| Integrated Services |
| Geophysics |
| Geotechnical Surveying |
| Drilling |
| Directional Drilling |
| Logging |
| Drilling & Completion Fluids |
| Technology of Drilling and Completion Fluids |
| Additive of Drilling/Completion Fluid |
| Simulation Software of Drilling Fluid |
| Solid Control and Drilling Waste Management |
| Cementing |
Technology of Drilling and Completion Fluids
COSL aims to provide efficiency, scientific and low cost services for clients, and continuously promote technical innovation of serializable and customized drilling and completion fluid systems which are applicable for a large scope of drilling fields, such as, extended-reach well, HTHP well, deepwater well, etc.
The PEM system is one kind of environment-friendly water-based anti-collapse drilling fluid system. Its main agent PF-JLX has a cloud point effect, which may make the water-based drilling fluid show similar properties of oil-based drilling fluid when the content of PF-JLX is sufficient, thereby the agent has good stabilizing wellbore and lubricity. It has been widely applied in more than 1000 wells in some oilfields such as the Bohai Bay, the East China Sea, the South China Sea, and Dagang Oilfield, Shengli Oilfield, Jidong Oilfield and Tarim Oilfield since 1995. It has high working efficiency and excellent reservoir protection properties. Its characteristics are as follows: 1) strong inhibition; 2) excellent lubricity; 3) strong resistance to contamination; 4) low damage to the reservoir; 5) environment friendly; 6) little impact on logging.
The GREENDRILL system is a fully biodegradable environment-friendly drilling fluid developed for environmentally sensitive areas, which combines nano-scale deformable physical plugging technology and intelligent inner mud cake technology. The system is constructed from a biodegradable treatment agent with very low biotoxicity, with LC50 value more than 60000ppm, BOD5 / COD value close to 1, and biodegradability rate of 100%. It is suitable for offshore and onshore oilfields with high environmental requirements. The system is characterized by 1) low environmental damage, 2) good lubrication performance, 3) strong inhibition to shale, 4) with no fluorescence or interference with logging operations. The system is widely used in Bohai Sea, South China Sea and Middle East.
Oil-in-water emulsion drilling fluid is formed by spreading the oil on a certain quantity of water base serous fluid with emulgator, its internal phases are: such oil phases as diesel, crude oil, all kinds of low-toxicity mineral oils, etc; its external phases are: fresh water or sea water + viscosifier + filtrate reducer + emulsion, etc. Viscosifier and filtrate reducer are necessary materials for configuring drilling fluid, while emulsion is key to stability of water-base oil-emulsion drilling fluid.
PDF-MOM oil-based drilling fluid system is a kind of water-in-oil drilling fluid with high-temperature resistance and strong anti-pollution ability. PDF-MOM can stabilize wellbore by forming a tough and thin film quickly. All the developed additives in this system working together can provide this fluid with excellent rheological property, thermostability, lubricity, tolerance to water, and solid contamination. Drilling in Weizhou Oilfield in South China Sea is challenged by its complicated geological characteristics, such as narrow drilling window, faults and fissures in shale where sloughing and lost circulation occur frequently. And some wellbores are even abandoned as a result of pipe sticking. This drilling fluid system solved these difficulties meeting the harsh demands of drilling operation. For example, the drilling period of Weizhou Oilfield was shortened by 30.22%. By the end of 2016, PDF-MOM has been successfully applied to more than 100 wells in South China Sea and Indonesia and so on.
Synthetic-base drilling fluid system is a kind of water-base oil-emulsion fluid which takes calcium chloride solution as dispersed phase (internal phase), GTL(Gas-To-Liquid) as continuous phase (external phase) and add emulsion, lipophilic colloid, treating agents and weighting materials, characterized with good rheological property, wide applicable scope of temperature and density, strong inhibitive ability, good lubrication and little damage to clay-bearing sandstone reservoir.
Clay-free OBM is a kind of water-base oil-emulsion fluid which takes calcium chloride solution as dispersed phase (internal phase), low-toxicity mineral oil or synthetic base oil as continuous phase (external phase) and add emulsion, wetting agent and weighting materials, etc and use high-molecular compound to substitute organic soil to form a gel structure. Compared with conventional oil-base drilling fluid containing organic oil, clay-free oil-base drilling fluid could quickly form a gel structure, with a better shear thinning character, therefore it is characterized with better suspension and well cleaning.
