Palm fronds collected in Khartoum State were washed, air-dried, ground, and soaked in water for approximately 20 min. The available experimental record states that the fibers were cooked repeatedly in 500 mL of 1 M NaOH (approximately 4% w/v) at 80˚C for 4 h and washed with distilled water. Bleaching was then repeated four times for 4 h at 80˚C using a commercial sodium hypochlorite solution reported as 1.7% NaOCl, with 2.5% NaOH and 75 mL acetic acid, followed by washing until hypochlorite odor was no longer detected. However, the record does not report the dry palm-frond mass treated in each batch; consequently, the solid-to-liquid ratio cannot be reconstructed. It also does not report measured pH values or a controlled pH trajectory during cooking or bleaching.

For carboxymethylation, 2 g of isolated cellulose was suspended in 40 mL of an alcohol medium, and 10 mL of 30% aqueous NaOH was added dropwise over 30 min before 1 h of mixing at room temperature. The archived method lists isopropanol, n-butanol, ethanol, and methanol as candidate alcohols but does not identify which single solvent or mixture, its purity, or its composition was used for the reported batch. Likewise, 6.00 g monochloroacetic acid was dissolved in 10 mL of a solvent listed as isopropanol or ethanol, without identifying the selected solvent or purity. The reaction proceeded at 55˚C for 4 h, was neutralized with 90% acetic acid, filtered, washed five times with 70% ethanol, and dried at 60˚C. Purification comprised dispersion in 60 mL of 95% ethanol, addition of 10 mL of 2 M nitric acid, heating to boiling for 5 min, further agitation for 15 min, washing with 95% ethanol and hot 80% ethanol, methanol washing, and drying at 105˚C for 3 h. These solvent ambiguities are now reported explicitly because they prevent exact reproduction and should be resolved in a controlled repeat study.

Cellulose yield, final CMC yield, moisture, ash, chloride, and active-polymer content were not measured in the archived work. Degree of substitution and functional-group confirmation by FTIR, NMR, or titration were also not available. Accordingly, the material is described operationally as a palm-frond-derived CMC candidate, and XRD similarity is not treated as proof of etherification, substitution level, or substitution uniformity.

A commercial high-viscosity CMC served as the benchmark. Three bentonites (A, B, and C) were screened using 22.5 g of clay in 350 mL of deionized water. Each clay suspension was mixed for 5 min and tested without a reported 16-h prehydration/aging period. Bentonite B was selected because it combined the lowest PV (7 cP) with a moderate YP (11 lb/100ft²), although its filtrate (18.8 mL) was the highest of the three. The full screening dataset is provided in Table 1, because fresh and aged clay dispersions can give materially different rheology and filtration. All subsequent concentration results therefore apply to freshly prepared, non-aged bentonite B under the recorded protocol.

Table 1. Screening data for the three candidate bentonites (single measurements; 22.5 g/350mL).

Powder X-ray diffraction was conducted with a Philips X’Pert diffractometer using Cu Kα radiation (λ = 1.5406 Å). The patterns were used only for qualitative comparison. The phase search for the synthesized product did not converge under Rietveld refinement and showed substantial residual inorganic peaks. XRD, therefore, neither confirms carboxymethyl ether formation nor quantifies the degree of substitution, substitution uniformity, active content, or polymer purity. These properties remain unmeasured and are required for definitive identification and structure-performance interpretation.

Polymer-containing fluids were mixed for 20 min and then evaluated using a ZNN-D6 six-speed rotational viscometer. The mixer model was recorded, but its rotational speed was not; this is a reproducibility limitation. No additional hydration period or 16-h aging step was documented after polymer addition. Apparent viscosity (AV), plastic viscosity (PV), and yield point (YP) were calculated as AV = θ600/2, PV = θ600 − θ300, and YP = θ300 − PV. Filtration was measured for 30 min at 0.69 MPa. Commercial CMC additions were 0.1 - 2.0 g (0.44% - 8.89% of bentonite mass), whereas palm-frond material additions were 1.1 - 5.6 g (5% - 25%). For the temperature series, samples were conditioned for 30 min at 25˚C, 50˚C, 75˚C, or 90˚C. The archived record does not establish whether evaporation was controlled, whether the viscometer cup was maintained at the stated temperature, or whether dial readings were taken hot or after cooling. Consequently, the temperature data are reported as screening observations, not intrinsic thermal-stability measurements. Short static conditioning is not equivalent to sealed 16-h hot rolling.

