Deliverability Evaluation And Development Technology Policy Research Of Shale Gas Reservoir In Block W

The shale gas reservoir in block W is in the early stage of development,which has an abundant geological reserves of 1175.27×108m3.In 2015,the exploration well(W1)of the block obtained a test output of 17.5×104m3/d,which revealed a good exploration and development potential.However,the understanding of single well productivity and reasonable development technology policy of the reservoir is insufficient,which needs in-depth research.This paper studied the productivity and development technology policy of the target gas reservoir through gas reservoir engineering theory and numerical simulation method.The main research results are as follows:(1)The target layer of Longmaxi formation is divided into 9 small layers.From top to bottom,the content of clay minerals decreases gradually,and the content of brittle minerals keeps about 40%,and the reservoir physical property becomes better gradually.The ④⑤⑥⑦ layer of 1 sub section of Longmaxi formation is the best reservoir,which can be divided into a set of layer series of development.Its main properties are as follows:the total thickness is 49m;the average porosity is 4.15%;the average permeability is 2.41 ×10-3mD;the total gas content was 4.24m3/t in average;the average measured Langmuir Volume is 5.03 m3/t,and the average measured Langmuir Pressure is 2.77 MPa.(2)The paper evaluated the productivity of well W1 according to the binomial deliverability equation.Its absolute open flow(AOF)is 23.87×104m3/d.Compared with the productivity of shale gas wells in adjacent area,it is concluded that well Wl belongs to the middle output well.(3)The paper established a steady productivity model of fractured horizontal well,which considers stress sensitive and non Darcy flow.The study on the main control factors of steady state capacity shows that:with the increase of reservoir permeability or reservoir thickness,well’s AOF increases linearly,and it is more sensitive to permeability;The greater the stress sensitivity coefficient,the lower the AOF;with the increase of fracturing number or crack half length,the AOF increases,but the growth rate decreases gradually,especially when the fracturing number is more than 20 and crack half length exceeds 200 m;with the increase of angle between the artifical fracture and horizontal section,the AOF increases and reaches the maximum at orthogonality;three fracture distribution modes are sorted as follows in the descending order of AOF:fractures densely distribution at both ends of the horizontal section>fracture uniform distribution>fracture densely distribution at the middle of horizontal section.(4)The paper established the numerial model of shale gas reservoir by Eclipse on the basis of the geological model of the block.Through the gas indication curve method,the critical carrying liquid production method,the nodal analysis method and the numerical simulation method,the production mode of constant production rate is recommended,and the reasonable production rate is 5×104m3/d.It is predicted that the well can produce steadily for 11 months,and the cumulative gas production is 6516×104m3 in 15 years.(5)The parameters optimization of the fractured horizontal well is studied by numerical simulation method,and the reasonable parameters are as follows:The horizontal section of horzontial well is distributed in the direction of north and south;the length of the horizontal section is 1500 m,the number of hydraulic fracturing section is 20,and half length of artifical fracture is 150 m.(6)The cluster well is adopted in the block,and one well group contains 6 wells.The reasonable distance of well is 500 m,and the reasonable distance of well row is 3900 m.The control area of the well group is 4.91 km2,and the control reserves is 35.25×108m3.The predicted cumulative gas production in 15 years of well group is 3.917×108m3,and the recovery is 11.2%.The development effect of CO2 huff-and-puff and continuous injection of CO2 is studied by simualtion,and the exhaustion development mode is still recommended.The study of this paper can provide some technical guidance for the overall exploitation of shale gas reservoirs in block W.