As private companies, groups, organizations, and governments face increasing demand for energy and fuel, interest in geotechnical engineering and technology continues to expand. Liquid drilling fluids and their properties are just a portion of the areas of interest, but the at-line analysis of size and distribution of particles in an aqueous drilling fluid (mud) is an important factor when discussing fluids.

The core FlowCAM technology is currently employed and used worldwide for multiple applications using dynamic image analysis technology. However, increased demand for rig-site real-time detection of particle concentration in drilling fluid has led to the development of the FlowCAM Engineered System (ES).

Sample analysis

A FlowCAM-ES and proprietary VisualSpreadsheet software were used for this experiment. The main components of this customizable system include fluid handling, optics, and electronics (Figure 1). The instrument was configured for the analysis of the sample drilling fluid with four-time magnification and a 600-micron (µ) deep flow cell.

The experimental method used an aqueous sample with primarily calcium carbonate (CaCO) particles to mimic additives in drilling mud. After the addition of CaCO, the sample fluid was recirculated in a closed-loop system until the CaCOand the fluid reached a state of equilibrium. A supply pipe ran from the main storage vessel to the instrument manifold and then returned to the storage vessel.

The sample fluid was actively pumped unidirectionally through the closed-loop system. At regular programed intervals the instrument would draw off sample fluid from the manifold into the instrument where it was automatically diluted and analyzed.

The post-analysis sample fluid was then returned to the manifold, thus rejoining the main sample fluid stream (and not creating a waste stream). Alternatively, the post-analysis sample fluid can be redirected to a secondary waste container for logging or other testing.

An analysis of the sample fluid was conducted to establish the initial particle concentration. A sample of CaCOwas added over time to the fluid system. This sample addition was selected to copy one of the standard processes that occurs to drilling fluids in the field (i.e., the addition of various types of compounds and chemicals to a drilling fluid to change the characteristics of that fluid for optimized drilling operations).

The sample fluid was continuously analyzed to obtain the new particle size distribution D-value trends along with particle images (Figure 2).

Data and results

During analysis of the sample, the instrument displays the resulting information on a real-time basis. In Figure 3 the top right window is a display of the camera’s field of view, with captured particle images in the lower right window and real-time graphs and statistics in the left window. During analysis, the operator can display up to four different graphs, view the count and particles per milliliter (ml) values, and display more than 30 particle properties in the analysis summary statistics area.

An additional graph that can be displayed during the analysis is the time series plot. This graph can be selected to display frequency, parts per million, particles/ml, or an average diameter plot. As the sample is analyzed, the graph automatically updates with the current information. The operator not only can view the data on the main window but also can monitor the time series graph during the analysis for additional trends.

At the end of the analysis the data from these histograms can be exported for further statistical analysis.

At the end of the fluid analysis the operator has a large amount of data that are displayed in an easy-to-read format. The information that is critical to the operator (to make correct decisions regarding optimization of the drilling fluid) can be quickly reviewed.

If any abnormalities or outliers are observed in the various graphs or summary statistics, the operator has the ability to then access and view the actual images of every particle from that analysis. For example, the added feature of particle images can be used to rapidly distinguish between a single 80-µ particle versus two 40-µ particles that have aggregated.

Depending on the desired final composition of the drilling fluid, this extra visual information can save both time and money. Extraneous or potentially ineffective drilling fluid treatments can be avoided, modified, or even eliminated from the overall drilling process.

Conclusions

The data presented in Figure 3 indicate that after the addition of a sample of CaCOparticles, the system can automatically detect and quantify the resulting change to the sample fluid particle size distribution. The resulting data are reported to the operator immediately.

With the data provided by the system, the potential negative effects of incorrect and improper drilling fluid composition on both operational performance and the overall economic situation can be minimized and managed. One other benefit of having near-instantaneous feedback on both size and particle distribution (at the work site or rig) is for drilling fluid modifications.

The resulting data will allow informed decisions concerning these modifications and the proper use of drilling fluids. Finally, in conjunction with particle size and distribution data, the system also provides other data for each analysis (including count, particles/ml, and more than 30 other calculated particle properties).

In summary, the FlowCAM-ES was able to automatically analyze and image the CaCOparticle size and distribution changes in real time.

References available on request.