SEALING TECHNOLOGY OF OIL-BASE DRILLING FLUID
As for the formation with complicated geological structures such as fractured formation, faults and micro-fractures, the oil-based drilling fluid can seal and plug the micro-fractures, fissures and gaps between rigid particles by introducing the plugging and film-foaming technology, which applies ultra-micro plugging agent PF-MONTF for bridging, and multi-softening-point deformable plugging agent PF-MORLF and PF-MOLSF for soft filling, as well as film-forming agent PF-MOSHIELD for film forming, thus strengthen the wellbore. This fast film-forming and plugging technology of oil-based drilling fluid works with efficiency more than 97%. By the end of 2016, this technology has been successfully applied to more than 30 wells of many oilfields in South China Sea Weizhou area, with zero downhole accident rate and operation period shortened by 20-62%.
CUTTING DRYER SYSTEM
Cutting dryer system could minimize discharge of drilling waste, which directly lowers discharge cost and guarantee it meets local regulations on environmental protection, which could not only reduces discharged quantity of dry cutting, but also recover drilling fluid for recycle. It has noticeable effect on oil base and synthetic base drilling fluid, and the oil content of cutting discharged after handle by cutting dryer is generally below 5%, and processing speed could reach 60 ton/hour.
HEM is a high-performance water-based drilling fluid system which is applied in deepwater and complex formations. The technical problems in deepwater such as fluid thickening in low temperature as well as gas hydrate and narrow safety density window could be solved with the HEM. The system includes 3 primary agents: PF-UHIB, PF-UCAP and PF-HLUB. PF-UHIB (Polyamine) inhibits shale hydration and dispersion with the combination of chemical inhibition and physical plugging. The intercalation into the interlayer of clay with monolayer collapses the hydrated clay structure and expels the water molecules. After adsorption, clay surface became more hydrophobic, which prevents the imbibition of water. The PF-UCAP (low molecular weight) not only has a strong coating ability but also can prevent drilling fluid thickening, plugging screen and mud drain in low temperature environment. The Highly effective anti-sludge package lubricant PF-HLUB can prevent drills balled up by changing the wetting property of the drill’s surface. The features of the system are: 1) the rheology is good at low temperature, 2) the ability of inhibiting hydrate is good, 3) the pressure-tolerant and sealing performance are good, 4) the effect of anti-sludge package is good, 5) the damage to reservoir is small.。
The system was successfully applied in 28 deep wells (including 2 ultra-deep wells, 2 deepwater HTHP wells, and 1 deepwater directional well) in South China Sea before May 2017. The deepest operating depth is 1714m, the deepest well depth is 4448m, and the lowest temperature of mud line is 2.6℃. The advantages of the system are: the rheology is stable at low temperature, the abilities of clay expansion inhibition, sand-carrying and lubrication are strong, the tripping work can be taken easily, all wells can be made logging test once successfully, all holes are near-gauge, and no underground complicated conditions occurred.
FLAT-PRO synthetic-based drilling fluid system is a kind of stable water-in-oil emulsion using environment-friendly and low-viscosity gas oil as continuous phase (external phase). With its flat rheology, this system maintains a constant shearing force in the temperature range of 4~140oC and low ECD. It also develops characteristics including a broad temperature and density range, excellent low-temperature rheological property, strong inhibition, good lubricity, low-toxicity, and least formation damage, and so on. Unlike the traditional synthetic-based drilling fluid, FLAT-PRO drilling fluid system overcomes the technical difficulties such as strong impact of temperature and pressure on rheology, thickening at low temperature, big changes of ECD, start-up pump pressure and excited pump pressure, and possible leakage, etc. Thus, this system is suitable for deep-water and ultra-deep-water oilfield drilling operation. And it created the fastest drilling record of offshore deepwater well construction in Lingshui Oilfield.
DEEPWATER HYDRATE CONTROL TECHNOLOGY
Hydrate control technology can avoid the formation of hydrate. It adds thermodynamic inhibitor into the system to change thermodynamic equilibrium conditions between water and gas molecules, which results in the change of chemical potential of aqueous solution or hydrate, making hydrate dissociation curve move to the side with lower temperature or higher pressure. With this technology, effective control over gas hydrate under various temperature and pressure during the drilling operation can be achieved. The dosage of the inhibitor is determined by both analog computation and indoor instrument evaluation, which can quickly forecast the hydrate formation conditions in wellbore fluid, predict the formation of hydrate in accordance with actual temperature and pressure, optimize the dosage of the inhibitor, and calculate the injection depth of hydrate inhibitor during operation, so as to ensure that the hydrate shall not be formed during static operation such as typhoon avoidance and wireline logging etc.
HIGH SPEED MIXED SYSTEM FOR DYNAMIC KILL DRILLING
Dynamic Kill Drilling applies high-speed slurry system to mix weighted drilling fluid with sea water or salt water in a certain proportion to get drilling fluid of different densities, which will be pumped into the wellbore to prevent shallow geological disasters. During the process of drilling, input work orders and immediately pump the high-density drilling fluid in a large capacity once abnormal high pressure is detected downhole, so as to weight the drilling fluid while operating. This technology has the characteristics of: auto-controllable density, auto slurry-mixing, pumping drilling fluid continuously in a large capacity, etc.
