CC BY
11TECHNICAL SCIENCES
FEATURES OF THE TECHNOLOGY OF DRILLING AN INCLINED DIRECTIONAL
EXPLORATION WELL
Deryaev A.
Candidate of Technical Sciences, Senior Researcher, Scientific Research Institute of Natural Gas of the State Concern „ Turkmengas", Ashgabat, Turkmenistan https://doi.org/10.5281/zenodo.6992252
Abstract
The article discusses the choice of the well design and drilling fluid, and also presents the result obtained during the development of an inclined-directional exploration well using the method of dual completion (DC) by two elevators with pumping and compressor pipes. When drilling this exploration well, the design has been changed in contrast to the previously used conventional design at the Northern Goturdepe field. This work can be used to conduct drilling operations in deep wells in fields with complex mining and geological conditions and abnormally high reservoir pressure in order to successfully conduct drilling operations.
Keywords: mine direction, wellhead erosion, shoe, packer, hydrocarbon-based solution, slit filter, emulsion.
On the basis of the combined pressure graph and calculation of the wellbore trajectory, the following design was selected at well №147 North Goturdepe.
- the shaft direction 0 720mm descends to a depth of 10m, is fixed with butobeton.
- the elongated direction of 0 630mm descends to a depth of 30m, in order to overlap unstable, sandy-clay deposits and prevent erosion of the wellhead when drilling under the conductor. The height of the cement lifting is up to the wellhead.
The conductor 0426mm descends to a depth of 596 m, provides overlap of the upper part of unstable sandy-clay quaternary deposits, isolation of the borehole from hydrostatically connected waters with the surface and installation of anti-blowout equipment.
The 0324mm technical column descends to a depth of 2701 meters to cover the swelling and collapse of "black clays", is equipped with anti-blowout equipment and provides effective well management in case of possible manifestations. The height of the cement rise behind the column is up to the wellhead.
The descent of a technical column with a diameter of 0244.5 mm is carried out to a depth of 4206 meters (along the hole), (vertically) 4148 meters, into the roofing part of the productive horizon IX d + e with an adjustment according to logging data. The shoe of the technical column is installed in clay deposits [1].
The casing 0244.5 mm column was selected according to calculations for the perception of all loads arising during drilling and operation of wells. The height of the cement rise behind the column is up to the wellhead.
The descent of the operational slot shank - filter 0139.7mm, is carried out to a depth of 4555 meters along the hole, 4221 meters vertically, with the installation of a suspension device for 50-100 meters inside the casing 0244.5 mm. The descent of the slit shank -filter 0139.7mm combination with casing pipes is carried out in order to attach the filter to the wall of the
well and isolate productive layers from others. The fastening is made by special expansion packers installed as part of the descent slot shank - filter 0139.7 mm.
According to well-known schemes, wells with directional finishing filter without cementing in productive zones has the following advantages:
- simple mounting technology;
- the bottom-hole zone of the productive formation is not polluted with cement;
- ensures the safety of the hole;
- it is possible to carry out work on cleaning the
hole.
At well №147 North Goturdepe from a depth of 600 meters to 3800 meters, drilling was carried out on the drilling fluid "ALKAR-3M" developed by the institute "Nebitgazylmytaslama" The State Concern "Turk-menneft". To increase the stability of the well walls and prevent complications, the formulation of the inhibited system of alumocalcium solution "ALKAR-3M" was developed and introduced into production at the Institute of "Nebitgazylmytaslama". The system is stabilized with lignosulfonates. As an inhibitor containing simultaneously anions (chromate-aluminates, ferrates) and cations (calcium, potassium, magnesium), alkaline and acid hydrolysates of Portland cement are accepted. As a hydrophobic surface active substance (hereinafter surfactant), classes of polyoxyalkylenes in selective solvents have been proposed that perform the functions of a defoamer and a lubricating additive [2].
The industrial surfactant product provides an inhibitor of paraffin deposits in HT-48 oil.
