Flocculation Drilling

The common process for drilling with clear water is to utilize the reserve pits as a settling pond and inject flocculent downstream from the shale shaker. While proven effective, the traditional reserve pit flocculation process uses a significant volume of water and subsequently a significant volume of chemical to treat it. The BOS patented tank process is a closed loop approach. Drilling fluid is diverted to the BOS tank from the shale shaker and flocculent is added in precise doses to the fluid as it travels to the centrifuge. The fluid over-flow from the centrifuge re-enters the BOS tank system where it flows from cell to cell gently rolled in each cell and slowly spilling over each cell weir. As solids flocculate and drop out of the clarified fluid, they settle on the bottom of the cells where they are pushed back toward the centrifuge suction using directed flow from a mud gun. This directed flow at the bottom of each compartment serves to control the rolling action above it. The solids are taken into the centrifuge for further dewatering with dry solids deposited in a shale bin-waste tank and clear water fed back into the active system. An attractive feature of the BOS tank system is that it is self cleaning; no vacuum trucks are required at any stage of the operation.

Closed Loop (Pitless) Drilling

The term closed loop drilling refers to a tightly controlled drilling fluid and waste management process that eliminates the need for reserve pits and reduces both the amount of fluid required for drilling and the overall environmental footprint. Drilling fluid, drill solids and drill cuttings are all contained and are processed in an environmentally responsible way. In order for Closed Loop Drilling to be effective the fluid management system must be able to deliver accurate control of the mud's density, a function of removing drilled solids from the active mud system while maintaining the rheological properties of the drilling mud. The BOS System provides the most complete solution for closed loop drilling applications. The system is able to perform accurate density control services, accommodate flocculation water drilling sections, and dewater end of section / end of hole mud, all with our standard one skid system. With open loop systems, mud density is controlled with a dump and dilution process releasing volumes of solids laden active mud into the reserve pits and replacing the disposed volume with new water for new drilling fluid. On shallow, fast wells this open loop process can be very cost effective.

Mud and Slurry Dewatering

Dewatering a water based mud system utilizes much the same processes as flocculation drilling. Bentonite and drilled solids are removed from the water through a combination of flocculation and centrifuge decanting. The BOS tank cells are allocated for either dewatering or solids control and both processes take place simultaneously. This split allocation is particularly advantageous as the drilling operation closes in on total depth or the end of a hole section and the mud system needs to be dewatered for disposal and the water reclaimed for subsequent wells. The BOS dewatering process is used both at the drilling location as part of the wellsite fluid management program or at a central dewatering site in the case of a multi-well drilling project.

Barite Recovery

To deal with high pressure wells or unstable formations, the density of drilling fluid systems may need to be increased via the addition of barite. As with all drilling fluids the fine drilled solids begin to build up, negatively affecting the rheology of the drilling fluid and increasing the fluid density. The challenge is to remove the drill solids from the active system while preserving the barite. This is accomplished using two centrifuges. One centrifuge is run at a lower speed to remove the barite and the other centrifuge run at a higher speed to remove the drill solids. The barite recovered from the low speed centrifuge is returned to the active system and the liquid fed to the high speed centrifuge for further processing. The drill solids removed by the high speed system are directed into the shale bin for disposal and the fluid is returned to the active system. This process works equally well with water based or oil based systems.

Cuttings Drying

Oil based muds (OBM) provide a number of advantages to the drilling process. The properties of OBM are such that they offer excellent protection against formation damage. Water based muds react with shale and silt causing it to swell and become less stable. These muds also have a tendency to form emulsions with the liquid phases of hydrocarbons causing near wellbore damage to producing formations. OBM is not absorbed by shales and clays and as a result serves to deliver a better quality bore hole due to minimal washout and minimum formation damage. A further advantage of OBM is it's ability to be formulated at densities below that of water based muds. This provides an opportunity to lower the pressure exerted by the fluid column improving rates of drilling penetration. BOS Solutions plays a key role in the OBM drilling process utilizing our centrifuges to maintain accurate and low fluid density.The one drawback of OBM is its environmental liability. The majority of water based muds are mostly comprised of environmentally benign components; fresh water, bentonite and calcium that can be easily disposed of, OBM has more complex issues. OBM is both costly to purchase and costly to dispose of the residuals. As such, the goal in drilling projects is to recover and reuse OBM's base components. In order to maximize the recovery of OBM and minimize the waste disposal volumes, cuttings produced while drilling with OBM must be processed or "dried". BOS Solutions, utilizing our flexible tank configuration has developed a relatively simple process to achieve this. In a continuous process, drill cuttings are taken from the shale shaker, mixed with a volume of OBM to form a slurry then pulled through an industrial grinder to reduce the cutting size to accommodate the centrifuge process. This slurry with the cuttings is then fed into a powerful centrifuge and a significant amount of OBM recovered and returned to the active mud system. The dried solids are diverted to a cuttings bin for disposal. Simultaneous to the drying process, a second centrifuge is used to remove fine drill solids from the active mud system to accurately control mud density. It is important to mention that the BOS approach to cuttings drying differs from most of our competitors. Our process recovers more OBM than conventional screen dryers, augers and hi-G dryers.