33 results about "Wellbore instability" patented technology

The invention discloses a method for forecasting a weak plane formation collapse pressure equal yield density window. The method sequentially includes the steps: dividing a weak plane formation into a compact section and a crack section according to characteristics of the weak plane formation; testing the strength of a rock body and the strength of a weak plane of a rock by the aid of the triaxial compression test of the rock; inverting stress distribution and pore pressure distribution of surrounding rocks of a compact formation well by the aid of a fluid-solid coupling model, and determining the lower limit of the collapse pressure equal yield density of a compact formation according to Mohr-coulomb failure criteria; analyzing the failure state of the surrounding rocks of the weak plane formation well according to the rock weak plane failure criteria, and determining the lower limit and the upper limit of the collapse pressure equal yield density window of a crack formation; building a weak plane formation collapse pressure equal yield density window calculation model, substituting parameter values into the model and then determining the weak plane formation collapse pressure equal yield density window. The weak plane formation collapse pressure equal yield density window can be forecasted before drilling, so that drilling fluid density is reasonably selected, and wellbore instability is effectively stopped.

The invention relates to low density water-based drilling fluid for drilling into shale. The fluid overcomes the problem of wellbore instability when the water-based drilling fluid is used. The drilling fluid adopts the technical scheme that the drilling fluid comprises the following raw materials: 30-50g bentonite for the drilling fluid, 1.5-2.5g sodium carbonate, 5-10g sodium hydroxide, 15-20g shear strength improving agent SZT, 2-5g zwitterionic polymer coating agent FA367, 10-15g fluid loss agent CG810S-T, 0.2-1g drilling fluid rheological regulator JHRM, 40-60g highlight calcium carbonate C-L501, 10-30g lubricant R-16, 25-35g emulsified paraffin, 40-60g solid polymerization alcohol JHGC for the drilling fluid and 1000g tap water. The tap water, the bentonite for the drilling fluid and soda are added for prehydration for 24h first, the shear strength improving agent SZT is added under the mixing condition at 8000r/min, then the treatment agents are sequentially added under the mixing condition at 500r/min, pH (potential of hydrogen) of a system is regulated to 8.5, and barite is added finally. The drilling fluid system has good rejection capability and blocking performance and is used for drilling of a long horizontal section of a shale bed.

A foam drilling fluid is prepared from, in percentage by mass, 2%-4% of a first foaming agent, 1%-2% of a second foaming agent, 1%-3% of inorganic fibers and the balance of water, wherein dosage of the first foaming agent is the double of that of the second foaming agent. Under the normal-temperature and normal-pressure conditions, the inorganic fibers are dispersed in deionized water for prehydration treatment for 8-12 h, then the first foaming agent and the second foaming agent are added and evenly stirred at 60-80 DEG C, the mixture is foamed at the rotating speed of 5,000-8,000 rpm for 3-5 min, and the foam drilling fluid is prepared. The foam drilling fluid has good foaming capacity, high high-temperature-resistant and anti-pollution capacity, good dynamic yield point, good yield point and plastic viscosity ratio, good suspension property, higher inhibitive ability and proper water loss, can maintain the higher rate of penetration and water and rock carrying capacity in the drilling process and effectively solves the complex problems of wellbore instability, tool sticking, reservoir pollution and the like.

A process for reducing wellbore instability includes inputting pre-drilling assessment information into an hydraulics analysis and wellbore stability application, inputting a well plan into the hydraulics and wellbore analysis application, inputting a parameter measured at the wellsite into the hydraulics and wellbore stability analysis application, inputting an observation made at the wellsite into the hydraulics and wellbore stability analysis application, integrating the pre-drilling assessment information, the measured parameter, and the observation into the wellbore strengthening analysis application, and adjusting a drilling fluid parameter in response to the integrated pre-drilling assessment information, the measured parameter, and the observation.

The invention discloses a drilling fluid, a preparation method and an application. The drilling fluid is prepared from the following components in parts by weight: 100 parts of water and 0.5-5 parts of a shale inhibitor, wherein the shale inhibitor is 1-aminoethyl-3-methylimidazolium salt with structural formula shown in the description, R is R is Br, NO3, PF6 or BF4. The drilling fluid contains the shale inhibitor capable of effectively inhibiting shale hydration dispersion, and can effectively prevent surface hydration of montmorillonite in shale when being used for drilling large sections of shale formations prone to wellbore instability, so that shale swelling pressure is reduced, and wellbore stability is maintained.