The ALKAR-3M system, due to its inhibitory properties, suppresses the lyophilicity of clays;
1. Allows you to pass colloidal clays without an accident (taking dangerous packs of black clays of the Absheron tier),
2. Leads to significant savings in chemical reagents by reducing the number of treatments, since the solution retains optimal viscosity and structural and mechanical properties for a long time during drilling.
The difference between the inhibiting solutions of the system and the ALKAR system is that they have an increased clay capacity, but ALKAR-3M still has the fastening properties of the filtration crust, due to which an increase in the stability of the borehole zone of the well is achieved. Therefore, the solutions transferred to the inhibited ALKAR-3M system can withstand large values of water yield by 1.5-2.0 times in comparison with the required values laid down in the geological and technical order and at the same time are able to maintain the stability of the wellbore for a long time.
One of the properties of ALKAR-3M is a set of structural strength over time. Therefore, after long stops (for the period of geophysical research and others) restoration of the circulation of the solution is carried out intermittently after the drilling tool is lowered into the cased part of the borehole (casing shoe). This causes the sedimentation stability of the solution for a long time and reduces the likelihood of the drill string being seized due to the retention of barite particles and drilled rock.
The productive deposits of the deposits of Southwestern Turkmenistan are characterized by a complex and ambiguous composition of rocks, waters and drilling fluid, and oil. Each of the components, interacting with the filtrate of the drilling fluid, determines the deterioration of reservoir properties and a decrease in the flow rates of hydrocarbon fluids.
This deterioration is mainly due to two processes, the swelling of clays and the formation of emulsions. The weakening of these processes is carried out through the use of drilling fluids, the filtrates of which have a combination of inhibitory and surface-active properties. Depending on the specific features, in particular, the degree of reservoir blockage, solutions containing mineral inhibitors and surfactants HT-48, in comparison with other types of clay drilling fluids have better c (minimal filtration of water into the reservoir) properties, both when drilling a well and when opening productive deposits.
For the opening of productive horizons with preservation of natural permeability, as well as for drilling in particularly unstable clay saline deposits, the use
Table 1
Types and parameters of drilling fluids for drilling production well № 147 of the Northern Goturdepe field with
of oil-based solutions. In such solutions, the dispersion medium is represented by diesel fuel, and the dispersed phase is finely ground oxidized bitumen.
At well №147 Northern Goturdepe, all productive horizons were opened on hydrocarbon drilling fluid. From a depth of 3800 meters to a design depth of 4400 meters.
The construction and opening of the productive part of the well №147 Northern Goturdepe was carried out on a solution of a hydrocarbon base. When drilling the hole of 295.3 mm, a substitution was made for a solution of a hydrocarbon base of the "Versadril" type, from a depth of 3800m. Further, the hole of 295.3 mm from a depth of 3800 meters to a depth of 4206 meters along the hole was drilled obliquely on a solution of a hydrocarbon base of the "Versadril" type. Drilling fluid "Versadril" is a hydrocarbon-based system that uses diesel as a basis to prevent the swelling of clays. The system "Versadril is one of the most ideal systems for drilling active clays, where the stability of the hole is the main issue, in addition, this system operates at high temperatures up to 180-190 degrees and has more improved rheological properties of the solution and inhibition [3]. To drill this interval, the equipment of the company "Schlumberger" was used to set the angle and exit in the direction, which requires special control of the rheological parameters of the drilling fluid. The choice of a hydrocarbon system was based on the composition of this system, which is a direct emulsion, where the aqueous phase is a dispersed medium, which excludes the chemical reaction of the solution with rocks in the well. Calcium carbonate (Safe Carb) was added to this solution in order to prevent the penetration of filtrate and minor absorption. The addition of calcium carbonate makes it possible to stop the penetration of filtrate into microcracks and prevent instability of the borehole. The type, parameters and components of the used hydrocarbon drilling fluid for productive horizons for the II technical and operational column at well №147 Northern Goturdepe are given in Tables 1,2.
