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Anti-channeling cementing technology for long horizontal sections of shale gas wells

Fig. 1. Diagram of designed and actual well trajectories of Well W204H4-6.

It is indicated that the near-bit three-centralizer drifting BHA used for casing stiffness simulation can decrease the casing running difficulty in the long horizontal section of a shale gas well and increase the time efficiency and safety of casing running; that the flushing efficiency of high-efficiency oil flushing spacer fluid

Adsorption damage and control measures of slick-water fracturing fluid in shale reservoirs

Fig. 1 Experimental integrating shale displacement unit and ultraviolet spectrophotometer.

With the increase of pH value, the adsorption capacity decreased gradually, the adsorption capacity increased first and then decreased with the increase of temperature, and the adsorption capacity was the largest at 45°C. The adsorption patterns of polymers on shale were described by scanning electron microscopy and magnetic resonance imaging.

Shale hydration inhibition characteristics and mechanism of a new amine-based additive in water-based drilling fluids

In this work, shale hydration Inhibition performance of tallow amine ethoxylate as a shale stabilizer in water based drilling fluid, was investigated through these tests: bentonite hydration inhibition test, bentonite sedimentation test, drill cutting recovery test, dynamic linear swelling test, wettability test, isothermal water adsorption test, and zeta potential test.

Some amine functional groups exist in tallow amine ethoxylate structure which are capable of forming hydrogen bonding with surfaces of bentonite particles. This phenomenon decreased the water adsorption on bentonite particles' surfaces which results in reduction of swelling. Tallow amine ethoxylate is also compatible with other common drilling fluid additives. Introduction A

Elastic–Brittle–Plastic Behaviour of Shale Reservoirs and Its Implications on Fracture Permeability Variation: An Analytical Approach

Fig. 1 a Fractures in shale core samples (Gale et al. 2014), b a subvertical calcite-cemented fracture (Soeder 1988), c simplified dual porosity concept for shale

Desorption of gas during production can cause shrinkage of the organic content of the rock. This becomes more important when considering the use of shales for CO2 sequestration purposes, where CO2 adsorption-induced swelling can play an important role. These phenomena lead to changes in the stress state within the rock

Development of a new correlation to determine the static Young’s modulus

Fig. 13 Estimated Young’s modulus value from dynamic one using different correlation, case #2 limestone formation. E new is the static Young’s modulus estimated by the developed correlation, and it gives the best match with the core measured data and the lowest root-mean-square error. a Prediction of static Young’s modulus. b Root-mean-square error

The laboratory values are then used to correlate the dynamic values derived from the logs. Several correlations were introduced in the literature, but those correlations were very specific and when applied to different cases they gave very high errors and were limited to relating the dynamic Young’ modulus with the

Mudcake effects on wellbore stress and fracture initiation pressure and implications for wellbore strengthening

Fig. 1 Schematic of the cross section of wellbore, mudcake, and formation (not to scale)

Numerical examples are provided to illustrate the effects of these mudcake parameters. The results show that a low-permeability mudcake enhances FIP, mainly through restricting fluid seepage and pore pressure increase in the near-wellbore region, rather than by mudcake strength. Fluid loss pressure (FLP) should be distinguished from FIP when a

Preparation and application of melamine cross-linked poly ammonium as shale inhibitor

Fig. 3 The appearance of mud balls immersed in different treatment solutions for 12 h. a Distilled water, b 0.8% DEM-8, c 1.0% KCl, d 0.8% DEM-8 + 1.0% KCl

The inhibition mechanism of DEM-8 was studied by thermogravimetric analysis and scanning electron microscope. The results demonstrate that DEM-8 can be adsorbed on clay surface through electrostatic interaction and hydrogen bonds by an anchoring effect and a hydrophobic effect. Introduction Shale oil/gas has been one of the technologies highlighted in the world

Thermogravimetry as a tool for measuring of fracturing fluid absorption in shales

Fig. 6 Comparison of absorbance capacity of the examined samples. Explanations: 0—blank test—fresh sample, W—distilled water saturated, F—the same sample saturated with fracturing fluid, F2—fresh sample saturated with fracturing fluid

In case of rocks which are drilled from the borehole, obtaining such large samples is very difficult; therefore, an attempt was made to determine the rock absorption on small samples, using the TG analysis. Thermogravimetric (TG/DTG) experiments were conducted in temperature range 40–300 °C in synthetic air environment. Shale rock

