Experimental and numerical study of membrane properties and pore pressure transmission of Ghom shale

Summary Understanding the cement hardening process and determining the development of the state of stress in the cement under specific downhole conditions are challenging but fundamental requirements to perform an accurate prediction of wellbore integrity. As an essential component of the state of stress, the temporal variation of cement pore pressure is a critical factor that affects the occurrence of cement failure. In this study, we present a novel laboratory setup to measure the cement pore pressure variation during hardening under representative downhole conditions, including the pressure, temperature, and water exchange between the cement and formation. The pore pressure measurements are further incorporated with a staged finite element analysis (FEA) approach to investigate the state of stress development during cement hardening and to evaluate cement failure under different operations and after different wait-on-cement (WOC) periods. The laboratory measurements show that the external water supply from the formation significantly impedes the pore pressure drop in the cement. The numerical results indicate that the accelerated pore pressure decrease obtained without considering downhole conditions elevates the contact pressure at the cement-formation interfaces significantly and moderately increases the von Mises stress in the cement. The numerical results further predict that the accelerated pore pressure decrease leads to an overestimation of shear failure during pressure testing and steamflooding operations but an underestimation of debonding failure during severe fluid loss and injection-related cooling processes. Based on the results of the integrated laboratory and numerical approach, qualitative and quantitative suggestions are provided for field operations to inhibit wellbore integrity risk during the wellbore life cycle.

Download Full-text

Using time-lapse seismic amplitude data to detect variations of pore pressure and fluid saturation due to oil displacement by water: a numerical study based on one-dimensional prestack inversion

Journal of Geophysics and Engineering ◽

10.1088/1742-2132/3/2/009 ◽

2006 ◽

Vol 3 (2) ◽

pp. 177-193 ◽

Cited By ~ 2

Author(s):

Omar J Varela ◽

Carlos Torres-Verdín ◽

Mrinal K Sen ◽

Indrajit G Roy

Keyword(s):

Pore Pressure ◽

Numerical Study ◽

Time Lapse ◽

One Dimensional ◽

Seismic Amplitude ◽

Oil Displacement ◽

Fluid Saturation ◽

Prestack Inversion ◽

Amplitude Data

Download Full-text

Preparation and Characterization of Latex Particles as Potential Physical Shale Stabilizer in Water-Based Drilling Fluids

The Scientific World JOURNAL ◽

10.1155/2014/895678 ◽

2014 ◽

Vol 2014 ◽

pp. 1-8

Author(s):

Junyi Liu ◽

Zhengsong Qiu ◽

Wei’an Huang ◽

Dingding Song ◽

Dan Bao

Keyword(s):

Particle Size ◽

Particle Size Distribution ◽

Methyl Methacrylate ◽

Size Distribution ◽

Pore Pressure ◽

Water Medium ◽

Gravimetric Analysis ◽

Latex Particles ◽

Pressure Transmission ◽

Ft Ir

The poly(styrene-methyl methacrylate) latex particles as potential physical shale stabilizer were successfully synthesized with potassium persulfate as an initiator in isopropanol-water medium. The synthesized latex particles were characterized by Fourier transform infrared spectroscopy (FT-IR), particle size distribution measurement (PSD), transmission electron microscopy (TEM), and thermal gravimetric analysis (TGA). FT-IR and TGA analysis confirmed that the latex particles were prepared by polymerization of styrene and methyl methacrylate and maintained good thermal stability. TEM and PSD analysis indicated that the spherical latex particles possessed unimodal distribution from 80 nm to 345 nm with the D90 value of 276 nm. The factors influencing particle size distribution (PSD) of latex particles were also discussed in detail. The interaction between latex particles and natural shale cores was investigated quantitatively via pore pressure transmission tests. The results indicated that the latex particles as potential physical shale stabilizer could be deformable to bridge and seal the nanopores and microfractures of shale to reduce the shale permeability and prevent pore pressure transmission. What is more, the latex particles as potential physical shale stabilizer work synergistically with chemical shale stabilizer to impart superior shale stability.

Download Full-text

Experimental Study on the Distribution of Wave-Induced Excess Pore Pressure in a Sandy Seabed around a Mat Foundation

Journal of Marine Science and Engineering ◽

10.3390/jmse7090304 ◽

2019 ◽

Vol 7 (9) ◽

pp. 304

Author(s):

Yuan ◽

Liao ◽

Zhou

Keyword(s):

Pore Pressure ◽

Numerical Study ◽

Experimental Results ◽

Excess Pore Pressure ◽

Offshore Platforms ◽

Pressure Area ◽

Mat Foundation ◽

Mat Foundations ◽

Wave Induced ◽

Excess Pore

Mat foundations are widely used in jack-up offshore platforms to support and transfer loads. Regarding mat foundations working on the seabed, the excess wave-induced pore pressure is critical to seabed stability, which may finally cause structural failure. Therefore, it is important to investigate the distribution of the excess pore pressure in the seabed around the mat foundation. In this study, experiments were performed to study the excess pore pressure distribution around a mat foundation in scale considering the true load state by recording wave profiles and pore pressures inside a sandy seabed. To guarantee the reliability of experiments, a numerical study was conducted and compared with the experimental results. Experimental results indicate that with the existence of the mat foundation, the excess pore pressure is higher at the region, the range of which is the width of the model mat (Wm) before the structure. The maximum pore pressure appears at 0.55 Wm in front of the center of the mat foundation. In addition, the current significantly increases the range of high pore pressure area and the amplitude of the excess pore pressure. As the mat orientation changes, the position of the maximum pore pressure changes from the front to the edge of the mat.

Download Full-text