PDF-THERM is a polymer-sulfonate organic salt water-based drilling fluid system with good thermal stability, mainly composed of high-temperature resistant sulfonated material and high-temperature resistant polymer, which benefits the ROP improvement and the borehole stability by retaining the advantage of polymer drilling fluid, improving the mud cake's quality and rheological behavior under HTHP and remedying those inhibition weaknesses of high-temperature resistant drilling fluid system. It applies to those wells with a temperature range of 120℃-220℃ (248℉-428℉). It provides good thermal stability, sand-carrying performance and contamination toleration with little varieties of additives, low HTHP water loss and high plugging capacity, and low reservoir damage. PDF-THERM has been widely used in waters around China and Indonesia. Currently, it is stable to 204℃ (400℉) BHST, with densities reach to 2.32g/cm3 in actual operation.
HT OBM system is a set of high-temperature and high-pressure oil-base drilling fluid system on the basis of requirements of markets, so as to reduce risks of such complex operation as HTHP.
MUD COOLER SYSTEM
In high-temperature and high-pressure drilling operation, it is very important to control the mud’s temperature, lowering the mud’s temperature could reduce well control risks in HTHP drilling operation, guarantee normal working of drilling tool in the well and improving staff’s working environment, etc, so as to improve operation safety and lower operation cost. The mud cooling system provided by COSL could effectively lower and control the mud’s temperature and provide a safe, highly-efficient and cost-saving top-quality service to the operators.
The measures of Prevention and Control of Lost Circulation for WBM mainly covers
Oil-base leakage-proof technology, which mainly utilizes oil soluble material to seal pore throat and microfracture of formation, is composed by the technologies of:
This loss control technology is mainly used in the high-temperature environment, its product shall resist temperature to more than 180℃. The products are: DF-BLN-HT and DF-HTLOCK:
HIBDRILL is a kind of compound salt drilling fluid system with low activity and strong inhibition, which regulates the activity of the drilling fluid with the compound salt and effectively prevents the dissolution of the salt in the strata and the intrusion of the calcium and magnesium ions. Besides, it has excellent rheological properties, excellent inhibition to shale hydration and keeps the hole stable. The characteristics of the system are as follows:
HIBDRILL is a kind of compound salt drilling fluid system with low activity and strong inhibition, which regulates the activity of the drilling fluid with the compound salt and effectively prevents the dissolution of the salt in the strata and the intrusion of the calcium and magnesium ions. Besides, it has excellent rheological properties, excellent inhibition to shale hydration and keeps the hole stable. The characteristics of the system are as follows:
AQUA-MAX is a high-performance water-based drilling fluid whose development is based on the theory of “Activity Balance” and “Osmotic Pressure” with the application of unique physical and chemical plugging technology. AQUA-MAX drilling fluid system primarily consists of shale inhibitor, physical/chemical plugging agent and high-performance temperature-resistant lubricant. For the stability of the borehole, this system has the following unique features.
Physical plugging agent is ultra-fine deformable polymer particle (diameter: ~ 0.2 µm), which can effectively plug the micro-fractures and pores of shale and form a physically block belt to mitigate the invasion speed of the drilling fluid filtrate.
Chemical plugging agent and shale substrate can combine together to form a semi-permeable membrane in the shale surface which can further reduce the shale’s penetration rate, improve the shale’s semi-permeable membrane efficiency and prevent the pressure being transmitted to the formation.
Therefore, the stabilization time of borehole can be significantly extended. The comprehensive effect of AQUA-MAX drilling fluid system on shale is the closest to that of oil-based drilling fluid. AQUA-MAX drilling fluid system has been successfully applied in the South China Sea West, the Bohai Sea and Iraqi Missan Oilfield etc., and successfully solved tremendous problems, such as the instability and micro-leakage of the horizontal wells’ borehole under the salt layer of Iraqi Missan Oilfield.
The PRD system is a kind of solid free weak gel drilling fluids system with good shear thinning properties. With its unique rheological property, the drilling cuttings can be effectively suspended and carried, which prevents the formation of the cuttings bed, neither in extend-reach section nor in the horizontal section and effectively controls the invasion depth of the solid or liquid phase to the reservoir.