Grade screening was operational rather than a complete API 13A qualification. The commercial material was screened at 2.2 g in 350 mL deionized water after 20 min mixing and gave θ600 = 37. The palm-frond material was screened separately at 10.5 g in 350 mL deionized water after 20 min mixing and gave θ600 = 30. Because the concentrations were non-equivalent and the complete prescribed API solution matrix was not run, these readings support only the descriptive labels “higher-viscosity commercial material” and “lower-viscosity palm-frond material” under the study conditions.

Every reported condition represents one measurement (n = 1). No laboratory duplicates, standard deviations, confidence intervals, or p-values are available. Error bars cannot be calculated retrospectively. Differences close to normal test repeatability, including 5.8 versus 6.0 mL filtrate, are therefore not interpreted as meaningful differences (Table 2).

Table 2. Experimental design and measured responses.

Three 350-mL KCl-polymer fluids were compared: a reference containing 4 g PAC-LV; the same formulation without PAC-LV; and the PAC-free formulation treated with 4 g palm-frond CMC. Each also contained 0.5 g caustic soda, 0.5 g soda ash, 0.5 g xanthan-type viscosifier, 2 g fluid-loss additive, and 15 g KCl. This sequence isolated the incremental contribution of the synthesized CMC, although it was a screening comparison rather than a statistically replicated replacement study.

Under the operational screening described in Section 2.2, the commercial material gave θ600 = 37 at 2.2 g/350mL, whereas the palm-frond material gave θ600 = 30 at 10.5 g/350mL. These non-equivalent concentrations do not support a formal, reproducible API grade assignment. They indicate only that the palm-frond product had substantially lower viscosity-building efficiency per unit mass in this dataset. Depending on the selected response target, approximately three to ten times more palm-frond material was required than commercial CMC.

Both products reduced fluid loss monotonically at 25˚C, but their rheological signatures were distinct (Figure 1). Commercial CMC strongly increased θ600 and YP: at 8.89%, θ600 reached 197, and YP reached 141 lb/100ft². Such values indicate severe over-treatment for many circulating systems, despite the favorable filtrate of 8.8 mL. In contrast, palm-frond CMC increased θ600 gradually from 25 to 38 and PV from 7 to 15 cP over 0% - 25%, while YP decreased from 11 to 8 lb/100ft² and then remained nearly constant. This combination suggests that the synthesized grade primarily increased continuous-phase viscosity and filter-cake quality without generating the strong interparticle structure observed for the commercial high-viscosity grade.

Figure 1. Concentration response at 25˚C. Percentages are relative to bentonite mass. Each point is a single measurement (n = 1); lines guide the eye, and no error bars are available.

At the highest tested dosage, palm-frond CMC reduced filtrate from 19 to 10 mL/30min, a 47.4% decrease. A 20% dosage delivered 10.8 mL with PV of 14 cP and YP of 8 lb/100ft². These values may be useful where filtration control is needed without a large increase in annular yield stress, but the relatively low YP also means that hole-cleaning performance cannot be assumed. The required concentration should therefore be selected jointly from hydraulic, cuttings-transport, and filtration constraints rather than from fluid loss alone (Table 3).

Table 3. Selected 25˚C performance points.

Figure 2.Short-duration temperature-screening results at fixed, non-equivalent dosages: commercial CMC at 6.67% and palm-frond material at 20% of bentonite mass. Each point is a single measurement (n = 1); no error bars are available, and the protocol was not equivalent to 16-h hot rolling.

At the selected dosages, the single filtrate readings decreased between 25˚C and 50˚C, reaching 6.0 mL for commercial CMC and 5.8 mL for the palm-frond material. The 0.2-mL separation is not evidence of superior or equivalent performance because repeatability was not measured, and no statistical comparison is possible. Above 50˚C, the isolated filtrate readings increased to 9.0 and 8.2 mL at 90˚C. Rheological responses were nonmonotonic: the palm-frond system increased from θ600 = 36 at 25˚C to 72 at 75˚C and then decreased to 62 at 90˚C. This unexpected increase may reflect continued hydration, evaporation, measurement-temperature differences, or experimental variation; the archived protocol cannot distinguish among these explanations (Figure 2).

