Case Study of Successfully Staged Acid Fracturing on the Ultra-Deep Horizontal Well for the Qixia Fm HTHP Tight Carbonate Gas Reservoir in China

Liu, Fei; Yang, Fan; Li, Li; Li, Jinsui; Chen, Yan; Lv, Zefei; He, Tingting

doi:10.3389/fenrg.2022.917740

Cited by 2 publications

(1 citation statement)

References 47 publications

(36 reference statements)

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“…By adding a variety of additives to the acid fluid, the rheology of the acid fluid system is changed, and the liquid filtration and acid-rock reaction rate are reduced. Liu et al [17] experimentally tested the reaction rates of three different acid fluid systems: conventional acid, diverting acid, and gelled acid. The experimental results show that the gelled acid with better reaction rate delay effect and lower friction can produce longer acid etched fractures and conductivity.…”

Section: Introductionmentioning

confidence: 99%

Study on Optimization of Stimulation Technology of Heterogeneous Porous Carbonate Reservoir

Zhao,

Xu,

Wang

et al. 2024

Processes

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Mishrif (M) reservoir of Faihaa (F) oilfield in Iraq is a heterogeneous porous carbonate reservoir. The reservoir properties of each reservoir unit differ greatly, and the distribution of porosity and permeability is non-uniform. Some reservoir units have the problem that the expected production cannot be achieved or the production decline rate is too fast after matrix acidification. This work optimized and compared the process of acid fracturing and hydraulic fracturing techniques. The Mishrif B (MB) and Mishrif C (MC) layers are selected as the target units for fracturing and the perforation intervals are optimized. The acid fracturing process adopted the acid fracturing technology of guar gum pad fluid and gelled acid multi-stage injection. According to the wellhead pressure limit and fracture propagation geometry, the pumping rate is optimized. The recommended maximum pumping rate of acid fracturing is 5.0 m3/min, and the optimized acid volume is 256.4 m3. The pressure changes during hydraulic fracturing and acid fracturing are different. It is recommended that the maximum hydraulic fracturing pump rate is 4.5 m3/min for MB and MC layers, and the amount of proppant in MB and MC layers is 37.5 m3 and 43.7 m3, respectively. The production prediction of two optimized processes is carried out. The results showed that the effect of acid fracturing in MB and MC layers is better than hydraulic fracturing, and it is recommended to adopt acid fracturing technology to stimulate MB and MC layers. Acid fracturing operation is carried out in the X-13 well, and better application results are achieved. The results of this study provide optimized reference ideas for reservoir stimulation in heterogeneous porous reservoirs.

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Section: Introductionmentioning

confidence: 99%

Study on Optimization of Stimulation Technology of Heterogeneous Porous Carbonate Reservoir

Zhao,

Xu,

Wang

et al. 2024

Processes

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Analysis of Changes in the Stress–Strain State and Permeability of a Terrigenous Reservoir Based on a Numerical Model of the Near-Well Zone with Casing and Perforation Channels

Chernyshov,

Popov,

Wang

et al. 2024

Applied Sciences

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A finite element model, which includes reservoir rock, cement stone, casing, and perforation channels, was developed. The purpose of the study is to create a geomechanical model of the zone around the well, which includes support elements and perforation channels. This model will help predict changes in the productivity coefficient of a terrigenous reservoir and determine the most efficient mode of operation of a producing well. In order to exclude the stress concentration within the casing–cement stone and cement stone–rock, the numerical model applies contact elements. As a result, structural elements slip, while the stresses are redistributed accurately. The numerical simulation of a stress state in the near-well zone was carried out by using the developed model with differential pressure drawdown on the terrigenous reservoir, one of the oil fields in the Perm region. It is shown that the safety factor of the casing reaches roughly 3–4 units. The only exceptions are the upper and lower parts of the perforations, where this parameter is close to one unit. The safety factor of cement stone accounts for 2–3 units. However, parts with its lowest value (1.35) are also concentrated near the perforation channels. In order to analyze the change in permeability, the dependence of the safety factor on effective stresses was taken into account. Therefore, it was found that, in the upper and lower parts of perforations, the stresses decreased, while permeability rose by up to 20% of the initial value. An increase in differential pressure drawdown, on the contrary, can lead to a permeability reduction of 25%, especially in the lateral parts of the perforations. Areas of rock destruction under tensile and compressive forces were identified by using the Mohr–Coulomb criterion. It is estimated that with an increase in pressure drawdown, the areas of rock destruction under tensile force disappear, while the areas of rock destruction under compression increase. After further analysis, it was found that, with the maximum pressure drawdown of 12 MPa, the well productivity index can decrease by 15% due to the reservoir rock compaction.

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Case Study of Successfully Staged Acid Fracturing on the Ultra-Deep Horizontal Well for the Qixia Fm HTHP Tight Carbonate Gas Reservoir in China

Cited by 2 publications

References 47 publications

Study on Optimization of Stimulation Technology of Heterogeneous Porous Carbonate Reservoir

Study on Optimization of Stimulation Technology of Heterogeneous Porous Carbonate Reservoir

Analysis of Changes in the Stress–Strain State and Permeability of a Terrigenous Reservoir Based on a Numerical Model of the Near-Well Zone with Casing and Perforation Channels

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