The PRD system has functions of both the drilling fluid and the completion fluid, with the excellent adaptability to the environment. It has characteristics of temperature resistance, salt tolerance and shearing resistance. In addition, it is also endowed with excellent suspension property, lubricity and shale inhibition. The filter cake formed is very thin, and it can be easily removed through gel breaking after open hole well completion, which does little damage to the reservoir. It is applicable in the drilling of the horizontal section of the horizontal well. It has been widely used since 2000 in oversea oilfields as well as some sea areas such as Bohai Sea and South China Sea. At present, the system has been applied in more than 1000 wells, representing remarkable effects.
The EZFLOW drilling system is one kind of weak gel drilling fluid for reservoir, with unique rheological properties and excellent performance of reservoir protection. Its plugging and wellbore strengthening capacity has been enhanced through effective plugging. Also the degradability of the treatment chemicals in this system has been improved, which avoids the gel breaking step and simplifies the procedures of the system. The system boasts the characteristics such as wide plugging range and strong wellbore strengthening capacity. Its long molecular chain materials twine around each other on the surface of the rigid plugging material, which works together with the compressible materials to avoid the mutual adhesion of the filter cakes and keep them dispersed. When the positive pressure is removed, the formed thin filter cakes expand and become porous immediately, by which the flowing channel can be recovered and the liquid in the well hole can be discharged quickly with extremely low flowback pressure. At the same time, the system effectively prevents the reservoir from being polluted by the drilling fluids which can be removed with very small pressure drop after completion. It effectively prevents the blockage caused by the conventional drilling fluids in the reservoir, the screen pipes and the gravel bed. Due to its excellent storage and protection effect which results in large output in the production, this system has been widely applied in the Bohai Sea, the South China Sea, and the East China Sea, etc.
HTFLOW, which is a high-temperature drill-in fluid system, could meet high-temperature, high-pressure and high-acid gas operation at the same time. In successful operation of BD project in Indonesia, its operation temperature reaches 160℃, and density reaches 2.0 g/cm3, the reservoir drill-in operation of four wells is smoothly completed and finding production output exceeds ODP production allocation.
HIB FLOW system, which is a water-base reservoir drill-in fluid system of strong inhibition and easy flowback, by means of synergic effect of sale and amine inhibitors, restrains clay hydration inflation and water blocking injury, considerably reduces the stratum’s pore pressure propagation through semi-permeable membrane, stops invasion of solid-liquid phase of sensibility stratum by nanometer sealing technology so as to stabilize shaft lining, it is applicable to drilling of large displacement of reservoir section of large set of shale and sandstone reservoir of argillaceous siltstone and drilling of reservoir of horizontal well section. Since the beginning of 2015, the system has been applied on site at such blocks as BZ25-1 of Bohai, WZ11-4N and LD15-1 in the west of the South China Sea, with a good effect.
Solid-free clean saline water system could be configured with sea water or fresh water, common salt covering: sodium chloride, potassium chloride, calcium chloride, sodium formate, potassium formate, cesium formate, etc, sodium bromide, sodium bromide, calcium bromide, zinc bromide, and mixed salt WT series, etc. In selection of solid-free clean saline water system, besides suitable density, it shall meet such requirements as temperature under the shaft, crystallization point, stratum compatibility and corrosion prevention, etc, and at the same time consider economical efficiency of clean saline water system.
HTAFLOW is a combination of completion fluid and picking solution. Reaction between hydrogen ions released from organic acid and acid soluble materials in reservoir can prevent secondary precipitation of multivalent ions. The reservoir formation can be reconstructed and the acidic completion fluid system of oil and gas flow channel can be improved to a certain extent. This system develops characteristics with excellent consistency, low corrosion rate and good compatibility with various working fluids and formation water. The system has been widely used in offshore oilfield in China since 1998. Up to 2016, the system has been used in more than 1500 wells, with the output increased by an average of nearly 20%.
HTAFLOW is a combination of completion fluid and picking solution. Reaction between hydrogen ions released from organic acid and acid soluble materials in reservoir can prevent secondary precipitation of multivalent ions. The reservoir formation can be reconstructed and the acidic completion fluid system of oil and gas flow channel can be improved to a certain extent. This system develops characteristics with excellent consistency, low corrosion rate and good compatibility with various working fluids and formation water. The system has been widely used in offshore oilfield in China since 1998. Up to 2016, the system has been used in more than 1500 wells, with the output increased by an average of nearly 20%.
HydFLOW system, which is a test liquid system whose main elements are low-heat-conduction base solution and mating corrosion inhibitor, could be used as thermal insulation test liquid or thermal insulation sealing packer fluid in deepwater well and extra deep well whose bottom hole temperature is ≤180℃ and proportion hot higher than 1.7g/cm3, with lower heat conductivity coefficient, good thermal insulation effect, anti-corrosion performance and inhibition performance of gas hydrate.