Cationic surfactant (CTAB) a multipurpose additive in polymer-based drilling fluids

Fig. 1 FTIR spectrum of CTAB

Addition of cetyltrimethylammoniumbromide increased fluid retention capacity of the fluid even at very low concentration 0.1%(w/v) without affecting the mud properties. Also it is compatible with the commercially available fluid loss preventers like pre-gelatinized starch when used in combination. It also performed well in dissolved oxygen test, suggesting eliminating need

Experimental Study and Numerical Modeling of Fracture Propagation in Shale Rocks During Brazilian Disk Test

Fig. 9 Local damage zone under loading point of specimen A, damage in the specimen and distance from the center of the disk.

To incorporate the effects of shale formation heterogeneity in the simulation of crack paths, fracture properties of the specimens are defined as spatially random fields. A computational strategy on the basis of stochastic finite element theory is developed that allows to incorporate the effects of heterogeneity of shale rocks on

Fracking: How far from faults?

Fig. 4 Map showing the epicentre of the fracking-induced earthquake of 2nd August 2011 (PH Event) in relation to the hypothesised fault which slipped and the orientations of the maximum (SHmax) and minimum (SHmin) horizontal stress directions. Adapted from Clarke et al. (2014).

An alternative approach is to use microseismic data to infer the extent of fracture propagation and stress changes. Using published microseismic data from 109 fracking operations and analysis of variance, we find that the empirical risk of detecting microseismicity in shale beyond a horizontal distance of 433 m is 32%

An integrated approach to discretized 3D modeling of geomechanical properties for unconventional mature field appraisal in the western Canadian sedimentary basin

Fig. 4 a Depth structural map from tops, b 3D grid layers, c Location of wells in the study area and d 3D block configuration.

To overcome these challenges, this paper describes an integrated approach for deriving 3D geomechanical models of the reservoir by combining results of 3D geocellular models and basin models. The basin model reconstructs the geologic history (i.e., burial history) of the reservoir by back-stripping it to the original depositional thickness. Through

The Application of a New Neutron Induced Gamma Ray Spectroscopy Tool in Evaluation the Shale Gas in Fuling Shale Gas Field

Shale gas reservoir is characterized by complex lithology with ultra-low porosity and permeability, which brings many challenges in the formation evaluation. Elemental Capture Spectroscopy Sonde (ECS) can be used to measure the elements and get the formation of the mineralogy. LithoScanner is a newly-generated spectroscopy tool, which can be used to measure both inelastic and capture spectra, providing estimation of more elements, including silicon, calcium, iron, sulfur, titanium, gadolinium, aluminum, potassium, sodium, magnesium, manganese, carbon, etc.

The changing lithology and borehole rugosity have little influence on the direct measurement of TOC by LithoScanner. LithoScanner shows great advantage in accuracy when comparing with other methods using triple-combo. The systematic lithology classification method in shale gas reservoir using LithoScanner is correlatable in multi-wells. The brittleness index from mineralogy

A Novel Energy-Efficient Pyrolysis Process: Self-pyrolysis of Oil Shale Triggered by Topochemical Heat in a Horizontal Fixed Bed

Figure 5: Description of the main phenomena occurring during the propagation of the self-pyrolysis front.

The results show that the self-pyrolysis of oil shale can be achieved with the proposed method without any need for external heat. The results also verify that fractured oil shale may be more suitable for underground retorting. Moreover, the gas and liquid products from this method were characterised, and a

Design and hydraulic modeling of pulse grinding bits for horizontal wells

Fig. 1. Schematic diagram of a Helmholtz pulse grinding bit. Note: 1. Internal grinding chamber; 2. Accelerating chamber; 3. Mixing chamber; 4. Swabbing chamber; 5. Lower jet channel; 6. Helmholtz oscillation chamber; 7. Diffusion chamber; 8. Internal grinding machine; 9. Throat; 10. Reverse high-speed flow channel.

By using this bit, efficient cuttings removal and rock breaking will be both realized, the chip hold-down effect will be reduced and the cuttings beds in a horizontal well will be also removed. Then, the hydraulic models were established for a pulse generation device, an efficient rock breaking device and