Topic
Drilling fluid invasion
About: Drilling fluid invasion is a research topic. Over the lifetime, 59 publications have been published within this topic receiving 710 citations.
Papers published on a yearly basis
Papers
Patent•
29 Dec 1983TL;DR: In this paper, a core sample is collected from the borehole for scanning by a computerized axial tomographic scanner (CAT) to determine the attenuation coefficients at a plurality of points in a cross section of the core sample.
Abstract: A method of determining the invasion of drilling fluid into a core sample taken from a borehole. A first material is added to the drilling fluid to obtain a first fluid that has an effective atomic number that is different than the effective atomic number of the connate fluids in the rock formation surrounding the borehole. A preserved core sample is collected from the borehole for scanning by a computerized axial tomographic scanner (CAT) to determine the attenuation coefficients at a plurality of points in a cross section of the core sample. The preserved core sample is scanned with a CAT at first and second energies, and the determined attenuation coefficients for the plurality of points in the cross section at each energy are used to determine an atomic number image for the cross section of the core sample. The depth of invasion of the first fluid is then determined from the atomic number image, as an indication of the depth of invasion of the drilling fluid into the core sample.
268 citations
TL;DR: In this article, a method was developed to simulate drilling fluid invasion of a two-phase system (water-based mud in an oil-bearing formation) and to subsequently evaluate the damage along a horizontal well.
42 citations
TL;DR: In this article, a model for radial fluid transport is presented to characterize conductivity profiles due to drilling fluid invasion into a hydrocarbon formation, and a mathematical analysis of the model using the method of characteristics is given.
Abstract: In order to characterize conductivity profiles due to drilling fluid invasion into a hydrocarbon formation, a model for radial fluid transport is presented. The model assumes a water-based mud and accounts for the convective movement of oil, water, and salt. A mathematical analysis of the model using the method of characteristics is given. An equivalent graphical construction is also provided. Computations of radial conductivity profiles for specified formation characteristics and total filtrate loss are given. For typical fractional flow curves, it is shown that three qualitatively different profiles may occur depending on the initial water saturation. These results are compared with numerical simulations that include capillary pressure and gravity segregation. Next, the important issue of the inverse problem is analyzed. It is shown that from a single snapshot of the conductivity profile, an exact calculation of filtrate loss and formation fractional flow curve is possible. The calculation is valid provided there is a resistivity contrast between the drilling fluid filtrate and the formation water. For practical application, we show the limits of applicability of this result with complete numerical calculations. Thus, if wireline logs of resistivity variation away from the wellbore are available, formation oil producibility and water cut at native conditions may be estimated.
42 citations
TL;DR: In this article, a simple but novel NMR technique was presented to evaluate filter cake properties such as thickness, pore volume, porosity, and possibly permeability, and the amount and particle size distribution of solids that invaded a given sample can be obtained using the same technique.
Abstract: An efficient drilling fluid will form a filter cake that will minimize the drilling fluid invasion into any drilled formation. Drilling fluid must therefore be adequately evaluated in the laboratory prior to field trial. Filter cake properties such as thickness, porosity, permeability, and pore structure are frequently evaluated using several techniques such as CT scan, SEM, and XRF. However, each of these techniques can evaluate only one or two filter cake properties. This paper presents a simple but novel NMR technique to evaluate filter cake properties such as thickness, pore volume, porosity, and possibly permeability. Furthermore, the amount and particle size distribution of solids that invaded a given rock sample can be obtained using the same technique. The full procedure was tested and verified using four identical rock samples. Drilling fluid invasion and filter cake deposition experiments were conducted on each of the samples, using the same drilling fluid but four different concentrations of fluid loss additive. NMR T2 relaxation measurements were taken at three different stages of each rock sample: before filter cake deposition; after fluid invasion and filter cake deposition; and after filter cake removal. A material balance analysis of the probability density function and cumulative distribution function of the measured T2 profile at the different stages of each sample yielded multiple filtration loss properties of the filter cake. The results obtained showed high accuracy of the NMR versus the current techniques. Moreover, this current method evaluated the majority of the filter cake properties at the same time and in situ hence eliminated the need of using multi-procedures that disturb the sample state. Finally, the presented method can also be used to evaluate secondary damage associated with filter cake removal process.
40 citations
Journal Article•
TL;DR: In this article, the authors discuss the advantages of using air as the circulating medium over drilling mud and present some disadvantages of air-drilled horizontal wells. But, some of the problems are unique to air drilling, but somemore may be exaggerated by the conditions in an airdrilled hole, such as increased friction between the drillstring and borehole.
Abstract: Drilling horizontal wells with air as the circulating medium is not a common practice; however, air has come distinct advantages over drilling mud. They are: Significant increase in rate of penetration which leads to shorter drilling time. Elimination of lost circulation problems, especially in areas of very low bottom hole pressures. Continual drill stem test of potential producing formations. Minimal damage to the formation. Unfortunately, there are some disadvantages to drilling with air. Downhole motor life is shorter and less predictable. No measurement-while-drilling (MWD) system is currently available that will work consistently in air drilling environments. Hole cleaning is a problem at inclinations above 50{degree}. The horizontal section length is reduced because of the increased friction (drag) between the drillstring and borehole. The types of lithologies and targets are limited. Several horizontal wells have been successfully drilled with air or foam since 1986. At a minimum, operators drill the horizontal section with air or foam to eliminate lost circulation problems in low pressure or partially depleted reservoirs and to reduce formation damage due to drilling fluid invasion. However, problems have been encountered in drilling horizontal wells with air. Not all of the problems are unique to air drilling, but somemore » may be exaggerated by the conditions in an air-drilled hole.« less
32 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2021 | 5 |
| 2020 | 5 |
| 2019 | 5 |
| 2018 | 2 |
| 2017 | 5 |
| 2016 | 2 |