Impact of Multi-Branched Ionic Liquid on Shale Swelling and Hydration for High Temperature Drilling Applications

Shale swelling and hydration during the drilling operation have adverse effects on the stability of a wellbore. Hydrophilic interactions of shale results in swelling and disintegration of the shale formation. This paper discusses wettability changes and hydration characteristics of shale to improve the wellbore stability. The use of multibranched ionic liquid as drilling fluid for high temperature applications was investigated. The novel multibranched ionic liquid (Trihexyltetradecyl phosphonium bis (2,4,4-trimethyl pentyl) phosphinate, denoted as Tpb-P) water-based drilling fluid was prepared by mixing different concentrations of ionic liquid and other additives such as filtration controller, rheological modifier, and pH controller. The wettability of bentonite powder was determined using a contact angle in the presence of various concentrations of ionic liquids. Several other experimental techniques, such as linear swelling, hot rolling recovery, and bentonite swell index, were used to examine the inhibition performance of ionic liquid. The rheology and filtration properties of ionic liquid-based drilling fluid were also examined. Various concentrations of multibranched ionic liquid were used to formulate the drilling fluids ranging from (0.1 to 0.5 wt.%), and their performances were compared with the base drilling fluid prepared without ionic liquid. The hydrophobicity of the shale surface was determined by measuring the contact angle, and results showed that drilling fluid having 0.1 wt.% concentration of ionic liquid has a maximum contact angle indicating the highly hydrophobic shale surface. The hot rolling shale recovery experiment was conducted at 150°F, and it was observed that adding ionic liquid improved the shale recovery (24.4%) compared to the base fluid recovery (12.8%). The linear swelling was evaluated over the time of 24 hours, and the least swelling of bentonite was noticed with 0.1 wt.% ionic liquid (98.1%) compared to linear swelling in deionized water (125%). The results suggested that the ionic liquid in the drilling fluid chemically interacted with the clay surface and reduced the hydrophilicity of clay, which restricts the exchange of water onto the clay surface.

Experimental study of Zubair shale stability of east Baghdad oil field using different additives in water based mud

Shale formation is represented as one of the challenge formations during drilling wells because it is a strong potential for wellbore instability. Zubair formation in Iraqi oil fields (East Baghdad) is located at a depth from 3044.3 to 3444 m. It is considered as one of the most problematic formations through drilling wells in East Baghdad. Most problems of Zubair shale are swelling, sloughing, caving, cementing problem and casing landing problem caused by the interaction of drilling fluid with the formation. An attempt to solve the cause of these problems has been adapted in this paper by enhancing the shale stability through adding additives to the drilling fluid. The study includes experiments by using two types of drilling fluids, API and polymer type, with five types of additives (KCl, NaCl, CaCl2, Na2SiO3 and Flodrill PAM 1040) in different concentrations (0.5, 1, 5 and 10) wt% and different immersion period (1, 24 and 72 h) hours. The effect of drilling fluids and additive salts on shale has been studied by using different techniques: (XRD, XRF, reflected and transmitted microscope) as well shale recovery. The results show that adding 10 wt% of Na2SiO3 to API drilling fluid results in a high percentage of shale recovery (78.22%), while the maximum shale recovery was (80.57%) in polymer drilling fluid type gained by adding 10 wt% of Na2SiO3.

Analyzing Effects of Multi-Wall Carbon Nanotubes (MWCNT) & Polyethylene Glycol (PEG) on Performance of Water Base Mud (WBM) in Shale Formation

Background: Due to importance and unique properties of Multi-Wall Carbon Nanotube(s) (MWCNT), in the present study, effectiveness of these materials in Water Base Mud (WBM) is evaluated. Objective: The impacts of mud additives, local water and the addition of phases of bentonite and surfactants on the rheological properties, water loss and stability of water base mud in the absence of Multi-Wall Carbon Nanotube have been experimentally investigated. Materials and Methods: Then, the same experiment performed in the presence of Multi-Wall Carbon Nanotube to determine the efficiency and impact of Nanoparticles (NPs) on the properties of water base mud. The results have shown that additives, local water, Multi-Wall Carbon Nanotube dimensions, addition phase of bentonite and surfactants have influenced the rheological properties of the water base mud. Results: When Multi-Wall Carbon Nanotubes and polyethylene glycol alone or together are added, the performance terms of rheological properties decrease as by the subsequent order CNT; CNT + PEG; PEG. Multi-Wall Carbon Nanotube improves shale integrity and increases shale recovery. Conclusion: In general, the presence of Multi-Wall Carbon Nanotube increases the efficiency of polymers and rheological properties of the water base mud and eventually the shale stability is achieved.

OPEC deal would encourage US shale producer rally

Significance The US shale industry has emerged from the worst of the crude price downturn battered, but also leaner and more efficient. Many shale producers are eager to return to growth, buoyed by a more stable oil price at around 50 dollars per barrel. However, oil prices need to rise somewhat higher still to give enough of a jolt to the industry to see US oil production return to meaningful growth. Impacts Oilfield service companies, especially fracking specialists, stand to gain if shale drilling activity picks up on the back of higher prices. The Permian shale in West Texas will lead any US shale recovery, due to its lower costs and large reserves, boosting the region’s economy. The Bakken and Eagle Ford shale plays will follow the Permian shale in a price recovery. Prices above 70 dollars per barrel would probably be required for investment to return to Gulf of Mexico deepwater projects.

Preparation and Performance of Wax Emulsionusing in Drilling Fluid

An O/W type paraffin wax emulsions was prepared using Tweenand Span emulsifiers, and liquid paraffin. The influences of temperature, HLB and surfactants concentration in particle size of paraffin wax emulsions were studied, as were the stability of paraffin wax emulsions. The application performances in drilling fluid of paraffin wax emulsions were researched with respect to artificial core line swelling and shale recovery. Results showed that the best conditions of preparation of emulsified wax: surfactants concentration was 5%, temperature was 50°Cand HLB was 10.1-10.5. It was found that paraffin wax emulsions possess strong inhibition ability for hydration, swelling and dispersing of clay and shale. The inhibition ability of paraffin wax emulsions enhanced with KCl.

Study of Strata Sloughing Mechanism and Anti-Sloughing Measures with Mechanics Properties and Material Properties in Yitong Area

As there are serious wellbore instability problems in Yitong area, studying sloughing mechanism and anti-sloughing measures of the strata is of great importance, which differs significantly from the previous researches. Based on the international state-of-the-art, in this work several points are focused on which include the appearance characteristics of the cores, rock mineral composition and the shale physical and chemical properties. Sloughing mechanism is classified and anti-sloughing measures of the strata in Yitong area are proposed. When testing shale physical and chemical properties, several parameters are mainly tested and analyzed, including cation exchange capacity, specific water absorption, shale recovery rate and shale inflation rate. Five core samples are selected and collated data is reflected in tables in the experiment. It is worth mentioning that a new method of specific water absorption is adopted in the study to explain wellbore instability problems, which are caused by hydration. Limitations and shortcomings have been overcome by specific water absorption instead of total water absorption when evaluating water sensibility. The test shows satisfying and excellent results. After applying the anti-sloughing measures to the strata in Yitong area, sloughing accidents have been alleviated.