Name (type) of the solution Interval, m Drilling mud parameters
From (top) Up to (bottom) Density, g/cm3 Conditional viscosity, sec. Water output, cm3/30min Crust, mm Static shear stress, kgfcm in, min
1 10
oil emulsion humate-lignosulfonate 0 600 1,22 40-50 10-12 2-3 10-20 20-30
ALKAR-3 600 1900 1,26 25-35 8-10 1,5-2 5-10 5-15
ALKAR-3M 1900 2700 1,45 30-40 6-8 1-1,5 5-10 5-15
ALKAR-3M 2700 3730 3800 1,35 1,35 30-40 30-40 4-6 3-4 0,5-1 0,5 5-10 510 5-15 5-15
A hydrocaibon-based solution "Versadril" 3800 4400 1,40 45-60 2-3 0,5 10-15 10-20
Drilling of 215.9 mm of the hole from a depth of 4206 meters to a depth of 4555 meters along the hole, was drilled obliquely at a zenith angle of 45 degrees and an azimuth of 264 degrees, with a displacement of 298
meters on a solution of a hydrocarbon base of the "Versadril" type. The system "Versadril" has a high emulsion stability and has a diesel/water ratio at 70/30 with electrical stability, being maintained at 800-1500 Volts
to create an emulsion and maintain the necessary parameters of the solution of this interval.
Considering that this interval is productive collectors, the water output readings were kept within 3ml/30 minutes. This water output minimized the likelihood of damage to the collector and sticking of the drilling tool [4].
So, in case of technological necessity of using drilling fluids with a solid phase, the mechanical speed
Table 2
Type, parameters and components of the used hydrocarbon drilling mud for drilling production well №147 of the Northern Goturdepe field with an obliquely directional bore
of penetration and penetration into the bit is sharply reduced due to the deterioration of the working conditions of the drill bit. Eliminate or significantly reduce the influence of the solid phase in the drilling fluid. In order not to damage productive reservoirs, the solid phase content at the well was reduced to a minimum of less than 5%.
Name (type) of the solution Interval, m Drilling mud parameters
From (top) Up to (bottom) Phase composition, % vol. pH Mineralization, mg/l Plastic viscosity, sDr Dynamic shear stress, mg/cm2 Ca+2 mg/l
Voil Vsol yf
oil emulsion humate-lignosulfonate 0 600 8,62 11,87 79,51 8,5-9 13-15 18 33 300-400
AHKAP-3 600 1900 10,62 13,92 75,46 11-12 15-17 5-8 10-20 900-1500
ALKAR-3M 1900 2700 10,62 20,71 68,67 11-12 15-17 10-12 10-20 900-1500
ALKAR-3M 2700 3730 3800 13,21 13,21 17,24 17,24 69,55 69,55 11-12 11-12 15-17 15-17 10-12 10-12 10-20 1020 900-1500
A hydrocarbon-based solution "Versadril" 3800 4400 65,09 18,64 16,27 9-9,5 15-17 5-10 8-12 500-600
During the development of the well by the DC method, a large inflow of oil was obtained, the results of the study are shown in Table 3.
Table 3
Data on perforations and indications of studies during the development of well №147 of the Northern Goturdepe
field
Object designation, type of perforator, number of holes Distance of the test object, (m) Age, artificial depth, (m) Development results
I PKO -102 504 4008-4030 4040-4050 Pack IX I-lift tubing received oil inflow Dconnect pipe = 10mm, Pwork=108 atm. Qf=321,3 m3/day. Qoil=234,33 m3/day.
Special filter 4150-4193 4238-4248 Lower red color K-1 II -lift tubing received oil inflow Dconnect. pipe =30mm, Pwork =24 atm. Qf=557,1 m3/day. Qoil=426,1 m3/day
The figure shows the design of well №147 on the Northern Goturdepe square with a two-lift tubing with downhole equipment for DC.
Figure. Design of well №147 with a two-lift tubing with downhole equipment for the DC at the North Goturdepe
field
References:
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