Case Study of Identifying and Minimizing Formation Damage in Tight Reservoirs Caused by Drilling Fluids in Abu Dhabi Onshore Operation Using Compatibility Coreflood Studies

A study was carried out to examine formation damage mechanisms caused by drilling fluids in tight reservoirs in several onshore oil fields in Abu Dhabi. Three phases of compatibility corefloods were carried out to identify potential to improve hydrocarbon recovery and examine reformulated/alternate drilling muds and treatment fluids. Interpretation was aided by novel Nano-CT quantifications and visualisations. The first phase examined the current drilling muds and showed inconsistent filtrate loss control alongside high levels of permeability alteration. These alterations were caused by retention of drilling mud constituents in the near-wellbore and incomplete clean-up of drilling mud-cakes. Based upon these results, reformulated and alternate drilling muds were examined in Phase 2, and there was a positive impact upon both filtrate loss and permeability, although the Nano-CT quantifications and visualisations showed that drilling mud constituents were still having an impact upon permeability. Candidate treatment fluids were examined in Phase 3, with all having a positive impact and the best performance coming from 15% HCl and an enzyme-based treatment. The interpretative tools showed that these treatments had removed drilling mud-cakes, created wormholes, and bypassed the areas where constituents were retained. The compatibility corefloods on tight reservoir core, alongside high-resolution quantifications and visualisations, therefore identified damaging mechanisms, helped identify potential to improve hydrocarbon recovery, and identify treatment fluid options which could be used in the fields.

Development and Application of a Novel Green Water-Based Drilling Fluid

In response to the technical and environmental protection requirements of water-based drilling fluids, this study independently developed a series of green supporting treatment agents for water-based drilling fluids such as the green loss reducer HB-1, green inhibitor HB-2, and green lubricant HB-3, etc., and proposed a green water-based drilling fluid system (HBDF) with good comprehensive performance. The proposed system has a heat resistance of 150°C, a HTHP (high temperature and high pressure) filtrate loss of 12 mL, a biological toxicity EC50 value greater than 105 mg/L, and a biodegradability BOD5/CODCr value of 16.2%. Now the developed HBDF system has been applied in more than 10 wells in SL oilfield, and the field application results show that the proposed HBDF system has stable rheological and filtrate loss performance, good anti-pollution ability, and easy and simple maintenance operations; after drilling, the biological toxicity of the drilling fluids can meet the environmental protection requirements, which has provided a technical reference for the research of green drilling fluids and the green development of SL Oilfield.

Effect of Iron Oxide Nanoparticles on the Properties of Water-Based Drilling Fluids

In recent years, several studies have indicated the impact of nanoparticles (NPs) on various properties (such as viscosity and fluid loss) of conventional drilling fluids. Our previous study with commercial iron oxide NPs indicated the potential of using NPs to improve the properties of a laboratory bentonite-based drilling fluid without barite. In the present work, iron oxide NPs have been synthesized using the co-precipitation method. The effect of these hydrophilic NPs has been evaluated in bentonite and KCl-based drilling fluids. Rheological properties at different temperatures, viscoelastic properties, lubricity, and filtrate loss were measured to study the effect of NPs on the base fluid. Also, elemental analysis of the filtrate and microscale analysis of the filter cake was performed. Results for bentonite-based fluid showed that 0.019 wt% (0.1 g) of NPs reduced the coefficient of friction by 47%, and 0.0095 wt% (0.05 g) of NPs reduced the fluid loss by 20%. Moreover, for KCl-based fluids, 0.019 wt% (0.1 g) of additive reduced the coefficient of friction by 45%, while higher concentration of 0.038 wt% (0.2 g) of NPs shows 14% reduction in the filtrate loss. Microscale analysis shows that presence of NPs in the cake structure produces a more compact and less porous structure. This study indicates that very small concentration of NPs can provide better performance for the drilling fluids. Additionally, results from this work indicate the ability of NPs to fine-tune the properties of drilling fluids.

Effect of Hydrophobic Iron Oxide Nanoparticles on the Properties of Oil-Based Drilling Fluid

Lately, nanoparticles (NPs) have shown the potential to improve the performance of oil well fluids significantly. Several studies have reported the ability of NPs to produce improved properties of both water and oil-based drilling fluids. In this study, hydrophobic iron oxide NPs were synthesized by thermal decomposition of iron pentacarbonyl in an inert atmosphere, and its performance was tested in the oil-based drilling fluid with 90/10 oil-to-water ratio (base fluid). Oil-based drilling fluids treated with nanofluids were formulated by adding 0.5 wt% and 1.0 wt% iron oxide NPs in hexane solution to the base drilling fluid. The base fluid and the nanofluid-treated drilling fluids were evaluated by characterizing their rheological properties at different temperatures, viscoelastic properties, lubricity, filtrate loss, static and dynamic settling, and separation properties. Results showed that 0.5 wt% iron oxide dispersed in hexane reduced the high pressure high temperature (HPHT) filtrate loss by 70%, filter cake thickness by 55%, and the coefficient of friction by 39%. Moreover, the nanofluid based drilling fluid reduced the free oil layer caused by syneresis during aging at high temperature by 16.3% compared to the base fluid. This study has shown that hydrophobic iron oxide NPs have the potential to improve the properties of oil-based drilling fluid.