The invention relates to a strong inhibitive drilling fluid for drilling shale for shale gas development and solves the problem of wellbore instability, and hydration collapse of the shale stratum is inhibited. The technical scheme of the strong inhibitive drilling fluid is that the the drilling fluid is prepared from the compositions of, by mass unit, 900-1,000 g of tap water, 30-60 g of bentonite for drilling fluid, 2-4 g of Na2CO3, 0.3-1 g of strong inhibitive filtrate reducer JT900 for drilling fluid, 0.5-1 g of potassium strong inhibitor FK-1, 2-5 g of coating agent FK-421 for drilling fluid, 1-1.5 g of shale inhibitor NF-923, 1-2 g of positive ion viscosity reducer XH-1, 2-3 g of shale stabilizer DLSAS, 4-6 g of reservoir shielding agent QCX-1, 2-4 g of blocking agent DE-1 and 0.5-1 g of lubricant RT-881 for drilling fluid; finally, the alkali liquor with the mass percentage concentration of 40% is prepared by adding water to NaOH, the system PH is adjusted to be 8.5, the drilling fluid weighting agent baryte is used for weighting the the system density to be 1.8-2.0 g/cm<3>, and the drilling liquid is prepared. The drilling fluid system has small environment pollution, and the drilling liquid has excellent rheological property and high sealing capacity and is used for drilling the shale.

The invention discloses oil-based shaft stabilizing fluid for gas-liquid conversion and a preparation method thereof and relates to working solution for gas-liquid conversion in the petroleum and gas drilling process. The preparation method comprises the following steps of: uniformly dissolving 3 to 5 parts of tackifier into 50 to 75 parts of mineral oil at a temperature of 20 DEG C to 60 DEG C and sufficiently stirring for 1 to 2 hours; then adding 5 to 20 parts of surfactant and sufficiently stirring for 1 to 2 hours; and adding 5 to 20 parts of formation sealant and 3 to 20 parts of temporary plugging additive and sufficiently stirring for 2 to 3 hours to form fluid with stable performance, i.e. the oil-based shaft stabilizing fluid for gas-liquid conversion. According to the invention, a mode of combining chemical and physical means is adopted; and while a well wall is prevented from being collapsed, the loading capacity of an open formation is improved, the possibility of wellbore instability and lost circulation in the gas-liquid conversion process is reduced, the unproductive time is shortened, the drilling effectiveness is improved and the drilling cost is saved.

The invention relates to a protective device for a directional penetrating pipeline. The problems that the penetrating pipeline is crushed, damaged and locally deformed are solved. According to the technical scheme, a protective pipeline is arranged outside the penetrating pipeline in a sleeved mode, the length of the protective pipeline is equal to that of the penetrating pipeline needing to be protected, a sealing ring and a slip are arranged at the two ends of a protective pipeline, fluid is filled into a circle between the protective pipeline and the penetrating pipeline, and the pressure of the fluid is smaller than that of internal media in the penetrating pipeline. The slip and the sealing ring seal the annular fluid and tightly hold the penetrating pipeline. The penetrating pipeline is effectively protected, the situation that pipeline is crushed, broken, injured by a crashing object and locally deformed due to wellbore instability is avoided, the penetrating pipeline is prevented from being repaired or replaced or penetrating a new pipeline again, and the protective device is especially suitable for protecting pipelines penetrating through rivers, gravel layers, soft and hard connecting strata, faults and easily-collapsing strata and the like.

A treatment apparatus and method for wellbore instability is described including a caliper with one or more radially extending arms which are capable of extending and retracting movement in a radial direction and a fluid supply facility to deliver treatment fluid from the ends of the arms to the wellbore wall, with a sensing and valve mechanism such that in use fluid is being delivered from the end of any extended arm to a breakout region of the wellbore where there is instability.

The invention relates to a continuous circulation drilling system and method. The continuous circulation drilling system is formed by connecting of a rotating blowout preventer, a full-sealing blowout preventer, a semi-sealing blowout preventer, a four-way joint, an anti-rotation hanger, a circulation outlet, a high-pressure side circulation opening, a throttling flow path and the like. According to the system, in drilling of a complex stratum, drilling liquid circulation is still kept during the period of making a connection, accordingly stable equivalent circulating density and unintermittent rock debris discharging are achieved in the whole drilling period, downhole pressure is kept balance, the borehole condition is improved overall, the situations that downhole accidents such as pump suffocation, jamming of a drilling tool and overflow occur due to sand setting, wellbore instability and unbalance of the downhole pressure caused by making the connection in common drilling are avoided, and the success rate and safety of complex stratum drilling operation are improved.