical fracture modeling, explicit modeling using local grid refinements, tartan gridding, pseudo-well connection approach and full-field unconventional fracture modeling. The result of the study was to use, for the first time for Field A, a system of generating pseudo well connections to simulate hydraulic fractures. The approach was found to be efficient both terms of replicating field data for a 10 year period while drastically reducing simulation runtime for the subsequent 10 year-period too. It helped the subsurface team to test multiple scenarios in a limited time-frame leading to improved project management.


2009 ◽  
Author(s):  
Ryohei Kamitsuji ◽  
Ken Nagai ◽  
Yu Matsuno ◽  
Yutaka Ohsaki ◽  
Tetsuya Tamagawa ◽  
...  

2018 ◽  
Author(s):  
Eirik Kårstad ◽  
Yan Zheng ◽  
Akimzhan Lukpanov ◽  
Nariman Abzhanov ◽  
Karl Giesemann ◽  
...  

2020 ◽  
Vol 8 (4) ◽  
pp. T813-T821
Author(s):  
Hailiang Li ◽  
Liping Zhang ◽  
Jinyong Gui ◽  
Hailong Wang ◽  
Shengjun Li

Tight sandstone gas reservoirs have the characteristics of low porosity and permeability, deep burial, and low production of vertical wells, which are difficult to predict and exploit. Usually, finding a “sweet spot” requires finding zones with well-developed fractures or easy stimulation by hydraulic fracturing in the later stage. For some tight sandstone gas reservoirs where natural fractures are not developed, directional hydraulic fracturing is a good choice to improve single well production. However, not all reservoirs can achieve the desired productivity after hydraulic-fracture stimulation. In the exploration of the Sulige (SLG) gas field in Western China, sweet spots with strong brittleness and good petrophysical properties can ensure the success of hydraulic fracturing. We have evaluated the SLG gas field to determine how to implement an engineering-oriented sweet spot prediction workflow. The method has five steps: data-quality analysis, lithology prediction, brittleness prediction, petrophysical property prediction, and well planning. We evaluated the feasibility of subsequent sensitive elastic parameter inversion by comparing the accrual and simulated seismic gathers. Then, we used a direct inversion method of Young’s modulus to predict lithology and identify fluid at the same time. Next, we constructed a new brittleness index by combining the rate of change of Young’s modulus and the quartz content to evaluate the brittleness of rocks, which can overcome the shortage of the conventional brittleness index constructed by a single parameter. Finally, by using the brittleness index, we combined the petrophysical properties inversion results to select regions with strong brittleness and good petrophysical properties as the basis of well planning. This workflow achieved remarkable results in the exploration of tight sandstone gas reservoirs in the SLG gas field in Western China.


2021 ◽  
Author(s):  
Zamzam Mohammed Ahmed ◽  
Abrar Mohammed Alostad ◽  
Liu Pei Wu

Abstract The North Kuwait Jurassic Gas (NKJG) reservoirs pose productivity challenges due to their geological heterogeneity, complex tectonic settings, high stress anisotropy, high pore pressure, and high bottom-hole temperature. Additionally, high natural fracture intensity in clustered areas play an important role in the wells hydrocarbon deliverability. These challenges are significant in field development starting from well design and stimulation up to production stages. The Gas Field Development Group (GFDG) are introducing for the first time in Kuwait new completion designs at high fracturing intensity; open-hole Multi Stage Completions (MSC), 4.5" Monobores and hybrid completions along with customized and efficient stimulation methods. This development strategy designed to overcome reservoir difficulties and enhance the well performance during initial testing and long-term production phases. At early stages of production, most of the wells were stimulated with simple matrix acidizing jobs and this method was sufficient to reach commercial production in conventional reservoirs. However, the reservoir depletion trend has negatively affected stimulation effectiveness and the wells performance in the recent years; hence, short and long-term solutions introduced to manage the sub-hydrostatic reservoir pressure. Our current focus is on the short-term stimulation solutions as they are relatively easier to apply compared to the long-term solutions that require additional resources, which are not available in the country. As a result, the stimulation methods, specifically the hydraulic fracturing treatments, increased production dramatically compared to previous years and it applied across North Kuwait Fields in conventional and unconventional reservoirs to reach the production targets of 2020-2021. The hydraulic fracturing treatment designs improved during the 2020-2021 fiscal year. The number of operations tripled compared to before and alternative chemical treatments with new fracturing designs implemented. In addition, these treatments executed across different well completions and reservoir properties. The objectives behind each fracturing treatment were different; for example: discovering new areas, re-stimulating under-performing wells, fracturing unconventional reservoirs, etc. Some promising wells did not flow as per expectation after matrix acidizing treatments despite the logs showing good reservoir quality similar to offset wells with good production. After re-stimulating with acid fracturing, the wells performed much better and one of them set a benchmark as the best producer amongst the offset wells. This paper evaluates the gaps in developing NKJG reservoirs, including fracturing treatments and highlights of the pros/cons for each operation, which in future supports the improvement of stimulation job designs. Moreover, it reveals the future requirements that control the operation success and how to reduce the well cleaning time post-fracturing in the event of low reservoir pressure. Finally, it describes how the outcome of the analyses directly assists reaching the production targets; since NKJG's production mainly depends on stimulation techniques.


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