The temperature series demonstrates only short-duration screening behavior. Evaporation control and the temperature at which dial readings were taken were not documented, and the samples were not subjected to sealed 16-h hot rolling followed by measurement at a common temperature. The results, therefore, do not establish thermal stability, equivalence, or superiority. Replicated, sealed aging with controlled cooling and mass-balance checks is required before temperature-dependent claims can be made.

Figure 3.KCl-polymer rheology screen. θ600 and θ300 are dial readings; PV is in cP, and YP is in lb/100 ft². Values are single measurements (n = 1).

Figure 4. KCl-polymer filtration screen. Filtrate volume is shown separately to avoid combining unlike units on one axis. Values are single measurements (n = 1).

Removing PAC-LV from the KCl-polymer reference reduced θ600 from 36 to 10, PV from 12 to 4 cP, and YP from 12 to 2 lb/100ft², while the single filtrate reading increased from 10.2 to 17.2 mL (Figure 3 and Figure 4). Addition of 4 g palm-frond material raised θ600 to 14 and YP to 6 lb/100ft² and produced a filtrate reading of 15.6 mL. These isolated values show directional recovery relative to the PAC-free formulation, but they are not evidence of a statistically significant 9.3% filtration improvement or of replacement equivalence. The formulation was an exploratory compatibility screen.

Foaming and incomplete dissolution were observed during mixing. Both can bias rheology and filtration by entraining air and reducing the effective dissolved-polymer concentration. Process optimization should therefore address particle size, salt removal, drying history, dissolution sequence, and defoamer compatibility. The strong NaCl signal reported by qualitative phase matching is consistent with incomplete inorganic removal, although XRD alone cannot determine polymer purity. Conductometric ash, chloride, moisture, degree of substitution, molecular-mass distribution, and FTIR/NMR characterization are required to connect synthesis chemistry with drilling performance (Table 4).

Table 4.KCl-polymer formulation screening results.

The most defensible application for the current product is as a low-viscosity filtration-control additive in fresh to moderately saline water-based fluids where excessive rheology is undesirable. The palm-frond route converts an agricultural residue into a technically active polymer and could reduce exposure to imported specialty chemicals. However, cost advantage cannot be inferred from customs values alone. A credible economic assessment must include cellulose yield, reagent recovery, solvent recycle, water and energy use, neutralization, drying, waste treatment, quality-control losses, packaging, transport, and the higher field dosage required relative to commercial CMC or PAC.

Several limitations define the boundary of the conclusions. All conditions were measured once (n = 1), so variability and statistical significance are unknown. The two CMC materials were tested at different concentrations, preventing intrinsic efficiency or equivalence claims. Bentonite was tested without documented 16-h prehydration, mixer speed was unrecorded, and the temperature protocol did not document evaporation control or measurement temperature, and was not equivalent to hot rolling. Cellulose yield, CMC yield, active content, moisture, residual salt, degree of substitution, and functional-group confirmation were not measured. Qualitative XRD cannot establish etherification or substitution uniformity. Finally, the KCl formulation was a single screen without contamination, lubricity, shale-recovery, sag, or return-permeability testing. The study should therefore be read as feasibility screening only.

Future work should repeat the key conditions with at least three independent preparations, report mean ± standard deviation and confidence intervals, and apply statistical tests selected before data collection. Base bentonite should be prehydrated for a controlled period, and mixer speed, sequence, and temperature should be recorded. Thermal testing should use sealed 16-h hot rolling, controlled cooling to a common reporting temperature, evaporation/mass-balance checks, and replicate API/HPHT filtration. Synthesis records should identify the exact alcohol and monochloroacetic-acid solvent, their purities and compositions, solid-to-liquid ratio, pH, and cycle count. Cellulose and CMC yields, degree of substitution, FTIR/NMR evidence, molecular-mass distribution, moisture, ash, chloride, and active content should be reported before benchmarking against API 13A and commercial CMC-LV/PAC-LV.