Effect of Hydrophobic Iron Oxide Nanoparticles on the Properties of Oil Based Drilling Fluid

In recent years, nanoparticles (NPs) have shown the potential to improve the performance of oil well fluids significantly. Several studies have reported the ability of NPs to produce improved properties of both water and oil-based drilling fluids. In this paper, hydrophobic iron oxide NPs were synthesized by thermal decomposition of iron pentacarbonyl in an inert atmosphere, and its performance was tested in the oil-based drilling fluid with 90/10 oil to water ratio (base fluid). Oil-based drilling fluids treated with nanofluids were formulated by adding 0.5 wt. % and 1.0 wt. % iron oxide NPs in hexane solution to the base drilling fluid. The base fluid and the nanofluid treated drilling fluids were evaluated by characterizing their rheological properties at different temperatures, viscoelastic properties, lubricity, filtrate loss, static & dynamic settling, and separation properties. Results showed that 0.5 wt. % iron oxide dispersed in hexane reduced the HPHT filtrate loss by 70%, filter cake thickness by 55%, and the coefficient of friction by 39%. Moreover, the nanofluid based drilling fluid reduced the free oil layer caused by syneresis during aging at high temperature by 16.3% compared to the base fluid. This study has shown that hydrophobic iron oxide NPs have the potential to improve the properties of oil-based drilling fluid.

Nanomaterial-Based Drilling Fluids for Exploitation of Unconventional Reservoirs: A Review

The world’s energy demand is steadily increasing where it has now become difficult for conventional hydrocarbon reservoir to meet levels of demand. Therefore, oil and gas companies are seeking novel ways to exploit and unlock the potential of unconventional resources. These resources include tight gas reservoirs, tight sandstone oil, oil and gas shales reservoirs, and high pressure high temperature (HPHT) wells. Drilling of HPHT wells and shale reservoirs has become more widespread in the global petroleum and natural gas industry. There is a current need to extend robust techniques beyond costly drilling and completion jobs, with the potential for exponential expansion. Drilling fluids and their additives are being customized in order to cater for HPHT well drilling issues. Certain conventional additives, e.g., filtrate loss additives, viscosifier additives, shale inhibitor, and shale stabilizer additives are not suitable in the HPHT environment, where they are consequently inappropriate for shale drilling. A better understanding of the selection of drilling fluids and additives for hydrocarbon water-sensitive reservoirs within HPHT environments can be achieved by identifying the challenges in conventional drilling fluids technology and their replacement with eco-friendly, cheaper, and multi-functional valuable products. In this regard, several laboratory-scale literatures have reported that nanomaterial has improved the properties of drilling fluids in the HPHT environment. This review critically evaluates nanomaterial utilization for improvement of rheological properties, filtrate loss, viscosity, and clay- and shale-inhibition at increasing temperature and pressures during the exploitation of hydrocarbons. The performance and potential of nanomaterials, which influence the nature of drilling fluid and its multi-benefits, is rarely reviewed in technical literature of water-based drilling fluid systems. Moreover, this review presented case studies of two HPHT fields and one HPHT basin, and compared their drilling fluid program for optimum selection of drilling fluid in HPHT environment.

Analisis Rheologi Lumpur Lignosulfonat dengan Penambahan LCM Berbahan Serbuk Gergaji, Batok, dan Sekam Berbagai Temperatur

<p><em>Kehilangan sirkulasi lumpur merupakan kejadian </em>yang sering terjadi dalam proses pemboran. Hilang lumpur yang terjadi bisa saja sebagian dari lumpur pemboran dan bahkan kehilangan lumpur pemboran secara total. Pada percobaan ini kehilangan lumpur pemboran akan diteliti dalam skala laboratorium. Dengan penambahan LCM diharapkan berguna untuk menanggulangi hilangnya lumpur tersebut. Dengan mencoba mengalirkan lumpur pada media berpori yang telah ditentukan, kehilangan lumpur akan dilihat dari seberapa besar lumpur yang hilang dalam skala laboratorium yang dibuat. Kemudian lumpur yang dibuat ditambahkan LCM berupa serbuk gergaji, batok kelapa dan sekam padi dan diteliti seberapa besar pengaruh LCM dalam mengurangi kehilangan lumpur tersebut. Campuran macam LCM lumpur tersebut juga diuji pengaruhnya terhadap beberapa tingkatan temperatur antara lain temperatur 80^oF, 190^oF dan 300^oF, tentunya hal ini dilakukan untuk mendapatkan nilai <em>sealing </em>yang baik pada masing-masing LCM jika berada pada keadaan temperatur yang tinggi yang dikondisikan dengan kondisi sumur sebenarnya. Percobaan ini juga dilakukan untuk mengetahui <em>filtrate loss</em> yang terjadi pada berbagai macam campuran lumpur dengan LCM tersebut. Ketebalan <em>mud cake</em> yang terbentuk dalam pengukuran kehilangan filtrat juga diamati seberapa besar mud cake yang dihasilkan. Dan setelah itu reologi dari masing-masing lumpur tersebut juga diukur untuk menyimpulkan hasilnya. </p><p><em>Loss of mud circulation is an event that often occurs in the drilling process. The loss of mud that occurred could have been partly from drilling mud and even total drilling mud loss. In this experiment, drilling mud losses will be investigated on a laboratory scale. With the addition of LCM, it is hoped that this will be useful to overcome the loss of mud. By trying to flow sludge in a predetermined porous media, sludge loss will be seen from how much sludge is lost on a laboratory scale created. Then the LCM sludge was added in the form of sawdust, coconut shells and rice husks and examined how much influence the LCM had in reducing the sludge loss. The mixture of LCM sludge is also tested for its effect on several temperature levels including 80oF, 190oF and 300oF, of course this is done to get a good sealing value in each LCM if it is in a high temperature condition which is conditioned to actual well conditions. This experiment was also conducted to determine the filtrate loss that occurs in various slurry mixtures with the LCM. The thickness of the mud cake formed in the measurement of filtrate loss was also observed how much the mud cake was produced. And after that the rheology of each mud is also measured to conclude the results.</em></p>