The Conversion of Non-Dispersed Polymers into Low-Potassium Anti-Collapse Drilling Fluids

Different drillingfluid systems are designed according to mineral composition,lithology and wellbore stability of different strata.In the present study,the conversion of a non-dispersed polymer drillingfluid into a low potas-sium anti-collapsing drillingfluid is investigated.Since the two drillingfluids belong to completely different types,the key to this conversion is represented by new inhibitors,dispersants and water-loss agents by which a non-dispersed drillingfluid can be turned into a dispersed drillingfluid while ensuring wellbore stability and reason-able rheology(carrying sand—inhibiting cuttings dispersion).In particular,the(QYZ-1)inhibitors and(FSJSS-2)dispersants are used.The former can inhibit the hydration expansion capacity of clay,reduce the dynamic shear force and weaken the viscosity;the latter can improve the sealing effect and reduce thefiltrate loss.The results have shown that after adding a reasonable proportion of these substances(QYZ-1:FSJSS-2)to the non-dispersed polymer drillingfluid,while the apparent viscosity,plastic viscosity,structural viscosity andfluidity index under-went almost negligible changes,the dynamic plastic ratio increased,and thefiltration loss decreased significantly,thereby indicating good compatibility.According to the tests(conducted in the Leijia area),the density was 1.293 g/cm3,and after standing for 24 h,the SF(static settlement factor)was 0.51.Moreover,thefiltration loss was reduced to 4.0 mL,the rolling recovery rate reached 96.92%,with excellent plugging and anti-collapse performances.

Optimization of Anti-Collapse Drilling Fluid Systems with High Potassium Content

The ash mudstone in some oil formations is highly water-sensitive.The oil formation is fractured,and the risk of well leakage and collapse is not negligible.This study presents a countermeasure for well collapse prevention,based on a“force-chemistry synergistic balance”approach and the utilization of environmentally friendly and efficient hydration inhibitors.The relevance of this approach is demonstrated considering a drilling fluid system with the high potassium content.The analysis shows that the system can maintain good rheological properties,filtration loss and suspension stability even after aging at 130℃ for 16 h.The primary roll recovery of rock chips is better than 98%.The secondary rolling recovery rate is 89%.The rapid water loss is close to zero.The effects of carrying rock,sand,hydration inhibition and dispersion of drill chips are all noticeable.

Study on a Polyamine-Based Anti-Collapse Drilling Fluid System

In complex strata, oil-based drilling fluid is the preferred drilling fluid system, but its preparation cost is high, and there are hidden safety risks. Therefore, the new progress of high-performance anti-collapse water-based drilling fluid at home and abroad is analyzed. It is difficult to prevent and control the well collapse. Once the well wall instability problem occurs, it will often bring huge economic losses to the enterprises, and the underground safety accidents will occur. In order to ensure the stability of the well wall and improve the downhole safety, the key treatment agent of water-based collapse drilling fluid is selected, the anti-collapse drilling fluid system is formulated, the evaluation method of drilling fluid prevention performance is established, and a set of water-based drilling fluid system suitable for easy to collapse strata in China is selected to ensure the downhole safety. The development trend of high performance anti-collapse water-based drilling fluid is expected to provide a reference for the research of high performance anti-collapse water-based drilling fluid system and key treatment agent.

Preparation of fluidized catalytic cracking slurry oil-in-water emulsion as anti-collapse agent for drilling fluids

Fluidized catalytic cracking slurry oil-in-water emulsion(FCCSE)was prepared by using interfacial complexes generation method that was simple and versatile.The critical factors influencing the sample preparation process were optimized,for instance,the optimum value of the mixed hydrophile-lipophile balance of compound emulsifier was 11.36,the content of compound emulsifier was 4 wt%,the emulsification temperature was 75
C,the agitation speed was 200 rpm,and the emulsification time was 30e45 min.The performance as a drilling fluid additive was also investigated with respect to rheological properties,filtration loss and inhibition of FCCSE.Experimental results showed that FCCSE was favorable to inhibiting clay expansion and dispersion and reducing fluid loss.Furthermore,it had good compatibility with other additives and did not affect the rheological properties of drilling fluids.FCCSE exhibited better performance than the available emulsified asphalt.It has a promising application as anti-collapse agent in petroleum and natural gas drilling.

Four kinds of antibody positive paraneoplastic limbic encephalitis: A rare case report

BACKGROUND It is not uncommon to develop autoimmune encephalitis and paraneoplastic neurological syndromes(PNS).4 kinds of antibody-positive autoimmune paraneoplastic limbic encephalitis(PLE)have not been reported.CASE SUMMARY PNS are distant effects of cancer on the nervous system,rather than syndromes in which cancer directly invades and metastasizes to the nerves and/or muscle tissues.If the limbic lobe system of the brain is involved,this will result in PLE.The detection of patients with PNS is challenging since tumors that cause paraneoplastic neurologic disorders are often asymptomatic,obscure,and thus easily misdiagnosed or missed.Currently,single-or double-antibody-positive paraneoplastic marginal encephalitis has been reported.However,no cases of three or more-antibody-positive cases have been reported.Here,we report a case of PLE that is anti-collapsing response-mediator protein-5,anti-neuronal nuclear antibody-type 1,anti-aminobutyric acid B receptor,and anti-glutamate deglutase positive,and address relevant literature to improve our understanding of the disease.CONCLUSION This article reports on the management of a case of PLE with four positive antibodies,a review of the literature,in order to raise awareness among clinicians.