Loss Circulation Materials Research Articles

Testing conditions make a difference when testing LCM

Laboratory studies have been used extensively to evaluate loss circulation materials (LCM) treatments to solve or prevent lost circulation problems in fractured formations. Experiments with slotted disks simulating fractures have been performed with the amount of fluid loss and sealing pressure used as evaluation criteria. This study presents the investigation of LCM behavior with different slot designs and fluid flow patterns for water-based and oil-based drilling fluids. Experiments on tapered-slot discs that simulate fractures with different fracture wall angles and fracture lengths were conducted at high pressure. A bladder-type accumulator was added to the system to provide an instantaneous flow condition. Results showed that increasing the wall angle tended to decrease sealing efficiency. Increasing the fracture length (disc thickness) in tapered discs resulted in higher sealing pressure. In the instantaneous flow tests, LCM formulations used to perform a strong seal in slow injection tests also sealed the slot under the sudden flow condition with a similar bridging and sealing profile, but different in the fluid loss volume. This set of experiments shows that the experimental setup can change the results, so caution should be taken when quantitatively comparing LCM tests on slot disks from different experimental setups.

Reducing Lost Circulation Problem by Using Rice Material

Drilling fluid loss during drilling operation is undesirable, expensive and potentially hazardous problem.
 Nasiriyah oil field is one of the Iraqi oil field that suffer from lost circulation problem. It is known that Dammam, um-Radoma, Tayarat, Shiranish and Hartha are the detecting layers of loss circulation problem. Different type of loss circulation materials (LCMs) ranging from granular, flakes and fibrous were used previously to treat this problem. 
 This study presents the application of rice as a lost circulation material that used to mitigate and stop the loss problem when partial or total losses occurred.
 The experimental work included preparing drilling fluid, which is selected to be water based mud. Amount of loss for rock samples was measured where the percentage of losses of drilling mud were 46.25% and 96.96% as well as the percentage of improvement in curing of lost circulation were calculated after rice adding. Rice materials addition was done by tow stages: a) Adding 24 Ib/bbl of fine rice and 1 Ib/bbl of course rice gave improvement in curing from 30.67% to 100%. b) Adding 24 Ib/bbl of fine rice and 6 Ib/bbl of course rice gave an improvement in curing equal to 92.12%. 

Fracture Width Logging While Drilling and Drilling Mud/Loss-Circulation-Material Selection Guidelines in Naturally Fractured Reservoirs

Summary In this article we discuss drilling mud losses in naturally fractured reservoirs with fracture permeability larger than 50 odd md and much larger than the matrix permeability. Type curves are provided that describe mud loss volume vs. time and allow the determination of the hydraulic width of natural fractures through the usual type curve matching technique of log/log plots. Real time logging while drilling of natural fracture width permits the proper selection of loss-circulation material (LCM) with respect to particle size distribution. Efficient (rapid) mud loss control is made possible, increasing the chances of minimizing fracture damage by the drilling mud, the cuttings and the LCMs themselves. The total mud losses experienced when drilling a long horizontal section are shown to agree with reservoir properties (derived by well testing) in particularly well-documented examples of the central North Sea. The equations provided can therefore be utilized as well by reservoir engineers to properly evaluate the contribution of natural fractures to the permeability and skin of any well, whether these fractures are clear or are invaded by drilling mud.

Using a Physical Wellbore Model To Study Formation Damage Problems in Well Completions

Abstract This paper describes the design and operation of a high pressure, high temperature wellbore model using either consolidated or unconsolidated core material. It can be configured with up to eight perforated cores representing varied zonal permeability. The model is set up for flow in either the injection or the production direction. It is acid rated and fluids can be pumped at rates to 130 BPD. Gravel-packing is accomplished in the model with either water or polymer carrier fluids. The model is used to perform laboratory evaluations of completion practices and stimulation techniques. We have evaluated the formation damaging potential of commonly used loss circulation materials and the inability to clean up some of these materials in unconsolidated formations. We have used the model to demonstrate the benefits of gravel pre-packing to avoid loss in perforation flow capacity. We have also evaluated diverting agents designed to improve coverage and stimulation of damaged zones.