A Novel “Soundless Cracking Agent Fracturing” for Shale Gas Reservoir Stimulation

Abstract

Abstract-In the hydraulic fracturing process of brittle shale, stress conducting effect of rock matrix is one of the key factors to form a complex fracture network. According to this theory, the experimental study on a novel "Soundless Cracking Agent (SCA) fracturing" was initially carried out. Fracture propogation law on the multistage and simultaneous SCA fracturing of horizontal wells was explored. The fracture morphology was observed for the first time by high-energy CT scanning. The results show that SCA can create fractures by generating huge radial compressing stress and circumferential tensile stress. All weakly consolidated natural fractures and beddings could develop into fracture propagating paths along arbitrary angle. Much flaking debris is also created to prevent fractures from closing and further improves fracture conductivity. For the multistage fracturing, the induced stress caused by the former fractures will reduce the horizontal stress difference, so that for the latter fractures, it is easier to deviate from the preferred fracture plane. The simultaneous fracturing could create high-density fracture zones between two wellbores by fracture interactions between the corresponding segments of the wellbores. The excellent performance of SCA fracturing in laboratory shows great potential and vast development prospects in shale gas reservoir stimulation.Index Terms-Fracturing, horizontal wells, shale gas, soundless cracking agent.

An Alternative to Conventional Rock Fragmentation Methods Using SCDA: A Review

“…This behavior of SCDA can be used for a continuous fracturing process in unconventional gas reservoirs and the disintegration of the SCDA means there will not be any fluid flow obstruction in the well upon fracture completion. In comparison to conventional methods of hydrofracturing, fracturing using SCDA will largely reduce the required large quantities of water, downhole tools, extra fracturing pump trucks and therefore greatly reduces the total operational cost [107]. Unlike in hydraulic fracturing, there will not be any fluid-solid interaction in the rock mass during SCDA fracturing.…”

“…A further development in the possible application of SCDA in shale fracturing for gas recovery has been studied by Guo et al [107]. The experiment was conducted by drilling horizontal boreholes in horizontally and vertically confined shale samples and charging them with SCDA and found that volumetric fracturing with a complex fracture network could be made when multiple boreholes are used to fracture with SCDA.…”

A study on the optimal use of soundless cracking demolition agents in fragmentations of concrete based on the extended finite element method

“…During the cracking process, SCDA slurry is poured into holes predrilled in rock or concrete structures, afterward the tensile stress, generated from the volumetric expansion of SCDA slurry, is responsible for the cracking of the surrounding rock or concrete structures. The soundless cracking technique has been extensively applied in several fields, for example, demolition of rock or concrete structures, 1,3–10 mine excavation, 2,11–14 and unconventional gas exploration 2,15–19 . As a reliable alternative to the traditional demolition methods, this technology is a nonexplosive fracturing method worthy of further study, which can effectively reduce the noise, dust, and vibrations generated in the traditional technology with blasting and percussive removal techniques.…”

The use of acoustic emissions technique in the monitoring of fracturing in concrete using soundless chemical demolition agent

“…oundless chemical demolition agents (SCDAs) have been used during the last decades in the demolition of boulders and concrete structures as well as in open-surface and sub-surface rock excavation, as an effective alternative to the use of explosives posing safety risks [1][2][3][4][5]. Recently, the potential application of SCDA fracking in unconventional oil and gas recovery as well as in mineral processing applications has been under investigation [5,6]. The effect of the non-S explosive cracking agents on fracturing of the surrounding media inside a borehole is based on the volume thermal expansion of the cracking agent, caused by the exothermic hydration reaction of CaO under confined conditions.…”